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Multicore Requires OS Rework, Windows Expert Says
alphadogg writes "With chip makers continuing to increase the number of cores they include on each new generation of their processors, perhaps it's time to rethink the basic architecture of today's operating systems, suggested Dave Probert, a kernel architect within the Windows core operating systems division at Microsoft. The current approach to harnessing the power of multicore processors is complicated and not entirely successful, he argued. The key may not be in throwing more energy into refining techniques such as parallel programming, but rather rethinking the basic abstractions that make up the operating systems model. Today's computers don't get enough performance out of their multicore chips, Probert said. 'Why should you ever, with all this parallel hardware, ever be waiting for your computer?' he asked. Probert made his presentation at the University of Illinois at Urbana-Champaign's Universal Parallel Computing Research Center."
'Why should you ever, with all this parallel hardware, ever be waiting for your computer?'
Because I/O is always going to be slow.
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The problem is that most (if not all) peripheral hardware is not parallel in many senses. Hardware in today's computers is serial: You access one device, then another, then another. There are some cases (such as a few good emulators) which use muti-threaded emulation (sound in one thread, graphics in another) but fundamentally the biggest performance kill is the final IRQs that get called to process data. The structure of modern day computers must change to take advantage of multicore systems.
Since when have OS designers optimised their code to milk every cycle from the available CPUs? They haven't, they just wait for hardware to get faster to keep up with the code.
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Windows explorer sucks. It always just abandons copies after a fail - even if you're moving thousands of files over a network. Yes, you're left wondering which files did/didn't make it. It's actually easier to sometimes copy all the files you want to shift locally, then move the copy, so that you can resume after a fail. It's laughable you have to do this, however.
But it's not a concurrency issue, and neither, really, are the first 2 problems you mention. They're also down to Windows Explorer sucking.
For that matter, since when have software vendors been willing to pay architects/designers/engineers etc to optimise their software to milk every cycle from the available CPUs and provide useful output with the minimum of effort? They don't, they just wait for hardware to get faster to keep up with code.
The only company that I have personally been exposed to that gives half a hoot about efficient performance is Google. It annoys me beyond belief that other companies think it's acceptable to make the user wait for minutes whilst the system recalculates data derived from a large data set, and doing those calculations multiple times just because a binding gets invoked.
Science advances one funeral at a time- Max Planck
Well - I can tell you that Dave Probert saw his first multi-processor about 28 years ago at Burroughs corporation. It was a dual-processor B1855. I had the pleasure with working with the guy way back then. From what I recall he then went on to work at FPS systems which was an array processor that you could add onto other machines (I think vaxen...but I could be wrong there..)
Anyway - he has been around ALONG time.
Have you compiled your kernel today??
I love how Microsoft can come along in 2010 and with a straight face say it's about time they took multiprocessing seriously. Or say it's about time we started putting HTML5 features into our browser. And we're finally going to support the ISO audio video standard from 2002. And by the way, it's about time we let you know that our answer to the 2007 iPhone will be shipping in 2011. And look how great it is that we just got 10% of our platform modernized off the 2001 XP version! And our office suite is just about ready to discover that the World Wide Web exists. It's like they are in a time warp.
I know they have product managers instead of product designers, and so have to crib design from the rest of the industry, necessitating them to be years behind, but on engineering stuff like multiprocessing, you expect them to at least have read the memo from Intel in 2005 about single cores not scaling and how the future was going to be 128 core chips before you know it.
I guess when you recognize that Windows Vista was really Windows 2003 and Windows 7 is really Windows 2005 then it makes some sense. It really is time for them to start taking multiprocessing seriously.
I am so glad I stopped using their products in 1999.
If we want efficient code, we have to figure out ways to reward the programmers that write it. I don't see any sign that people anywhere are interested in doing this. Anyone have suggestions for how it might be done?
It's happening, from a source people didn't expect: portable devices. Battery life is becoming a primary feature of portable devices, and a large fraction of that comes from software efficiency. Take your average cell phone: it's probably got a half dozen cores running in it. One in the wifi, one in the baseband, maybe one doing voice codec, another doing audio decode, one (or more) doing video decode and/or 3d, and some others hiding away doing odds and ends.
