Linux threads are fine. The following letter may be a good thing to point to. And here is a follow-up.
The basic story is that Linux, unlike most operating systems, does not have a hard distinction between a thread and a process. Instead it has the idea of a context of execution, and with the clone() call a context of execution can reproduce a copy of itself, and decide how much is copied. The last is important, clone() can be anything from spawning another thread to a traditional fork.
This threading model is somewhat different than what most operating systems provide, but it is quite sufficient to provide a full POSIX thread implementation with very good speed on a context-switch between threads or processes. (In fact Linux does a faster context switch between processes than most operating systems do switches between threads on the same hardware.)
By contrast NT has a different problem. NT has tremendous difficulty with processes. The time to create a process is abysmal. Context switches are not cheap. And once you start paging, the paging algorithm has beeen found to literally worse than straight chance!
However NT has a pretty good time on context switches between threads and (on paper) some nice specs for working with them. But NT's threading model is somewhat different from the POSIX model and anyone who is experienced with Microsoft knows that what is on paper and what really happens are not always the same...
On 64-bit CPUs Linux loses the 2 GB limit on file-sizes. Plus 64-bit architectures are significantly better for dealing with large amounts of data. Not to mention the nice speed of an Alpha.
Unfortunately none of the "big boys" have released for the Alpha so you would need to use something like PostGres.
Another tip. If you use ext2, increase the block-size. By default it is 1k, if you bump that to 4k you may see a performance increase and you will see a big improvement in fsck. Of course long-term the right solution to fsck problems is to use a journalled file-system. And so at the moment you may not want to use Linux for this...
The government's announcement was a way to make it look like they were opening up while really trying to keep things under control. After all what did they say? "Approved code" would be allowed to be exported at any strength. Who does the approval? They do! And what else was in their announcement? Lots of verbiage about how important it is for law enforcement to be able to break encryption.
Can you say "secret key escrow" just like Clipper?
I knew you could!
So, of course, no open source software can possibly meet the guidelines. After all with open software anyone can see the back door and that would never do, would it?
I will check back tonight. A little disingenuous of you to claim that you can provide some examples from a textbook when no accurate textbook that I have seen contains such examples...
Yet another assertion without substance that some mysterious reference has the counter-arguments against Evolution, without anything to back it up.
I ask for flaws that you want presented and you can only come up with straw men like those?
Here, let me direct you at a reference for why there are and always will be gaps in the fossil record. And as for the birds, are you thinking of the se gulls? In which case your comment about dissecting the things is completely wrong. And while they make an extremely nice example, first of all do not be fooled into thinking that they are the only ring species. Besides which, there are lots of other reasons to believe in macro evolution. Or perhaps you forget what led Darwin to look at the theory of evolution?
Right, something completely different.
I am still waiting for a flaw that we are supposed to teach...
You probably read something like this misinterpretation of the evidence.
If you actually go and read the articles you will find that what they found evidence for is that all humans have mitochondria that trace back to a single individual several hundred thousand years ago. That means that if you trace us all back on direct matrilineal descent (mother to mother to mother to...) you will eventually arrive at a single person.
What they don't mention is that the scientists expected to find that. Think of direct matrilineal descent as being a bush that constantly branches (women have daughters) and gets pruned (some women have no daughters). Starting from a specific point in time, all that that says is that all of the other branches existing at that point have since been completely pruned. This could happen pretty easily by chance, particularly if you started with a small population that was successful and spread out and replaced other groups.
If this really contradicted evolution, then you would think that courses discussing it might be a little more worried than they are, wouldn't you...
In case it makes you feel better, I personally believe that most Creationists are uninformed but not necesarily fools. But that does not mean that their ignorance deserves to be taught as science.
I have encountered many claims of mysterious arguments that were supposed to be very persuasive. But I have yet to encounter one that is not in what you admit to be the category that 99.9% of them are in. Which is to say utter BS.
So rather than just say that such arguments exist, please give me tangible evidence for them. Otherwise I will have to relegate it as another "Just so" story to go with the Lady Hope lie. (She was the one who claimed to have been at Darwin's deathbed and that he renounced evolution and accepted God. His family claimed that she was not there and his actions do not fit with her claims either. But many people believe that "Even Darwin renounced Evolution in the end" but do not know the source of the story.)
