On what the real problem is, and if you can compensate for it.
If your problem with math is that you can't handle generic problem solving, and instead try to memorize solutions then your probably screwed in programming.
On the other hand, you don't understand math because no one told you (or you haven't tried to understand) how it works, or what its used for, then that may just be a problem with your education and probably won't impact your programming abilities.
Or maybe your just a little slow learning it, nothing is really wrong, you just need a little more time. In that case it probably won't affect your programing abilities unless your really slow learning to program....
I suggest that if you think about it, or talk to a bunch of people about what exactly you don't understand about math, then you will have a clearer picture of whether programming is to closely related to math too make it a career.
PS: I myself had varied math success while in school. Some subjects like calculus I did really well in. Some subjects not so well. To this day, I wish I had taken more math in school (I stopped after first semester diffeq). It sucks to have to bang my head against some math concept for weeks before I get it enough to understand why something works enough to implement it well. Last year, I spent a few weeks studying galois theory and kicking myself for not taking abstract algebra when I was in school.
That said, a lot of "advanced" math shows up in the strangest of places. Sometimes without sufficient background you won't even be able to identify it. So, your stuck trying to solve a problem the "hard" way.
So, while a lot of people are saying you don't need it for specific areas in computing, if your programming for long, you will run into things more advanced than linear algebra, even if all your doing is "business programming".
While those things she list are important, it sounds like this woman actually worked in an environment where the low level architecture wasn't controlled or defined by someone with any experience with long term maintenance.
There are a lot of really good coders, but the skills required to properly define high level interfaces between subsystems is _NOT_ something all of them posses, even though the vast majority either think they do, or fail to understand the importance of defining project API's for isolation.
This isn't to say that people with the term "architect" in their titles get it any better. In many cases they tend to get it wrong because they are too decoupled from the actual coding portions.
Its also something that is nearly impossible to bolt on after the fact. The last thing your project manager wants to hear, is that 3/4 of the project needs to be rewritten (or refactored to the point its not recognizable) because of some stupid problem with component isolation.
So, how to you identify bad architecture?
If your team can't isolate and troubleshoot the vast majority of bugs quickly (less than a hour).
If the common answer to features, is that some large portion of the system needs to be rewritten or refactored.
If the system is brittle, and errors aren't contained to smaller subsystems.
If requirements changes tend to touch a lot of different system components.
The list goes on, but I firmly believe that bad architecture is the problem in a lot of cases where people claim crappy code, or failures because the product is buggy or is not agile enough to respond to market needs.
Did it actually come bundled with the Laser 128? If so, that's hilarious!
At the time, I didn't find it strange, but later the idea that the first and only piece of software you needed for an Apple ][ was a disk clone program seemed amusing. The only thing missing was the stack of blank floppies.
We did some serious damage with Locksmith and Essential Data Duplicator back in the day.. till I read Pirate's Harbor and The Computist... then it got fun.
I was always a Copy II+ guy, never got into the other utilities. Probably because I knew how to create new nibble copy profiles for copy II+ and it was usually easier to read the track, look at it and create a new profile than find a preexisting profile some else created. Mostly because, I didn't have a modem for the first few years, eventually saving up my pennies for a 2400 bps. I also cracked a couple games myself. Mostly using a little undocumented "bug" I discovered on the laser that allowed one to press ctrl-enter-reset and drop to the monitor. No need for the fancy debug boards other people put in their apple ][s. I'm sure other people knew about it too, I just never found anyone else talking about it.
Hehehe telemate was way cool. I remember writing a little script for some apocalyptic BBS door which hit the spacebar at the correct time during combat to assure I got a perfect hit all the time. Can't remember the door name though, what I do remember is that the game "cheated" by adjusting the delay depending on how deep into the dungeon you were. Then it started adding a randomization function.
So, I added a bunch of code to compensate for these variations and it allowed me to survive in locations that a normal human simply would be unable to win at combat.
Anyway, one day I'm walking around on the hardest level, and I ran across another player! I just remember my shock when I realized, those other f**kers must be cheating!
A couple years ago I recovered a bunch of my early code and moved it to a apple emulator. While doing that I loaded some of those "huge twisty" programs up in my editor, which has ~250 vertical lines. Its pretty amazing, because the ones with goto's aren't that bad when you can see most of the program screen at once. The ones that are the problem are the ones that are 30% peeks and calls because I no longer remember what all those addresses do.
I don't remember that contest being much fun because it didn't take long for most of the code to be something like "call -xxx: rem a,b,c,d,e"
Where the a,b,c etc was tokenized basic and the call was some rom location that skipped the basic interpreter past the rem, the other option was jumping to assembly encoded in the rem.
Basically, you needed a disassembler or a applesoft token look-up table to determine what was going on.
I convinced my mother to buy a Laser 128, which for those not familiar was a apple ][ clone priced more like a C64.
Anyway, got it home and the only software it came with was a copy of Copy II+, a disk cloning product. It did come with a nice reference manual though.
Money being tight and all, my supply of games/etc was very limited. So instead I started reading the manual, and trying to understand all basic keywords and technical jargon. By the time I was in HS, I was pretty proficient with that machine having learned enough BASIC and assembly to write my own editor/assembler, and a number of 1/2 hearted attempts at my own games.
Your sneering tone about "appearing green" ignores the genuine increase in efficiency from an electric drive. No doubt you'll bleat about coal powered cars, ignoring the increasing role of cleaner natural gas in USA's electricity generating mix, and that many buyers will install solar PV to reduce their carbon footprint further.
