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Message 14527 - Posted: 28 Jan 2010 | 18:02:13 UTC

A while back there was some discussion about the slowdown of the GPUGRID app in Windows 7 compared to XP. Some of us noticed that when upgrading our OSes to Win7 the WU times increased significantly. It affected both compute 1.1 and 1.3 cards. Both Win7 32bt and 64bit exhibited the slowdown. As far as I know we never received an answer about why this is occurring.

To test this phenomenon I set up a dual boot machine, clean installs of WinXP-64 and Win7-64. The card is an MSI GTX 260 216 55nm. After running many WUs the result is that Win7 is consistently and equally slow compared to XP with every WU type. As an example I'll use the GIANNI_BIND WUs. Over the test period Win7 averaged 30,750 seconds for this type of WU. WinXP averaged 27,100 seconds. That's over an hour of wasted GPU time/WU in Win7. I tried driver versions 191.07, 195.62 and 196.21 with no appreciable difference in performance.

I did not try Vista as I have never run it and have no desire to. Also of note is that I found no slowdown with Win7 in any other project, GPU or CPU. Many, many projects were tested. A few actually showed a speed increase for Win7.

What could be causing this consistent and very appreciable slowdown in Win7 GPU processing for GPUGRID?

Regards/Beyond

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Message 14587 - Posted: 29 Jan 2010 | 0:39:27 UTC - in response to Message 14527.
Last modified: 29 Jan 2010 | 0:50:58 UTC

Exactly when did you do these tests?
How did you come to the conclusion that Win7 is slower for GPUGrid?
What assumptions did you make and what was the determination methodology?

Assuming your tests were solid and the results firm, I would speculate that it could be the case that it is slower on your particular system only; perhaps due to your AMD Athlon II X4 620 Processor not having L3 cache on that or perhaps it does not quite have enough RAM (64bit systems utilise more RAM, especially W7). You could well have unwanted services running (indexing services, defrags, aero, updates downloading, AV, you left a CD in, or it could be going into a low power mode). Perhaps you were even just using the computer more when W7 was running, or indeed perhaps your right, it is slower!

You should note that not all tasks are the same, some will take longer to run. Just look at your own results for your XP with the GTX 260; some tasks took 22000s and some 39000s. So if you ran 6 tasks on XP and 6 on W7 there is a fair chance that your average would not be an accurate conclusion. To be reasonably sure of your conclusions you would really need to run over 20 tasks on each system, from the same batch and see a constant and considerable change.
How much RAM do you have and what else is running?

This would lead me to believe you did your tests some time ago,

1697533 1056661 2 Jan 2010 5:15:54 UTC 2 Jan 2010 5:16:20 UTC Aborted by user 0.00 0.00 0.00 --- Full-atom molecular dynamics v6.71 (cuda23) 1692439 1056889 31 Dec 2009 16:20:59 UTC 31 Dec 2009 18:49:49 UTC Aborted by user 0.00 0.00 0.00 --- Full-atom molecular dynamics v6.71 (cuda23) 1690691 1056954 31 Dec 2009 4:11:44 UTC 31 Dec 2009 4:12:19 UTC Aborted by user 0.00 0.00 0.00 --- Full-atom molecular dynamics v6.71 (cuda23) 1690528 1057073 31 Dec 2009 3:03:22 UTC 31 Dec 2009 4:11:44 UTC Aborted by user 0.00 0.00 0.00 --- Full-atom molecular dynamics v6.71 (cuda23) 1687348 1056841 30 Dec 2009 7:05:13 UTC 30 Dec 2009 7:07:18 UTC Error while computing 2.10 0.06 0.00 --- Full-atom molecular dynamics v6.71 (cuda23) 1686462 1056695 30 Dec 2009 2:12:03 UTC 30 Dec 2009 7:02:13 UTC Error while computing 1.72 0.09 0.00 --- Full-atom molecular dynamics v6.71 (cuda23) 1685947 1057022 30 Dec 2009 0:35:14 UTC 30 Dec 2009 2:12:03 UTC Aborted by user 0.00 0.00 0.00 --- Full-atom molecular dynamics v6.71 (cuda23) 1229528 762768 9 Sep 2009 14:57:56 UTC 9 Sep 2009 18:04:22 UTC Aborted by user 0.00 0.00 0.00 --- 1162029 720687 26 Aug 2009 7:51:30 UTC 26 Aug 2009 16:23:18 UTC Error while computing 0.00 6.95 0.03 --- 936886 602381 8 Jul 2009 12:15:05 UTC 9 Jul 2009 14:49:12 UTC Aborted by user 0.00 62.94 3,977.21

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Message 14797 - Posted: 29 Jan 2010 | 17:10:16 UTC - in response to Message 14587.