It is about as believable as yet a Microsoft press release unless you can give me something resembling specifics...
First of all Columbus sailed over 500 years ago, not 400.
More importantly the argument brought against him (based on the Ptolemaic theory) was that the distance to China was too far and he would surely starve. And they were right! Had he not encountered a continent, he would have starved! (He was pretty close to it at that.)
As for what you said about my knowledge of evolution...put it this way. What you say shows charming faith in your world view. You did follow the link? If so then please explain to me about how series of transitional fossils (esp. ones showing things that Creationists think did not happen) can be shown to be as strongly evidence for Creationism as it is for evolution?
Similarly if I attempted to clear up some of your mis-conceptions, would that support the theory of creationism?
Come on, the theories are different and the differences are testable. The fact that the answers to the tests are not what you might want them to be are not my fault!
The loophole in QM allows non-conservation as long as it is below the limits of direct measurement. (You can measure statistical effects from it, but not direct events.)
To take an extreme case, general relativity allows time-machines to be built. Consider a box that passes backwards in time only to later on be passed into the machine. In other words there was a time when its energy did not exist, then it came through the warp, and then it went away again! This is a loophole through which one could (literally) drive a mack truck!
The truth of the matter is that the case for evolution is very strong and the basic theory has had no serious scientific challenges in 80 years. The common Creationist arguments are very weak and are generally based on misinformation, misunderstanding, and more than a few cases of outright deception.
None of us were around when the USA was purportedly founded! How can you teach that stuff as fact?
Ridiculous, isn't it? But the fact is that your argument against evolution is no less ridiculous to anyone who has bothered to learn about the subject. So why not get some basic information?
Serious scientists in fields connected in any way with Evolutionary theory do not seriously believe in Creationism. In fact the basic tenants of literal interpretations of Creationism were discredited as far back as the early 1800's when it was shown that there had been no World Flood covering England (and marks that had been taken as evidence for that were actually left by ice sheets). This predated Darwin considerably.
The fact is that not only are Creationist arguments wrong, they are incredibly bad and typically dishonest to boot! They range from faked data to deliberate misquotes to misunderstandings of basic physical laws!
Yet ignorant people will continue to assume that somehow Creationism is equivalent to Evolution. And - because they choose to remain ignorant - they will never learn differently.
It started off with a list of outrageous assertions, and then supported all of them.
Some of the worse ones?
If a fat man and a skinny man glide down the same hill on identical bikes, then all else being equal the fat man will reach the bottom first.
It is possible to reach temperatures below absolute zero.
Energy is not conserved.
They were right about all of these. Whether the answer has to do with air resistance, technical quantum mechanical definitions, or general relativity...
But I will never forget reading that list of assertions for the first time. I wish that they had kept it.:-(
What is forward, what is backwards? Evolution is about what works now, not some ideal. When the climate gets colder, things adapt or die. When it gets warmer, things adapt back. (Gould's essays have more than a little to say about this...)
This is a bad example If the distance from one brim to the other was 9.7 cubits, then the circumference is closer to 30 cubits than 31. Therefore, measuring to the nearest cubit, the figures given are perfectly legitimate.
(Even the alt.atheism FAQ dismisses this one as a red herring.)
The key to a lot of cracking attempts lies in getting specific information. Names of key servers. Names of people who have user accounts. Passwords. Descriptions of security provisions. That kind of thing.
Much of this is easiest to get on the phone. The same techniques that a real journalist uses to get at information that is not public knowledge, is the information that crackers use to break into systems. So stop and think about whether you manged to (or could have) obtain information that would help you break into the system. Said information can be as innocuous as knowing who the employees are, personal tidbits about current employees, that sort of thing.
Don't believe me? Well a common technique is to call someone up, pretending to be another employee. Pretending to be a real person that they person on the line is likely to have heard of is more likely to get you in. For instance you could call up and say, "Hey, this is Greg Watson over in accounting. I am looking for Bill Smith. Do you know where he is?... He just quit? Shoot. I was hoping he could get something for me..."
