None of the details you mentioned prevent you from writing a realtime application. To avoid indeterminate swap-in time, you mlock your application (which mlocks any linked libraries as well, so keep your library usage tight). Any IO the application needs should be offloaded to non-realtime threads. You can do it, it just requires competence. Just as programming in a "proper" realtime operating system does.
...Linux does have a RT version, in part supported by Ingo Molnar and Theodore Ts'o, but it does not see heavy use. In part, this has been because for a realtime OS to be successful, all the parts have to play ball, not just some...
Not really, the actual requirement is that nothing can block a real time process, which I believe the linux real time patches do in fact achieve quite reliably. It isn't important whether Firefox hangs up for a while, to anybody except the Firefox user. Perhaps realtime Linux has maximum latency higher than QNX (nobody has posted benmarks so far...) but certainly well within the range required for real time control of noncritical systems.
The real reason that the realtime patch set is not wildly popular is that a lot of devs and users tend to labor under the misaprehension that real time response isn't needed, because after all, their computer works pretty well without it. Actually, it doesn't as anybody involved with professional quality audio can attest, and if said users and devs would quit eding away the the evidence of their own eyes, they would notice frequent instances of nasty, unacceptable interactive latency. Amazing how selective memory works, isn't it?
For critical systems like engine and braking control, it is obvious that a "pure" realtime control system is needed, and be running on its own dedicated processor. For that, even QNX is arguably too complex, and too difficult to analyze to the extent required. But such critical systems have now become just a small part of what is going on in a modern car, with all the nav, infortainment, climate control, etc. For all this big bloaty stuff, realtime Linux is perfectly appropriate and would probably be a better choice overall than QNX due to the far greater range of hardware supported, more networking protocols, more nifty accelerators for applications, etc etc. Regards of whether Linux is the best choice (it is) QNX is still a damn good choice. Light years beyond anything Microsoft has had their fat hands in.
Probably avisable to save your posting effort... keep in mind that this is the guy who thinks it makes sense to floor it in the hope that the deer hits him in the side of his car instead of the front.
Going faster in the hope that an animal won't have time to jump out in front of you would amount to epic idiocy. Think about the much larger hole in the front of your car, the blood and guts splattered over your hood and grill, the possibility of going into the ditch because the animal went under your wheels. Keep in mind that kinetic energy increases as the square of the velocity. That curve goes vertical fast. When risk of hitting an animal exists, then slow down. Period.
Only a complete idiot would want the children to learn cursive. It's useless. I'm glad they stopped teaching art as well.
They can learn cursive in art class, or maybe archaeology. For practical purposes, printing is superior - easier to read and nearly as fast to write, with some practice. It was sad to see quill pens go, no? But we got over it.
The question is, will we get to a point where it won't matter? There will be a point where solid state drives will be cheap enough that you'll be able to get enough storage at a low enough price that people generally won't care. For example, if $50 got you a 500GB SSD or a 2TB hard disk, how many people would pick the hard disk? Even then, those who want more storage might just pony up the extra cash.
You seem to be limiting your thinking to consumer storage. Think data center, where even a small cost per byte saving can drive the engineering decision. With the quasi-panic migration to the cloud currently underway, data centers will make up an increasing slice of the pie, including offloading a lot of consumer computing. In the cloud, the long access time of spinning media usually does not matter, it is small compared to other lags. In the cloud, most data storage is bulk data, simply because there is more bulk data. It is going to be many years before any operator that needs to be competitive will be able to afford a wholesale migration to flash.
6TB for $300 is $50 per terabyte, while current pricing is around $400 per terabyte. That's a factor of 8, not 16. I based my math on 18 month doubling...
I stand corrected, the price differential has narrowed recently, however a factor of eight (8.4, more accurately) is still plenty big enough to keep flash out of many mass storage applications. This relationship whill gradually change, but it will take a lot more than 6 years to erode rotating media's share of mass storage to something similar to tape, say, where economies of scale start to be eroded. Just pulling a number out of my ass, I think we are looking at 15-20 years before rotating disks start looking like the tape market. After all, you're still going to want a hard disk to store your bootleg videos.
...today's rotating drive prices are almost completely based on the cost of the electronics and a single head/single platter mechanical system. You can't make a rotation drive significantly cheaper than today, but with each generation of SSD they can halve the number of NAND packages, shrink the PCBA, build controllers with fewer channels, etc...