You say that like natural gas is good....
Even so, unless people buying those cars have meters in their garage that tell them when the wind farm is blowing, its likely its base load being supplied by the trusty coal or nuke plant. Currently, In most places natural gas is being used as peak load, or to supplement renewable.
So hypothetically, an electric car buyer _could_ install solar panels but installing sufficient solar capacity to charge their cars is going to cost as much as the vehicle and is supplied at inconvenient times for charging an automobile. Furthermore, if electric cars became the normal within the next 5 years, where do you think all that electricity is going to come from? Right now its probably going to be natural gas, which is cleaner than coal but has a big fat CO2 footprint (and then there is the claim that leaking methane from production is significant) too, especially when transmission/charging/etc losses are computed. So, its quite possible that simply converting to a natural gas vehicle gives you more of an advantage. Look here http://www.eia.gov/oiaf/1605/coefficients.html#tbl2 to see that natural gas is only about 33% better than than petrol for Btu per unit CO2.
Really, if you want a green battery car, the electric mix should be significantly tilted towards nukes. But many of the same people advocating electric cars are out their advocating wind power. Which is a good idea, but no where near scalable in the short term to cover current generation needs much less the energy needs if everyone switched their cars to electric overnight. When I hear "green" people taking about renewables I just think, they are advocating more natural gas and a significant increase in energy costs. And that is why renewable has had a slow uptake. Its not a simple as building windmills and solar plants everywhere and reaping the rewards. If it were then we would have built them 30 years ago. No, for every MW of wind energy someone is buying a MW of small natural gas generators that can be spun up fast to compensate for the fact that the wind cannot be controlled.
So, the green heads are as much at fault for the climate change problems as anyone. Because, when faced with a choice of solutions they tell people to pick either massive energy price increases or a quality of living decline. Its not really any surprise that people just kick the problem down the road, and they will continue too until the green heads wake up and realize that we have the technology to provide truly clean energy at prices that would make buying an electric car pay for itself when compared with petrol. Instead they run around and fear monger about things based on anecdotal evidence and lack of knowledge instead of actually looking at the statistics and science.
So, yes calling the tesla a coal burner, may be stretching a little, but it is not far off. Enjoy the car for what it is, but don't pretend its somehow more green than buying a toyota yaris, ford focus or any of the many other efficient gas automobiles.
Or its simply the fact that dynamic power is related to the switching speed via the square of the voltage * frequency. So, increasing the clock and voltage causes the power to go up significantly for a given number of transistors.
So, its an evil tradeoff, add more transistors increase leakage, or bump the clock rate and increase the dynamic power.
AMD has chosen the faster clockrate, for a few percent decrease in efficiency, while Intel has chosen the save power option for a few percent decrease in performace. It makes sense as intel is top performance dog right now. Being top power dog is now their focus. If AMD starts getting close they will release another i7 EE with more memory channels and clocked another Ghz faster.
In both cases, I'm sure they could design a CPU with a TDP of 300W and give themselves a clockrate bump to match the 5.5Ghz zSeries IBM sells. Of course then they would need a huge blower like IBM uses. I'm sure that if either of them thought they could get away with selling a few $500k CPUs to fit in a $20 million machine they would do it.
I think your fix would be more reasonable if you cited examples of when liberal politicians ignored science to match their agendas.
While I generally agree that the R's pretty much ignore science, gun control is an example of where the D's ignore it.
Specifically US related data, while there isn't much, what there is, points at gun control being useless in the US for controlling gun related homicides. Areas with the highest homicide rates also tend to be the ones with the strictest gun control (see Chicago and DC, etc) laws.
I was pretty shocked too, I didn't know you could get in anywhere with under 700. Christ, those have to be athletes because a 700 on the SAT is like 6th grade education.
It doesn't say what percentage of the students getting aid are under 700. Even so, how does one function in college if you don't have a grasp of algebra or any kind of reading comprehension?
The "slow interconnect" you're talking about to main memory, PCI Express v3.0 has an effective bandwidth of 32GB/s which actually exceeds the best main memory bandwidth you'd get out of an Ivy Bridge CPU with very fast memory, so no, that's not a bottleneck for bandwidth, though yes, there is some latency there.
Its both, for my application, the GPU is roughly 3x-5x as fast as a high end CPU. This is fairly common on a lot of GPGPU workloads. The GPU provides a decent but not huge performance advantage.
But, we don't use the GPU! Why not? Because copying the data over the PCIe link, waiting for the GPU to complete the task, and then copying the data back over the PCI bus yields a net performance loss over just doing it on the CPU.
In theory, a GPU sharing the memory subsystem with the CPU avoids this copy latency. Nor does it preclude still having a parallel memory subsystem dedicated for local accesses on the GPU. That is the "nice" thing about opencl/CUDA the programmer can control the memory subsystems at a very fine level.
Whether or not AMD's solution helps our application remains to be seen. Even if it doesn't its possible it helps some portion of the GPGPU community.
BTW: In our situation its a server system so it has more memory bandwidth than your average desktop. On the other hand, i've never seen a GPU pull more than small percentage of the memory bandwidth over the PCIe links doing copies. Nvidia ships a raw copy benchmark with the CUDA SDK, try it on your machines the results (theoretical vs reality) might surprise you.
Without sounding like too much of a jerk, I have hundreds of commits in the linux-2.6 fs/* tree. This is what I do for a living.