See? By knowing the name of someone who just left, someone who is still there, and someone in another department, you have an excellent chance of getting information that you should not have.
As for security, no, not all systems can be easily broken. Of course there are some people who if they want in, will get in. You have to expect that. But most of what you have to worry about are common yet easily exploitable holes. For instance a lot of companies trust Microsoft's VPN implementation. In fact it is about as secure as swiss cheese and cracks are fairly readily available.
As long as easy targets are readily available in large numbers, I would be more worried about terrorist attacks on them than I would about anything else. (Attacks against information sources can be very profitable as well. Infilterate a VPN. Sell the information to someone else...)
OK, it won't crash you but unless you have been good about ulimits the following shell script will lock any Linux box hard. (Heck, pretty much any Unix as well.)
Before running make sure that you have shut down everything that you care about. When you get tired of an unresponsive box, turn it off by hand.
Save the following as a shell script and execute it...
#!/bin/bash # Tie up some memory perl -e 'push @big, 1 while 1' & # Spawn another me and wait on it $0 # Oops, that one died, try again... $0 & # Stick around and keep trying to lock up the last process slot.. while ( sleep 1 ) do $0 & done
When you are out of RAM and out of process slots, you are SOL...
Cheers, Ben
PS Note that I am careful to have the processes "chain out". That is to avoid having a lot of processes trying to be created at the same time. (Confuses the scheduler and slows down the creation of new processes.)
Slashdot Mirror
Linux threads are fine. The following letter may be a good thing to point to. And here is a follow-up.
The basic story is that Linux, unlike most operating systems, does not have a hard distinction between a thread and a process. Instead it has the idea of a context of execution, and with the clone() call a context of execution can reproduce a copy of itself, and decide how much is copied. The last is important, clone() can be anything from spawning another thread to a traditional fork.
This threading model is somewhat different than what most operating systems provide, but it is quite sufficient to provide a full POSIX thread implementation with very good speed on a context-switch between threads or processes. (In fact Linux does a faster context switch between processes than most operating systems do switches between threads on the same hardware.)
By contrast NT has a different problem. NT has tremendous difficulty with processes. The time to create a process is abysmal. Context switches are not cheap. And once you start paging, the paging algorithm has beeen found to literally worse than straight chance!
However NT has a pretty good time on context switches between threads and (on paper) some nice specs for working with them. But NT's threading model is somewhat different from the POSIX model and anyone who is experienced with Microsoft knows that what is on paper and what really happens are not always the same...
Cheers,
Ben Tilly
I guarantee that you are not running that system on a Linux box.. :-)
But if you drop that specification, then I agree. Besides which I don't know if you would *want* to run a big database on Linux today.
Cheers,
Ben
Nobody should run publically accessible CGI scripts that don't have taint mode enabled. Just start off your scripts with
#!/path/to/perl -T
and fix everything that breaks.
You will close off a lot of security holes that way...
Ben
On 64-bit CPUs Linux loses the 2 GB limit on file-sizes. Plus 64-bit architectures are significantly better for dealing with large amounts of data. Not to mention the nice speed of an Alpha.
Unfortunately none of the "big boys" have released for the Alpha so you would need to use something like PostGres.
Another tip. If you use ext2, increase the block-size. By default it is 1k, if you bump that to 4k you may see a performance increase and you will see a big improvement in fsck. Of course long-term the right solution to fsck problems is to use a journalled file-system. And so at the moment you may not want to use Linux for this...
(Give the penguin time. It is still growing up.)
Cheers,
Ben
The government's announcement was a way to make it look like they were opening up while really trying to keep things under control. After all what did they say? "Approved code" would be allowed to be exported at any strength. Who does the approval? They do! And what else was in their announcement? Lots of verbiage about how important it is for law enforcement to be able to break encryption.
Can you say "secret key escrow" just like Clipper?
I knew you could!
So, of course, no open source software can possibly meet the guidelines. After all with open software anyone can see the back door and that would never do, would it?
:-(
Ben
I will check back tonight. A little disingenuous of you to claim that you can provide some examples from a textbook when no accurate textbook that I have seen contains such examples...
Yet another assertion without substance that some mysterious reference has the counter-arguments against Evolution, without anything to back it up.