And magnetic media continues to improve its linear and areal density at a rate not much different from improvements in flash density, largely maintaining its cost differential vs flash. As I alluded to above, the net effect is to push magnetic media out of workstations (and personal devices), and also out of high value data center applications. However, the mass storage, archival, and heirarchical sectors that remain are huge and growing rapidly with no sign of slowing. This means that rotating media will not be going the way of punch cards for many years to come.
SSDs will likely get there in 3-5 years by Moore's law...
Moore's law does not predict prices, it predicts transistor density. Even if you permit yourself to conflate price with density, say there is a factor of 16 to make up, by Moore's predicted semiannual doubling, that is 8 years, not 3-5.
The big fat fly in the ointment is that process costs are rising dramatically and there are yield issues. Plus as you say, magnetic media technology is not standing still. I say, after 8 years have passed, the big price differential will still exist. By that time disks will have moved firmly to an archival/heirarchical role and a typical workstations will only have them as secondary storage, if at all. This will drive up production costs somewhat by eroding the economy of scale, but the world's archiving requirements pull in the other direction, which should put something of a floor under shipped volume. Where will that floor end up? Possibly permanently in the 10X range. Disks just aren't going to die if that happens.
...They have stopped trying to hold back change, because that outright failed....
No it didn't, you only have to look at Microsoft's balance sheet to know that. Microsoft will continue to do everything it possibility can to hold back change, for the simple reason that the status quo is that huge piles of profit continue to arrive every month for doing very little work. Microsoft will fight tooth and nail to maintain that status quo.
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None of the details you mentioned prevent you from writing a realtime application. To avoid indeterminate swap-in time, you mlock your application (which mlocks any linked libraries as well, so keep your library usage tight). Any IO the application needs should be offloaded to non-realtime threads. You can do it, it just requires competence. Just as programming in a "proper" realtime operating system does.
BTW, Microsoft minions are pretty much the only ones who bandy about the term "Linux zealot". Minion.
...Linux does have a RT version, in part supported by Ingo Molnar and Theodore Ts'o, but it does not see heavy use. In part, this has been because for a realtime OS to be successful, all the parts have to play ball, not just some...
Not really, the actual requirement is that nothing can block a real time process, which I believe the linux real time patches do in fact achieve quite reliably. It isn't important whether Firefox hangs up for a while, to anybody except the Firefox user. Perhaps realtime Linux has maximum latency higher than QNX (nobody has posted benmarks so far...) but certainly well within the range required for real time control of noncritical systems.
The real reason that the realtime patch set is not wildly popular is that a lot of devs and users tend to labor under the misaprehension that real time response isn't needed, because after all, their computer works pretty well without it. Actually, it doesn't as anybody involved with professional quality audio can attest, and if said users and devs would quit eding away the the evidence of their own eyes, they would notice frequent instances of nasty, unacceptable interactive latency. Amazing how selective memory works, isn't it?
For critical systems like engine and braking control, it is obvious that a "pure" realtime control system is needed, and be running on its own dedicated processor. For that, even QNX is arguably too complex, and too difficult to analyze to the extent required. But such critical systems have now become just a small part of what is going on in a modern car, with all the nav, infortainment, climate control, etc. For all this big bloaty stuff, realtime Linux is perfectly appropriate and would probably be a better choice overall than QNX due to the far greater range of hardware supported, more networking protocols, more nifty accelerators for applications, etc etc. Regards of whether Linux is the best choice (it is) QNX is still a damn good choice. Light years beyond anything Microsoft has had their fat hands in.
Microsoft employee much?
It's not C until it has designated initializers.
OP was equating intentionally using C with intentionally driving drunk. As a long time C hack (still am) I concur.
Most of the embedded projects I looked at recently seem to be in C++.
Word.
You know, Tizen is like Anrdoid, but more open than Android. Really. Samsung's open source group totally made that happen.
</sarcasm>
I bought a Moto G for my wife last week. Very impressed. Very. Especially with the price.
Soon, Apple's only remaining market niche will be your mom.
Probably avisable to save your posting effort... keep in mind that this is the guy who thinks it makes sense to floor it in the hope that the deer hits him in the side of his car instead of the front.
You seem to be denying physics.