Exactly when did you do these tests?
How did you come to the conclusion that Win7 is slower for GPUGrid?
What assumptions did you make and what was the determination methodology?

Did you carefully read my post?

You could well have unwanted services running (indexing services, defrags, aero, updates downloading, AV, you left a CD in, or it could be going into a low power mode).

None of the above. I'm not an idiot. I've spent 2 decades in IS. No Aero, no indexing, no low power mode, no CD, automatic updates turned off, no defrags, tested with no AV and then with Arira - no diference at all.

Assuming your tests were solid and the results firm, I would speculate that it could be the case that it is slower on your particular system only; perhaps due to your AMD Athlon II X4 620 Processor not having L3 cache on that or perhaps it does not quite have enough RAM (64bit systems utilise more RAM, especially W7). Perhaps you were even just using the computer more when W7 was running, or indeed perhaps your right, it is slower!

The system that the extensive tests are/were run on has 4GB ram It runs various CPU projects. Machine is a dedicated cruncher, does nothing else but DC. I ran the tests initially several months ago and in the last few weeks did re-installs of the OSes and reran the tests. They involve many WUs. All my GPUGRID machines showed the same slowdown when Win7 was installed. Machines with up to 6MB 3rd level cache showed the same problem. Others reported the problem earlier. No one has ever provided an answer.

You should note that not all tasks are the same, some will take longer to run. Just look at your own results for your XP with the GTX 260; some tasks took 22000s and some 39000s. So if you ran 6 tasks on XP and 6 on W7 there is a fair chance that your average would not be an accurate conclusion.

Again, did you even read my post? The sample time comparison was for the GIANNI_BIND WUs. ALL WUs of similar types show the same slowdown when compared. Times for a given WU type are very consistent.

Lets avoid having an unthinking love affair with Win7, and not blindly defend it's honor. I like Win7 too, but would like to find out why this slowdown is occurring and try to resolve the problem. I'm wondering if it could be a compiler issue, but that's only conjecture. Instead of assuming that I'm doing something wrong, please run your own tests since you don't believe mine. It's easy to install a Win7 / WinXP dual boot machine so you can see for yourself.

The tests are valid. What I'm looking for is a reason for the slowdown.



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Message 14802 - Posted: 29 Jan 2010 | 17:38:28 UTC - in response to Message 14797.

My blind guess is immature GPU drivers in Win7. I'm seeing various small issues with the display driver here and there, and have even had one or two BSODs which (strange but true) I never had under Vista.

Something isn't optimized correctly and if I had to guess, I'd place my bet on the nVidia driver.

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Message 14804 - Posted: 29 Jan 2010 | 19:04:51 UTC - in response to Message 14802.

My blind guess is immature GPU drivers in Win7. I'm seeing various small issues with the display driver here and there, and have even had one or two BSODs which (strange but true) I never had under Vista.

Something isn't optimized correctly and if I had to guess, I'd place my bet on the nVidia driver.

I think you might be on to something here. I will definitely keep testing as new drivers are released.

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Message 14813 - Posted: 29 Jan 2010 | 23:31:37 UTC - in response to Message 14804.
Last modified: 29 Jan 2010 | 23:36:29 UTC

You asked for an opinion and used vague wording such as, A While Back, Some Of Us Noticed, After Running Many Work Units...
You could have said, 4 months ago, many people noticed a 12% drop in points, added a thread link, said your machines had high end CPUs, plenty of RAM, large HDDs, and you ran 25tasks on each setup, stated the applications tested – or similar.
You could have also added that you work in IT, and then I would have assumed you did not make any obvious mistakes. That said, when W7 first came out, none of us were W7 experts, it takes time to become familiar with a new Operating System. Even after using Vista, I found that quite a bit had changed, and W7 is much more like Vista than XP.
Your tests may well be Valid but you did not supply enough detail for me to determine this and decide for myself. It takes facts, figures and confirmation to gain credibility.
When W7 first came out, and windows updates were allowed to run, it would automatically download an older NVidia driver and replace any newer one you installed yourself! This is because Microsoft only releases more heavily tested versions of other vendor’s software, so they are usually several release versions behind. This may have been the issue, but I can only suggest possible causes. You probably already know that XP is totally different in build than Vista and W7 which share similar kernals. This may also be the reason, as could a chipset driver, Bios version, or an automatic system configuration setting.
I think after SP1 is released would be a good time to review.