Ben
Are you telling me that you are not uninformed? Evidence please.
Ben
I ask for flaws that you want presented and you can only come up with straw men like those?
Here, let me direct you at a reference for why there are and always will be gaps in the fossil record. And as for the birds, are you thinking of the se gulls? In which case your comment about dissecting the things is completely wrong. And while they make an extremely nice example, first of all do not be fooled into thinking that they are the only ring species. Besides which, there are lots of other reasons to believe in macro evolution. Or perhaps you forget what led Darwin to look at the theory of evolution?
Right, something completely different.
I am still waiting for a flaw that we are supposed to teach...
Ben
Behe's book is about abiogenesis, not evolution.
Anyways, if you are interested in the subject, why not start with some critiques (which lead to links both pro and con). Or a biologist's critique.
Cheers,
Ben
You claim that there are flaws with the basic theory. I have seen no evidence of that.
So please demonstrate your assertion by listing them.
Ben
You probably read something like this misinterpretation of the evidence.
If you actually go and read the articles you will find that what they found evidence for is that all humans have mitochondria that trace back to a single individual several hundred thousand years ago. That means that if you trace us all back on direct matrilineal descent (mother to mother to mother to...) you will eventually arrive at a single person.
What they don't mention is that the scientists expected to find that. Think of direct matrilineal descent as being a bush that constantly branches (women have daughters) and gets pruned (some women have no daughters). Starting from a specific point in time, all that that says is that all of the other branches existing at that point have since been completely pruned. This could happen pretty easily by chance, particularly if you started with a small population that was successful and spread out and replaced other groups.
If this really contradicted evolution, then you would think that courses discussing it might be a little more worried than they are, wouldn't you...
Cheers,
Ben
That is basically what you are saying.
In case it makes you feel better, I personally believe that most Creationists are uninformed but not necesarily fools. But that does not mean that their ignorance deserves to be taught as science.
Sincerely,
Ben
I have encountered many claims of mysterious arguments that were supposed to be very persuasive. But I have yet to encounter one that is not in what you admit to be the category that 99.9% of them are in. Which is to say utter BS.
So rather than just say that such arguments exist, please give me tangible evidence for them. Otherwise I will have to relegate it as another "Just so" story to go with the Lady Hope lie. (She was the one who claimed to have been at Darwin's deathbed and that he renounced evolution and accepted God. His family claimed that she was not there and his actions do not fit with her claims either. But many people believe that "Even Darwin renounced Evolution in the end" but do not know the source of the story.)
It is about as believable as yet a Microsoft press release unless you can give me something resembling specifics...
Ben
First of all Columbus sailed over 500 years ago, not 400.
More importantly the argument brought against him (based on the Ptolemaic theory) was that the distance to China was too far and he would surely starve. And they were right! Had he not encountered a continent, he would have starved! (He was pretty close to it at that.)
Don't believe me?
As for what you said about my knowledge of evolution...put it this way. What you say shows charming faith in your world view. You did follow the link? If so then please explain to me about how series of transitional fossils (esp. ones showing things that Creationists think did not happen) can be shown to be as strongly evidence for Creationism as it is for evolution?
Similarly if I attempted to clear up some of your mis-conceptions, would that support the theory of creationism?
Come on, the theories are different and the differences are testable. The fact that the answers to the tests are not what you might want them to be are not my fault!
Ben
The loophole in QM allows non-conservation as long as it is below the limits of direct measurement. (You can measure statistical effects from it, but not direct events.)
To take an extreme case, general relativity allows time-machines to be built. Consider a box that passes backwards in time only to later on be passed into the machine. In other words there was a time when its energy did not exist, then it came through the warp, and then it went away again! This is a loophole through which one could (literally) drive a mack truck!
Cheers,
Ben
As in the talk.origins FAQs.
The truth of the matter is that the case for evolution is very strong and the basic theory has had no serious scientific challenges in 80 years. The common Creationist arguments are very weak and are generally based on misinformation, misunderstanding, and more than a few cases of outright deception.
Sincerely,
Ben Tilly
None of us were around when the USA was purportedly founded! How can you teach that stuff as fact?