Going faster in the hope that an animal won't have time to jump out in front of you would amount to epic idiocy. Think about the much larger hole in the front of your car, the blood and guts splattered over your hood and grill, the possibility of going into the ditch because the animal went under your wheels. Keep in mind that kinetic energy increases as the square of the velocity. That curve goes vertical fast. When risk of hitting an animal exists, then slow down. Period.
Only a complete idiot would want the children to learn cursive. It's useless. I'm glad they stopped teaching art as well.
They can learn cursive in art class, or maybe archaeology. For practical purposes, printing is superior - easier to read and nearly as fast to write, with some practice. It was sad to see quill pens go, no? But we got over it.
The question is, will we get to a point where it won't matter? There will be a point where solid state drives will be cheap enough that you'll be able to get enough storage at a low enough price that people generally won't care. For example, if $50 got you a 500GB SSD or a 2TB hard disk, how many people would pick the hard disk? Even then, those who want more storage might just pony up the extra cash.
You seem to be limiting your thinking to consumer storage. Think data center, where even a small cost per byte saving can drive the engineering decision. With the quasi-panic migration to the cloud currently underway, data centers will make up an increasing slice of the pie, including offloading a lot of consumer computing. In the cloud, the long access time of spinning media usually does not matter, it is small compared to other lags. In the cloud, most data storage is bulk data, simply because there is more bulk data. It is going to be many years before any operator that needs to be competitive will be able to afford a wholesale migration to flash.
So what happened to shingled, is it dead?
6TB for $300 is $50 per terabyte, while current pricing is around $400 per terabyte. That's a factor of 8, not 16. I based my math on 18 month doubling...
I stand corrected, the price differential has narrowed recently, however a factor of eight (8.4, more accurately) is still plenty big enough to keep flash out of many mass storage applications. This relationship whill gradually change, but it will take a lot more than 6 years to erode rotating media's share of mass storage to something similar to tape, say, where economies of scale start to be eroded. Just pulling a number out of my ass, I think we are looking at 15-20 years before rotating disks start looking like the tape market. After all, you're still going to want a hard disk to store your bootleg videos.
...today's rotating drive prices are almost completely based on the cost of the electronics and a single head/single platter mechanical system. You can't make a rotation drive significantly cheaper than today, but with each generation of SSD they can halve the number of NAND packages, shrink the PCBA, build controllers with fewer channels, etc...
And magnetic media continues to improve its linear and areal density at a rate not much different from improvements in flash density, largely maintaining its cost differential vs flash. As I alluded to above, the net effect is to push magnetic media out of workstations (and personal devices), and also out of high value data center applications. However, the mass storage, archival, and heirarchical sectors that remain are huge and growing rapidly with no sign of slowing. This means that rotating media will not be going the way of punch cards for many years to come.
SSDs will likely get there in 3-5 years by Moore's law...
Moore's law does not predict prices, it predicts transistor density. Even if you permit yourself to conflate price with density, say there is a factor of 16 to make up, by Moore's predicted semiannual doubling, that is 8 years, not 3-5.
The big fat fly in the ointment is that process costs are rising dramatically and there are yield issues. Plus as you say, magnetic media technology is not standing still. I say, after 8 years have passed, the big price differential will still exist. By that time disks will have moved firmly to an archival/heirarchical role and a typical workstations will only have them as secondary storage, if at all. This will drive up production costs somewhat by eroding the economy of scale, but the world's archiving requirements pull in the other direction, which should put something of a floor under shipped volume. Where will that floor end up? Possibly permanently in the 10X range. Disks just aren't going to die if that happens.
It's only wacky if you bet on it happening next year. But, soon enough.
How soon is soon enough? 5 years? 10 years? And on what physical principle does your argument rely?
Two out of three ain't bad.
Need I point out that QT has had cross platform OpenGL support for many years? In QT, this is mature, reliable, well integrated and easy to use.
Wow, +1 for the elegant analogy. You could extend that, and note that the incompetent boss is dead from the neck up.
...They have stopped trying to hold back change, because that outright failed....
No it didn't, you only have to look at Microsoft's balance sheet to know that. Microsoft will continue to do everything it possibility can to hold back change, for the simple reason that the status quo is that huge piles of profit continue to arrive every month for doing very little work. Microsoft will fight tooth and nail to maintain that status quo.