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Message 14818 - Posted: 30 Jan 2010 | 2:39:04 UTC - in response to Message 14813.

You could have also added that you work in IT, and then I would have assumed you did not make any obvious mistakes. That said, when W7 first came out, none of us were W7 experts, it takes time to become familiar with a new Operating System. Even after using Vista, I found that quite a bit had changed, and W7 is much more like Vista than XP.

I think I provided enough if you actually read it. Long rambling posts that say nothing are not my style. Sorry.

Your tests may well be Valid but you did not supply enough detail for me to determine this and decide for myself. It takes facts, figures and confirmation to gain credibility.

Instead of falling all over trying to prove me wrong, why not offer a useful reason why this is happening. It is happening.
Please set up a dual boot machine and test it yourself.

When W7 first came out, and windows updates were allowed to run, it would automatically download an older NVidia driver and replace any newer one you installed yourself! This is because Microsoft only releases more heavily tested versions of other vendor’s software, so they are usually several release versions behind. This may have been the issue, but I can only suggest possible causes.

The same thing happens with ATI updates. As I pointed out in my first post I tested with 3 driver versions. Updates are only allowed manually.

You probably already know that XP is totally different in build than Vista and W7 which share similar kernals. This may also be the reason, as could a chipset driver, Bios version, or an automatic system configuration setting.
I think after SP1 is released would be a good time to review.

As I stated in my reply to Jeremy (which was by the way a well thought out suggestion), I will keep retesting from time to time when new updates and drivers appear. I will also retest when the new beta app becomes the standard.

I'm interested to know if this same behavior has been observed with Vista. I won't test it myself because Vista IMO was junk and should never have been released in the botched form in which MS delivered it. Thankfully it's on it's way out the door...

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Message 16752 - Posted: 2 May 2010 | 19:44:46 UTC
Last modified: 2 May 2010 | 19:45:49 UTC

Update and a link to the original thread on this topic:

http://www.gpugrid.net/forum_thread.php?id=1449

The update is that the situation hasn't improved. Win7 is still approximately the same amount slower than XP in GPUGRID with both the v6.03 and v6.72 apps and with NVidia drivers up to the current v197.45. The difference may be due to the fact that the GPU utilization is higher in XP than in Win7. No matter what driver or Win7 settings I've tried I can't get the GPU utilization to be anywhere near what it is in XP. If anyone has a solution to this I'd appreciate it.

Please, no long rambling replies that neither address the problem, deny the problem or that try to mask it with irrelevance.

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Message 16754 - Posted: 2 May 2010 | 20:13:16 UTC - in response to Message 16752.

Please, no long rambling replies that neither address the problem, deny the problem or that try to mask it with irrelevance.

How about short replies that do any of the above?

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Message 16756 - Posted: 2 May 2010 | 21:26:37 UTC - in response to Message 16754.

Please, no long rambling replies that neither address the problem, deny the problem or that try to mask it with irrelevance.

How about short replies that do any of the above?

Highly preferable :-)

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Message 16757 - Posted: 2 May 2010 | 22:46:00 UTC - in response to Message 16752.

The difference may be due to the fact that the GPU utilization is higher in XP than in Win7. No matter what driver or Win7 settings I've tried I can't get the GPU utilization to be anywhere near what it is in XP.



GPU utilization could well be the key to this problem, in my Q9300 system GPU usage while GPUGRID is running rarely gets up to 90% and most of the time is between 76% and 85%


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Message 16760 - Posted: 3 May 2010 | 0:26:22 UTC - in response to Message 16757.

Have you tried this?

Advanced system settings, Performance, Advanced, change from Programs to Background Services.
I think I remember a card ran faster in a Win Server 2008 than on Vista. This may be why (the server even had a lesser CPU).

Might be worth a run overnight to test against previous task times.
Best to restart system after such changes.