Ridiculous, isn't it? But the fact is that your argument against evolution is no less ridiculous to anyone who has bothered to learn about the subject. So why not get some basic information?
Sincerely,
Ben Tilly
Serious scientists in fields connected in any way with Evolutionary theory do not seriously believe in Creationism. In fact the basic tenants of literal interpretations of Creationism were discredited as far back as the early 1800's when it was shown that there had been no World Flood covering England (and marks that had been taken as evidence for that were actually left by ice sheets). This predated Darwin considerably.
Why not educate yourself a little?
Ben
Go off, read some FAQs...
The fact is that not only are Creationist arguments wrong, they are incredibly bad and typically dishonest to boot! They range from faked data to deliberate misquotes to misunderstandings of basic physical laws!
Yet ignorant people will continue to assume that somehow Creationism is equivalent to Evolution. And - because they choose to remain ignorant - they will never learn differently.
*sigh*
Some of the worse ones?
They were right about all of these. Whether the answer has to do with air resistance, technical quantum mechanical definitions, or general relativity...
But I will never forget reading that list of assertions for the first time. I wish that they had kept it.
Cheers,
Ben
What is forward, what is backwards? Evolution is about what works now, not some ideal. When the climate gets colder, things adapt or die. When it gets warmer, things adapt back. (Gould's essays have more than a little to say about this...)
Cheers,
Ben
This is a bad example If the distance from one brim to the other was 9.7 cubits, then the circumference is closer to 30 cubits than 31. Therefore, measuring to the nearest cubit, the figures given are perfectly legitimate.
(Even the alt.atheism FAQ dismisses this one as a red herring.)
Cheers,
Ben
Or whoever Jane has do that...
... He just quit? Shoot. I was hoping he could get something for me ..."
The key to a lot of cracking attempts lies in getting specific information. Names of key servers. Names of people who have user accounts. Passwords. Descriptions of security provisions. That kind of thing.
Much of this is easiest to get on the phone. The same techniques that a real journalist uses to get at information that is not public knowledge, is the information that crackers use to break into systems. So stop and think about whether you manged to (or could have) obtain information that would help you break into the system. Said information can be as innocuous as knowing who the employees are, personal tidbits about current employees, that sort of thing.
Don't believe me? Well a common technique is to call someone up, pretending to be another employee. Pretending to be a real person that they person on the line is likely to have heard of is more likely to get you in. For instance you could call up and say, "Hey, this is Greg Watson over in accounting. I am looking for Bill Smith. Do you know where he is?
See? By knowing the name of someone who just left, someone who is still there, and someone in another department, you have an excellent chance of getting information that you should not have.
As for security, no, not all systems can be easily broken. Of course there are some people who if they want in, will get in. You have to expect that. But most of what you have to worry about are common yet easily exploitable holes. For instance a lot of companies trust Microsoft's VPN implementation. In fact it is about as secure as swiss cheese and cracks are fairly readily available.
As long as easy targets are readily available in large numbers, I would be more worried about terrorist attacks on them than I would about anything else. (Attacks against information sources can be very profitable as well. Infilterate a VPN. Sell the information to someone else...)
Cheers,
Ben
It is customary to ask people who their influences were. But I would like to turn that around. and ask a harder question...
Which new authors do you feel that you have most strongly influenced? What specifically makes you select them?
Thanks,
Ben
OK, it won't crash you but unless you have been good about ulimits the following shell script will lock any Linux box hard. (Heck, pretty much any Unix as well.)
/bin/bash
Before running make sure that you have shut down everything that you care about. When you get tired of an unresponsive box, turn it off by hand.
Save the following as a shell script and execute it...
#!
# Tie up some memory
perl -e 'push @big, 1 while 1' &
# Spawn another me and wait on it
$0
# Oops, that one died, try again...
$0 &
# Stick around and keep trying to lock up the last process slot..
while ( sleep 1 )
do
$0 &
done
When you are out of RAM and out of process slots, you are SOL...
Cheers,
Ben
PS Note that I am careful to have the processes "chain out". That is to avoid having a lot of processes trying to be created at the same time. (Confuses the scheduler and slows down the creation of new processes.)