Well, then your part of the problem. Your idea that you have to be correct or fast is sadly sort of wrong. Its possible to be correct without completely destroying performance. I have a few commits in the kernel as well mostly to fix completely broken behavior (my day job in the past was working on an enterprise unix). So, I do understand filesystems too. Lately, my job has been to replace all that garbage, from the scsi midlayer up, so that a small industry specific "application" can both make guarantees about the data being written to disk while still maintaining many GB/sec of IO. The result, actually makes the whole stack look really bad.
So, I'm sure your aware that on linux, if you use proper posix semantics (fsync() and friends) the performance is abysmal compared to the alternatives. This is mostly because of the "broken" fencing behavior (which has recently gotten better but still is far from perfect) in the block layer. Our changes depend on 8-10 year old features available in SCSI to make the guarantees that aren't available everywhere. But it penalizes devices which don't support modern tagging, ordering and fencing semantics rather than ones that do.
Generally in linux, application developers are stuck either dealing with orders of magnitude performance loss, or they have to play games in an attempt to second guess the filesystem. Neither is a good compromise and its sort of shameful.
Maybe its time to admit linux needs a filesystem that doesn't force people to choose either abysmal performance, or no guarantees about integrity.
99% of software doesn't need to call fsync() on a sanely designed filesystem.
Really? please, show me the part of POSIX which says the data you wrote has now been flushed to the medium and you can respond with 100% certainty, to the user, or API making a request that if power fails this transaction will be safe.
Well, if linux is a toy (your basic argument) then why are all the subsystem maintainers paid by large companies a salary same as the developers at Microsoft, or any other OS company?
My point doesn't preclude people showing up and writing the next great filesystem. Its simply a question of why everyone thinks its a good idea for a guy PAID to maintain a filesystem to drop it and go write another one. If you worked for _BIG_ company and were paid to maintain their application, and you decided one day that maintaining their application was a PITA cause it was old crufty and not sexy anymore and instead refused to fix problems in it, rather spending the next 4 years writing a replacement (complete with another set of bugs) how long do you think your job would last?
Of course, this stuff happens in a lot of software projects, new developer shows up, and writes buggy new system cause they think they are smarter than the last guy. It frankly speaks of immaturity and an "artist" mentality rather than an engineering process. Sure, software isn't all engineering but linux is an OS, its a fundamental part of a computing platform and one that is expected to provide some basic level of service to applications (you know the things actually doing the work). When it fails at that, because its a patchwork of art, then you have to question why.
Ext3 is still chugging along and doing what you want. A filesystem that sacrifices everything for stability.
EXT3, is actually fairly good, and the performance isn't bad _EXCEPT_ for one issue. fsync(), which causes a massive IO barrier against all the other operations in the filesystem. fsync() should only be assuring the named file is consistent, and yet it basically stalls the entire FS to assure that one file. Its a problem with lack of proper IO tagging and actually is a fundamental problem with the block layer in linux. A recent LSML posting about SYNCHRONIZE CACHE hints at the problem too (complete device flush when only a small portion of the IO needs to be flushed).
No, that's FUD and/or misunderstanding on your part.
"data=ordered" is ext3/4's name for "don't expose stale data on a crash," something which XFS has never done,
Actually, I think your the one that doesn't understand how a journaling file system works. The problem with XFS has been that it only journals meta data, and the data portions associated with the metadata are not synchronized with the metadata updates (delayed allocation an all that). This means the metadata portions (filename, sizes, etc) will be correct based on the last journal update flushed to media, but the data referenced by that meta-data may not be.
A filesystem that is either ordering its meta data/data updates against a disk with proper barriers, or journing the data alongside the meta data doesn't have this problem. The filesystem _AND_ its data remain in a consistent state.
So, until your understand this basic idea, don't go claiming you know _ANYTHING_ about filesystems.
That will probably get 95% done before the next cool kid on the block takes over.
Filesystems on linux never seem to be 100% done. By that I mean, they are bulletproof and reasonably fast.
Just think, if instead of having dozens of primary fileystems (ext[2,3,4], reiserfs, ocfs, ocfs2, xfs, jfs. gfs2, zfs) over the last 15 years, someone had actually spent the time and designed/researched a general purpose filesystem, implemented and slogged through all the issues on one of them. Linux might have a good filesystem. The ext2/3 combination appeared to be on that path, but instead of fixing the fsync problems, and a couple other issues, it was basically abandoned in favor of ext4 which while maintaining the ability to mount ext3, and is named the same could have just been called "we took some bad ideas from XFS for performance reasons and now we have the same data integrity problems".
Your happy with XFS because your machine has never lost power or crashed. If either of those things happened with the older versions of XFS it was nearly a 100% guarantee you would lose data. Now i'm told its more reliable.
So, if you told me you have been running it for the last year and it was reliable I would have given you more credit than claiming you have been running it for a decade and its been reliable. Because, its had some pretty serious issues that if you didn't hit them means your not a good test case.
I'm still skeptical, because AKAIK, XFS still doesn't have an order data mode.
I don't remember MS ever giving word away except at events, as they still do with much of their software. If anything it was darn expensive.
The reason Word won, has more to do with WordPerfect than Word. Wordperfect was THE DOS editor everyone used. But it was a real PITA, without the keyboard overlays it was impossible to learn to use. Oh, and formatting your output was a nightmare of control codes sprinkled all over the text which visually bore no resemblance to the output. To enjoy a modern version of the experience you could try TeX in emacs on a 80x25 terminal...