The portable devices industry has been doing multi-core for ages. It's how your average cell phone manages immense power savings: you can power on/off those cores as necessary, switch their frequencies, and so on. They have engineers who understand how to do this. They're rewarded for getting it right: the reward is it lives on battery longer, and it's measurable.
Yes, you can get lazy and say 'next generation CPUs will be more efficient', but you'll be beaten by your competitors for battery life. Or, you fit a bigger battery and you lose in form factor.
The world is going mobile, and that'll be the push we need to get software efficient again.
I've always thought that both data flow languages and fortran95 had some innovations for multi-core programming worthy of being copied.
Data flow languages such as "G" which is sold as national instruments "labview" brand are intrinsically parallel at many levels. What they do is look at a function call as a list of unsatisfied inputs. These inputs are waiting for the data to arrive to make the variables valid. Then the subroutine fires. Thus every single function is potenitally a parallel process. it's just waiting on it's data. If you program in a serial fashion then of course those functions get called serially. But with graphic programming in 2D, you almost never are programming serially. You are just wiring outputs of other functions to inputs of others. Serial dependencies do arise but these are asynchronous and localized cliques. everything else is parallel. Yet you never ever ever actually write parallel code. it just happens automatically. Perl data language had a glimpse of this but it's not the same thing since the language is still perl and thus not parallel.
Objective-C with it's "message passing" abstraction is perhaps getting closer to the idea of a data flow. While one might complain that well objective-C message passing is just a different sugar coating of C just like C++ is. This would be true from the user's point of view. But it's not as true from the Operating system's point of view. IN OSX, these messages are passing more like actual socket programming at the kernel level. So there's more to objective C on apple's than meets the eye. But I don't know how far you can push that abstraction.
In fortran there are some rather simple but powerful multi-processor optimizations. First there's loops like "forall" that designate that a loop can be done in any order of the loop index and even in parallel. and then there's vectorized statements as part of the language like matrix multiplies. those are rather simple things so don't solve much but they do show that you can put a lot of compiler hinting into the language itself without re-inventing the language.
Some drink at the fountain of knowledge. Others just gargle.
Citation needed? I think you'll find that Iphone only appears to outperform Android because Android is doing a lot more then the Iphone. Further more many things that work on Android do not work on Iphone, slashdot for instance works fine on my HTC Dream or newer Motorola Milestone with the standard browser, it works even better with Dolphin browser.
This cannot be a fair comparison until the Iphone can do everything that Android phones can, unless you want to compare functionality where Iphone is an epic failure.
Now I can tell you're full of it. All prices are incl of local taxes, and UK VAT does not apply outside the EU for those in Australia, Canada and the US.
UK Expansys
Motorola Milestone GBP 379
Nexus 1 GBP 599
Iphone 32 GB GBP 799
AU Mobicity
Motorola Milestone A$659
Nexus 1 A$849
Iphone 16 GB A$959
The cheapest Iphone 3GS available is A$100 more expensive then the newer Motorola Milestone (droid for the Yanks) and Google Nexus One. Not to mention that both the Milestone and Nexus One can do more as well as lack the restrictions of the Iphone. But then again I suspect you were merely looking to confirm your quite obvious bias rather then do an accurate comparison.
Apple's operating systems are not very well optimised, not even as much as Windows operating systems, Apple's OS pretend to have optimisation by providing the OS with more hardware then it needs and limiting functionality to prevent any perceived loss of speed. Most people using a Mac or Iphone rarely use the full power of the hardware, ergo an un-optimised OS goes unnoticed by the user. Here is the core of the design (in an engineering perspective) a design does not have to work well, it just has to work. The vast majority of people will ignore tiny flaws if they can get the task done, OTOH if a computer doesn't do the task the user will get annoyed no matter how pretty the interface.
As a good developer friend of mine likes to say, "If given the choice, a user will press the 'I just want it to work today' button". OSX provides this very shiny button but only in a few select places, Windows provides this not so shiny button almost everywhere. This is why Windows is still the number one OS on the planet.
Calling someone a "hater" only means you can not rationally rebut their argument.