So, along comes word for windows, and its WYSIWYG (for the most part), and pretty much overnight everyone was like wow that rocks, except for a few die hard wordperfect lovers. Wordperfect responded to word for windows by writing the ugliest VGA application possible (version 6 BTW) which came out a good year or two after word for windows 2. It bombed because it was both SLOW and BUGGY and the WYSIWYG function was barely better than the print preview function they had in 5.1 aka, it was more like WYSIWY Might Get.
Meanwhile, windows was getting better, you could buy accelerated 16 bit video cards,etc and with each video card release windows apps looked better and ran faster. Plus the printer functions in windows were maturing and you could get nice fonts/etc for windows and print them on basically any printer. Unlike wordperfect which had limited fonts and printer support.
Eventually word 6 was released, which was a very nice piece of software and pretty bug free. By the time wordperfect came out with an even buggier windows version it was game over for them. Word was stable, fast and quite usable on windows.
The only real competitor at the time was Ami pro which didn't waste any time bringing a windows app to market.
though I'm trying to figure out how they didn't manage that back when it was 6% only a decade ago.
I don't know what state you live in, but if its like the one I live in the answer is easy and its three fold.
First the population of the state is expanding fairly rapidly, but the laws on new development don't require the developers to pay for the privilege of adding to city services (water/roads/electric). So, everyone moving into town is effectively subsidized by all the existing residents. Sure they have been paying for these services elsewhere, but they didn't bring them with them and they are left rusting/underutilized in places like Detroit.
Secondly, the state itself has been reducing business and franchise taxes as fast as possible. This in turn is reflected in the state paying a smaller percentage back to the communities for education/infrastructure/etc. The local communities then turn around and do the only thing they can, raise sales and property taxes and in many communities its insufficient to make up the shortfall.
Thirdly, the police forces have been expanding nationally at a frightening rate, and they are becoming significantly more expensive. 20 years ago police choppers, SWAT teams, armored vehicles, infrared cameras, etc were unheard of. Now every 3rd rate city in the country has a minor army. We don't even need the national guard anymore because the police force is like a second military. Combined with the fact that the police unions are the only unions in the country that haven't been destroyed by the 'R's means that its likely average salary for the officer handing out tickets is significantly above the salary of the general population. So the city budgets are overwhelmingly paid to the police departments. Librarians get laid off, and the police get a raise.
Only a bunch of ideologues or people complete ignorant of power generation would fail to count nukes as clean energy. When your "waste" after decades of use can be contained in a few shipping containers and used to generate more electricity then its cleaner than the manufacturing byproducts of equivilant "Green" energy sources. The ERI numbers for nukes are staying fairly constant, while even the numbers for coal/NG are going up.
At this point the planet would be better off if we irradiated 99% of it to Chernobyl levels. Simply because it would then be allowed to revert to a sustainable fairly natural state. The current state of affairs is going to be much worse.
Most of these systems are single purpose and fit in more as an embedded system than anything else.
So, what is the attack vector? Most of the XP exploits in recent memory are related to peoples browsing habits and pieces of the OS used by the browsers being susceptible.
So, the fact that people aren't surfing the web probably removes 99% of the threat, leaving the remaining possibilities of a worm on the internal network exploiting an open system service (network share etc) that could be blocked or disabled.
If an exploit is found in a direct system service like that I'm betting MS rolls out a security patch anyway. Probably, just to avoid the liability issues (same way you get recall notices on 20 year old cars if the problem is severe enough and considered a manufacturing defect).
Its only once the installed base drops below 5% or so would I guess that MS really stops supporting it for critical problems. Once that happens its not going to be a target for new exploits anyway.
I'm just wondering how long it takes before they stop doing activations. I have a copy of XP that has never been activated, I'm keeping around just to see what happens. I suspect they release a no authorization patch at some point but right now if they did it I'm sure XP installs would take off again.
For some reason I can't find the paper linked in that article. But accessing 64k devices is basically nothing, especially if they are a bunch of virtual mod3s and mod9's like just about every mainframe config I've seen. And really its less than 64k because your terminals, tapes, etc are also in that address space. Its like saying I have 4 Gigabytes of IO space and each adapter only takes 16 bytes of it. Useless BS information. Really, I was thinking about the address space issues on the mainframe last year, and came to exactly the opposite conclusion. Its a limitation, especially since the address space is shared between LPARs. AKA if you have 20 LPARs, with independent devices its actually only 4k devices per LPAR, which could be really limiting, especially if you can't run EAVs and the max capacity per volume is 54GB.
But the real problem is that even if you attached 256 devices on multiple 8Gbit ficon channels, the CEC to IO drawer interconnect is going to be the bottleneck. Thats assuming you can start enough ficon commands to keep each channel busy.
Here are real numbers from IBM on their ficon performance at 8Gbit (still current speed).
Go look at emulex's site. Their numbers are over an order of magnitude better and they offer a 16Gbit board too.
Anyway, did you ask EMC why the numbers were worse on your other platform? I'm betting you can "tweak" it up to speed too. Rarely is the machine the bottleneck when talking on a SAN. Its almost always the disk subsystem. Linux out of the box on nearly every platform needs "tweakage" Many of the fiber channel drivers on linux have very shallow queues and need to be significantly deeper for IOP benchmarks.
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On what the real problem is, and if you can compensate for it.
If your problem with math is that you can't handle generic problem solving, and instead try to memorize solutions then your probably screwed in programming.
On the other hand, you don't understand math because no one told you (or you haven't tried to understand) how it works, or what its used for, then that may just be a problem with your education and probably won't impact your programming abilities.
Or maybe your just a little slow learning it, nothing is really wrong, you just need a little more time. In that case it probably won't affect your programing abilities unless your really slow learning to program....
I suggest that if you think about it, or talk to a bunch of people about what exactly you don't understand about math, then you will have a clearer picture of whether programming is to closely related to math too make it a career.
PS: I myself had varied math success while in school. Some subjects like calculus I did really well in. Some subjects not so well. To this day, I wish I had taken more math in school (I stopped after first semester diffeq). It sucks to have to bang my head against some math concept for weeks before I get it enough to understand why something works enough to implement it well. Last year, I spent a few weeks studying galois theory and kicking myself for not taking abstract algebra when I was in school.
That said, a lot of "advanced" math shows up in the strangest of places. Sometimes without sufficient background you won't even be able to identify it. So, your stuck trying to solve a problem the "hard" way.
So, while a lot of people are saying you don't need it for specific areas in computing, if your programming for long, you will run into things more advanced than linear algebra, even if all your doing is "business programming".
While those things she list are important, it sounds like this woman actually worked in an environment where the low level architecture wasn't controlled or defined by someone with any experience with long term maintenance.
There are a lot of really good coders, but the skills required to properly define high level interfaces between subsystems is _NOT_ something all of them posses, even though the vast majority either think they do, or fail to understand the importance of defining project API's for isolation.
This isn't to say that people with the term "architect" in their titles get it any better. In many cases they tend to get it wrong because they are too decoupled from the actual coding portions.
Its also something that is nearly impossible to bolt on after the fact. The last thing your project manager wants to hear, is that 3/4 of the project needs to be rewritten (or refactored to the point its not recognizable) because of some stupid problem with component isolation.
So, how to you identify bad architecture?
If your team can't isolate and troubleshoot the vast majority of bugs quickly (less than a hour).
If the common answer to features, is that some large portion of the system needs to be rewritten or refactored.
If the system is brittle, and errors aren't contained to smaller subsystems.
If requirements changes tend to touch a lot of different system components.
The list goes on, but I firmly believe that bad architecture is the problem in a lot of cases where people claim crappy code, or failures because the product is buggy or is not agile enough to respond to market needs.
Did it actually come bundled with the Laser 128? If so, that's hilarious!
At the time, I didn't find it strange, but later the idea that the first and only piece of software you needed for an Apple ][ was a disk clone program seemed amusing. The only thing missing was the stack of blank floppies.
We did some serious damage with Locksmith and Essential Data Duplicator back in the day.. till I read Pirate's Harbor and The Computist... then it got fun.
I was always a Copy II+ guy, never got into the other utilities. Probably because I knew how to create new nibble copy profiles for copy II+ and it was usually easier to read the track, look at it and create a new profile than find a preexisting profile some else created. Mostly because, I didn't have a modem for the first few years, eventually saving up my pennies for a 2400 bps. I also cracked a couple games myself. Mostly using a little undocumented "bug" I discovered on the laser that allowed one to press ctrl-enter-reset and drop to the monitor. No need for the fancy debug boards other people put in their apple ][s. I'm sure other people knew about it too, I just never found anyone else talking about it.
Hehehe telemate was way cool. I remember writing a little script for some apocalyptic BBS door which hit the spacebar at the correct time during combat to assure I got a perfect hit all the time. Can't remember the door name though, what I do remember is that the game "cheated" by adjusting the delay depending on how deep into the dungeon you were. Then it started adding a randomization function.
So, I added a bunch of code to compensate for these variations and it allowed me to survive in locations that a normal human simply would be unable to win at combat.
Anyway, one day I'm walking around on the hardest level, and I ran across another player! I just remember my shock when I realized, those other f**kers must be cheating!
Funny thing about those programs...
A couple years ago I recovered a bunch of my early code and moved it to a apple emulator. While doing that I loaded some of those "huge twisty" programs up in my editor, which has ~250 vertical lines. Its pretty amazing, because the ones with goto's aren't that bad when you can see most of the program screen at once. The ones that are the problem are the ones that are 30% peeks and calls because I no longer remember what all those addresses do.
I don't remember that contest being much fun because it didn't take long for most of the code to be something like "call -xxx: rem a,b,c,d,e"
Where the a,b,c etc was tokenized basic and the call was some rom location that skipped the basic interpreter past the rem, the other option was jumping to assembly encoded in the rem.
Basically, you needed a disassembler or a applesoft token look-up table to determine what was going on.
I convinced my mother to buy a Laser 128, which for those not familiar was a apple ][ clone priced more like a C64.
Anyway, got it home and the only software it came with was a copy of Copy II+, a disk cloning product. It did come with a nice reference manual though.
Money being tight and all, my supply of games/etc was very limited. So instead I started reading the manual, and trying to understand all basic keywords and technical jargon. By the time I was in HS, I was pretty proficient with that machine having learned enough BASIC and assembly to write my own editor/assembler, and a number of 1/2 hearted attempts at my own games.
Your sneering tone about "appearing green" ignores the genuine increase in efficiency from an electric drive. No doubt you'll bleat about coal powered cars, ignoring the increasing role of cleaner natural gas in USA's electricity generating mix, and that many buyers will install solar PV to reduce their carbon footprint further.
You say that like natural gas is good....
Even so, unless people buying those cars have meters in their garage that tell them when the wind farm is blowing, its likely its base load being supplied by the trusty coal or nuke plant. Currently, In most places natural gas is being used as peak load, or to supplement renewable.
So hypothetically, an electric car buyer _could_ install solar panels but installing sufficient solar capacity to charge their cars is going to cost as much as the vehicle and is supplied at inconvenient times for charging an automobile. Furthermore, if electric cars became the normal within the next 5 years, where do you think all that electricity is going to come from? Right now its probably going to be natural gas, which is cleaner than coal but has a big fat CO2 footprint (and then there is the claim that leaking methane from production is significant) too, especially when transmission/charging/etc losses are computed. So, its quite possible that simply converting to a natural gas vehicle gives you more of an advantage. Look here http://www.eia.gov/oiaf/1605/coefficients.html#tbl2 to see that natural gas is only about 33% better than than petrol for Btu per unit CO2.
Really, if you want a green battery car, the electric mix should be significantly tilted towards nukes. But many of the same people advocating electric cars are out their advocating wind power. Which is a good idea, but no where near scalable in the short term to cover current generation needs much less the energy needs if everyone switched their cars to electric overnight. When I hear "green" people taking about renewables I just think, they are advocating more natural gas and a significant increase in energy costs. And that is why renewable has had a slow uptake. Its not a simple as building windmills and solar plants everywhere and reaping the rewards. If it were then we would have built them 30 years ago. No, for every MW of wind energy someone is buying a MW of small natural gas generators that can be spun up fast to compensate for the fact that the wind cannot be controlled.
So, the green heads are as much at fault for the climate change problems as anyone. Because, when faced with a choice of solutions they tell people to pick either massive energy price increases or a quality of living decline. Its not really any surprise that people just kick the problem down the road, and they will continue too until the green heads wake up and realize that we have the technology to provide truly clean energy at prices that would make buying an electric car pay for itself when compared with petrol. Instead they run around and fear monger about things based on anecdotal evidence and lack of knowledge instead of actually looking at the statistics and science.
So, yes calling the tesla a coal burner, may be stretching a little, but it is not far off. Enjoy the car for what it is, but don't pretend its somehow more green than buying a toyota yaris, ford focus or any of the many other efficient gas automobiles.
Or its simply the fact that dynamic power is related to the switching speed via the square of the voltage * frequency. So, increasing the clock and voltage causes the power to go up significantly for a given number of transistors.
So, its an evil tradeoff, add more transistors increase leakage, or bump the clock rate and increase the dynamic power.
AMD has chosen the faster clockrate, for a few percent decrease in efficiency, while Intel has chosen the save power option for a few percent decrease in performace. It makes sense as intel is top performance dog right now. Being top power dog is now their focus. If AMD starts getting close they will release another i7 EE with more memory channels and clocked another Ghz faster.
In both cases, I'm sure they could design a CPU with a TDP of 300W and give themselves a clockrate bump to match the 5.5Ghz zSeries IBM sells. Of course then they would need a huge blower like IBM uses. I'm sure that if either of them thought they could get away with selling a few $500k CPUs to fit in a $20 million machine they would do it.
I think your fix would be more reasonable if you cited examples of when liberal politicians ignored science to match their agendas.
While I generally agree that the R's pretty much ignore science, gun control is an example of where the D's ignore it.
Specifically US related data, while there isn't much, what there is, points at gun control being useless in the US for controlling gun related homicides. Areas with the highest homicide rates also tend to be the ones with the strictest gun control (see Chicago and DC, etc) laws.
as any selective college will be reading essays you wrote themselves.
Ha, I know someone who sells college admission essay help.... Basically, give them some money, your essay gets corrected/rewritten.
Its nice to have money..
I was pretty shocked too, I didn't know you could get in anywhere with under 700. Christ, those have to be athletes because a 700 on the SAT is like 6th grade education.
It doesn't say what percentage of the students getting aid are under 700. Even so, how does one function in college if you don't have a grasp of algebra or any kind of reading comprehension?
The "slow interconnect" you're talking about to main memory, PCI Express v3.0 has an effective bandwidth of 32GB/s which actually exceeds the best main memory bandwidth you'd get out of an Ivy Bridge CPU with very fast memory, so no, that's not a bottleneck for bandwidth, though yes, there is some latency there.
Its both, for my application, the GPU is roughly 3x-5x as fast as a high end CPU. This is fairly common on a lot of GPGPU workloads. The GPU provides a decent but not huge performance advantage.
But, we don't use the GPU! Why not? Because copying the data over the PCIe link, waiting for the GPU to complete the task, and then copying the data back over the PCI bus yields a net performance loss over just doing it on the CPU.
In theory, a GPU sharing the memory subsystem with the CPU avoids this copy latency. Nor does it preclude still having a parallel memory subsystem dedicated for local accesses on the GPU. That is the "nice" thing about opencl/CUDA the programmer can control the memory subsystems at a very fine level.
Whether or not AMD's solution helps our application remains to be seen. Even if it doesn't its possible it helps some portion of the GPGPU community.
BTW:
In our situation its a server system so it has more memory bandwidth than your average desktop. On the other hand, i've never seen a GPU pull more than small percentage of the memory bandwidth over the PCIe links doing copies. Nvidia ships a raw copy benchmark with the CUDA SDK, try it on your machines the results (theoretical vs reality) might surprise you.
Without sounding like too much of a jerk, I have hundreds of commits in the linux-2.6 fs/* tree. This is what I do for a living.
Well, then your part of the problem. Your idea that you have to be correct or fast is sadly sort of wrong. Its possible to be correct without completely destroying performance. I have a few commits in the kernel as well mostly to fix completely broken behavior (my day job in the past was working on an enterprise unix). So, I do understand filesystems too. Lately, my job has been to replace all that garbage, from the scsi midlayer up, so that a small industry specific "application" can both make guarantees about the data being written to disk while still maintaining many GB/sec of IO. The result, actually makes the whole stack look really bad.
So, I'm sure your aware that on linux, if you use proper posix semantics (fsync() and friends) the performance is abysmal compared to the alternatives. This is mostly because of the "broken" fencing behavior (which has recently gotten better but still is far from perfect) in the block layer. Our changes depend on 8-10 year old features available in SCSI to make the guarantees that aren't available everywhere. But it penalizes devices which don't support modern tagging, ordering and fencing semantics rather than ones that do.
Generally in linux, application developers are stuck either dealing with orders of magnitude performance loss, or they have to play games in an attempt to second guess the filesystem. Neither is a good compromise and its sort of shameful.
Maybe its time to admit linux needs a filesystem that doesn't force people to choose either abysmal performance, or no guarantees about integrity.
99% of software doesn't need to call fsync() on a sanely designed filesystem.
Really? please, show me the part of POSIX which says the data you wrote has now been flushed to the medium and you can respond with 100% certainty, to the user, or API making a request that if power fails this transaction will be safe.
Well, if linux is a toy (your basic argument) then why are all the subsystem maintainers paid by large companies a salary same as the developers at Microsoft, or any other OS company?
My point doesn't preclude people showing up and writing the next great filesystem. Its simply a question of why everyone thinks its a good idea for a guy PAID to maintain a filesystem to drop it and go write another one. If you worked for _BIG_ company and were paid to maintain their application, and you decided one day that maintaining their application was a PITA cause it was old crufty and not sexy anymore and instead refused to fix problems in it, rather spending the next 4 years writing a replacement (complete with another set of bugs) how long do you think your job would last?
Of course, this stuff happens in a lot of software projects, new developer shows up, and writes buggy new system cause they think they are smarter than the last guy. It frankly speaks of immaturity and an "artist" mentality rather than an engineering process. Sure, software isn't all engineering but linux is an OS, its a fundamental part of a computing platform and one that is expected to provide some basic level of service to applications (you know the things actually doing the work). When it fails at that, because its a patchwork of art, then you have to question why.
Ext3 is still chugging along and doing what you want. A filesystem that sacrifices everything for stability.
EXT3, is actually fairly good, and the performance isn't bad _EXCEPT_ for one issue. fsync(), which causes a massive IO barrier against all the other operations in the filesystem. fsync() should only be assuring the named file is consistent, and yet it basically stalls the entire FS to assure that one file. Its a problem with lack of proper IO tagging and actually is a fundamental problem with the block layer in linux. A recent LSML posting about SYNCHRONIZE CACHE hints at the problem too (complete device flush when only a small portion of the IO needs to be flushed).
No, that's FUD and/or misunderstanding on your part.
"data=ordered" is ext3/4's name for "don't expose stale data on a crash," something which XFS has never done,
Actually, I think your the one that doesn't understand how a journaling file system works. The problem with XFS has been that it only journals meta data, and the data portions associated with the metadata are not synchronized with the metadata updates (delayed allocation an all that). This means the metadata portions (filename, sizes, etc) will be correct based on the last journal update flushed to media, but the data referenced by that meta-data may not be.
A filesystem that is either ordering its meta data/data updates against a disk with proper barriers, or journing the data alongside the meta data doesn't have this problem. The filesystem _AND_ its data remain in a consistent state.
So, until your understand this basic idea, don't go claiming you know _ANYTHING_ about filesystems.
That will probably get 95% done before the next cool kid on the block takes over.
Filesystems on linux never seem to be 100% done. By that I mean, they are bulletproof and reasonably fast.
Just think, if instead of having dozens of primary fileystems (ext[2,3,4], reiserfs, ocfs, ocfs2, xfs, jfs. gfs2, zfs) over the last 15 years, someone had actually spent the time and designed/researched a general purpose filesystem, implemented and slogged through all the issues on one of them. Linux might have a good filesystem. The ext2/3 combination appeared to be on that path, but instead of fixing the fsync problems, and a couple other issues, it was basically abandoned in favor of ext4 which while maintaining the ability to mount ext3, and is named the same could have just been called "we took some bad ideas from XFS for performance reasons and now we have the same data integrity problems".
Your happy with XFS because your machine has never lost power or crashed. If either of those things happened with the older versions of XFS it was nearly a 100% guarantee you would lose data. Now i'm told its more reliable.
So, if you told me you have been running it for the last year and it was reliable I would have given you more credit than claiming you have been running it for a decade and its been reliable. Because, its had some pretty serious issues that if you didn't hit them means your not a good test case.
I'm still skeptical, because AKAIK, XFS still doesn't have an order data mode.
MS gave Word away.
I don't remember MS ever giving word away except at events, as they still do with much of their software. If anything it was darn expensive.
The reason Word won, has more to do with WordPerfect than Word. Wordperfect was THE DOS editor everyone used. But it was a real PITA, without the keyboard overlays it was impossible to learn to use. Oh, and formatting your output was a nightmare of control codes sprinkled all over the text which visually bore no resemblance to the output. To enjoy a modern version of the experience you could try TeX in emacs on a 80x25 terminal...
So, along comes word for windows, and its WYSIWYG (for the most part), and pretty much overnight everyone was like wow that rocks, except for a few die hard wordperfect lovers. Wordperfect responded to word for windows by writing the ugliest VGA application possible (version 6 BTW) which came out a good year or two after word for windows 2. It bombed because it was both SLOW and BUGGY and the WYSIWYG function was barely better than the print preview function they had in 5.1 aka, it was more like WYSIWY Might Get.
Meanwhile, windows was getting better, you could buy accelerated 16 bit video cards,etc and with each video card release windows apps looked better and ran faster. Plus the printer functions in windows were maturing and you could get nice fonts/etc for windows and print them on basically any printer. Unlike wordperfect which had limited fonts and printer support.
Eventually word 6 was released, which was a very nice piece of software and pretty bug free. By the time wordperfect came out with an even buggier windows version it was game over for them. Word was stable, fast and quite usable on windows.
The only real competitor at the time was Ami pro which didn't waste any time bringing a windows app to market.
though I'm trying to figure out how they didn't manage that back when it was 6% only a decade ago.
I don't know what state you live in, but if its like the one I live in the answer is easy and its three fold.
First the population of the state is expanding fairly rapidly, but the laws on new development don't require the developers to pay for the privilege of adding to city services (water/roads/electric). So, everyone moving into town is effectively subsidized by all the existing residents. Sure they have been paying for these services elsewhere, but they didn't bring them with them and they are left rusting/underutilized in places like Detroit.
Secondly, the state itself has been reducing business and franchise taxes as fast as possible. This in turn is reflected in the state paying a smaller percentage back to the communities for education/infrastructure/etc. The local communities then turn around and do the only thing they can, raise sales and property taxes and in many communities its insufficient to make up the shortfall.
Thirdly, the police forces have been expanding nationally at a frightening rate, and they are becoming significantly more expensive. 20 years ago police choppers, SWAT teams, armored vehicles, infrared cameras, etc were unheard of. Now every 3rd rate city in the country has a minor army. We don't even need the national guard anymore because the police force is like a second military. Combined with the fact that the police unions are the only unions in the country that haven't been destroyed by the 'R's means that its likely average salary for the officer handing out tickets is significantly above the salary of the general population. So the city budgets are overwhelmingly paid to the police departments. Librarians get laid off, and the police get a raise.
Only a bunch of ideologues or people complete ignorant of power generation would fail to count nukes as clean energy. When your "waste" after decades of use can be contained in a few shipping containers and used to generate more electricity then its cleaner than the manufacturing byproducts of equivilant "Green" energy sources. The ERI numbers for nukes are staying fairly constant, while even the numbers for coal/NG are going up.
At this point the planet would be better off if we irradiated 99% of it to Chernobyl levels. Simply because it would then be allowed to revert to a sustainable fairly natural state. The current state of affairs is going to be much worse.
Most of these systems are single purpose and fit in more as an embedded system than anything else.
So, what is the attack vector? Most of the XP exploits in recent memory are related to peoples browsing habits and pieces of the OS used by the browsers being susceptible.
So, the fact that people aren't surfing the web probably removes 99% of the threat, leaving the remaining possibilities of a worm on the internal network exploiting an open system service (network share etc) that could be blocked or disabled.
If an exploit is found in a direct system service like that I'm betting MS rolls out a security patch anyway. Probably, just to avoid the liability issues (same way you get recall notices on 20 year old cars if the problem is severe enough and considered a manufacturing defect).
Its only once the installed base drops below 5% or so would I guess that MS really stops supporting it for critical problems. Once that happens its not going to be a target for new exploits anyway.
I'm just wondering how long it takes before they stop doing activations. I have a copy of XP that has never been activated, I'm keeping around just to see what happens. I suspect they release a no authorization patch at some point but right now if they did it I'm sure XP installs would take off again.
For some reason I can't find the paper linked in that article. But accessing 64k devices is basically nothing, especially if they are a bunch of virtual mod3s and mod9's like just about every mainframe config I've seen. And really its less than 64k because your terminals, tapes, etc are also in that address space. Its like saying I have 4 Gigabytes of IO space and each adapter only takes 16 bytes of it. Useless BS information. Really, I was thinking about the address space issues on the mainframe last year, and came to exactly the opposite conclusion. Its a limitation, especially since the address space is shared between LPARs. AKA if you have 20 LPARs, with independent devices its actually only 4k devices per LPAR, which could be really limiting, especially if you can't run EAVs and the max capacity per volume is 54GB.
But the real problem is that even if you attached 256 devices on multiple 8Gbit ficon channels, the CEC to IO drawer interconnect is going to be the bottleneck. Thats assuming you can start enough ficon commands to keep each channel busy.
Here are real numbers from IBM on their ficon performance at 8Gbit (still current speed).
ftp://public.dhe.ibm.com/common/ssi/ecm/en/zsw03127usen/ZSW03127USEN.PDF
Go look at emulex's site. Their numbers are over an order of magnitude better and they offer a 16Gbit board too.
Anyway, did you ask EMC why the numbers were worse on your other platform? I'm betting you can "tweak" it up to speed too. Rarely is the machine the bottleneck when talking on a SAN. Its almost always the disk subsystem. Linux out of the box on nearly every platform needs "tweakage" Many of the fiber channel drivers on linux have very shallow queues and need to be significantly deeper for IOP benchmarks.