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Message 16768 - Posted: 3 May 2010 | 8:57:22 UTC - in response to Message 16760.
Last modified: 3 May 2010 | 8:57:51 UTC

Have you tried this?

Advanced system settings, Performance, Advanced, change from Programs to Background Services.
I think I remember a card ran faster in a Win Server 2008 than on Vista. This may be why (the server even had a lesser CPU).

Might be worth a run overnight to test against previous task times.
Best to restart system after such changes.


I'll give it a go but there is an obvious reason for slowdown whether it does in real world I don't know but its name is AERO
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Message 16777 - Posted: 3 May 2010 | 12:26:03 UTC - in response to Message 16768.

Yeah, AERO has to be turned off to have any hope of similar performances with Vista/W7.
I dont think its automatically installed on 2008servers.

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Message 16779 - Posted: 3 May 2010 | 13:46:40 UTC - in response to Message 16760.

Have you tried this?

Advanced system settings, Performance, Advanced, change from Programs to Background Services.
I think I remember a card ran faster in a Win Server 2008 than on Vista. This may be why (the server even had a lesser CPU).

Might be worth a run overnight to test against previous task times.
Best to restart system after such changes.

Gave it a try just after you posted, made no difference.

Yeah, AERO has to be turned off to have any hope of similar performances with Vista/W7.

Aero is off on all my crunchers but tried turning it on for a couple of them to test and it made no difference at all.

It really does seem to be directly related to the GPU usage. The higher the GPU usage, the faster GPUGRID performs. That's certainly not a surprise, but how to adjust it? In Collatz and MilkyWay there are settings that allow the GPU usage to be tweaked. They can very easily be made to run the GPU at 99%. We could use the same here. The project would gain a LOT.

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Message 16784 - Posted: 3 May 2010 | 14:52:40 UTC - in response to Message 16779.

The Windows Desktop Manager is a bit of a hog, but you cant turn that off!
Lots of page faults, and its high priority. Lots of high priority tasks on Vista/W7, not as many on XP (and SP2 is faster than SP3)!

Perhaps a minimum installation of W7 would help?

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Message 16789 - Posted: 3 May 2010 | 18:37:27 UTC - in response to Message 16784.

The Windows Desktop Manager is a bit of a hog, but you cant turn that off!
Lots of page faults, and its high priority. Lots of high priority tasks on Vista/W7, not as many on XP (and SP2 is faster than SP3)!

Then why do the other projects run at 99% GPU in both XP and Win7?

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Message 16791 - Posted: 3 May 2010 | 20:38:24 UTC - in response to Message 16789.

Well, lets look at the difference between GPUGrud tasks and other tasks.

Firstly, GPUGrid uses NVidia cards (obviously), most other projects either use ATI or both (but are not so hot when it comes to NVidia cards)!

Most other projects have smaller tasks,

and most other projects use less CPU.

As the CPU usage on Vista/W7 for GPUGrid is set to below normal priority, while the many OS tasks are set to High Priority, and there are many, so they do keep interupting, perhaps that is the problem; not that the GPUGrid tasks are low, just that there are so many (and usually unnessasary) high Vista/W7 OS tasks that GPUGrid tasks dont get enough of a look in.

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Message 16825 - Posted: 4 May 2010 | 21:54:08 UTC

Same Problem here with Win 7 64bit and one 480 card, it's taking about 9 minutes to do one WU and that is mildly overclocked to 1600 Shaders

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Message 16914 - Posted: 8 May 2010 | 20:44:44 UTC

Well, the lower GPU utilization is a consequenze of the problem, not the reason.

Vista / 7 require completely rewritten graphics drivers. It could well be something small nVidia changed and possibly didn't notice, because it doesn't affect most apps.

When I switched from XP 32 to Win 7 64 I had a problem with MW on my ATI: performance dropped by ~30%. First I solved it by leaving one core free. That brought the speed back up to XP level and GPU utilization back to 99%. Now I've set "b-1" in Gipsels app_info to modify the polling behaviour. By doing this the app waits the estimated time and then polls the GPU continously. Luckily MW is very regular, so this uses some more CPU but otherwise works very well. Now I can use all CPU cores again.

Someone could test this by either freeing one core or by using the new swan_sync=1 option to extract maximum GPu performance. If in the latter case the difference is still there I suggest it has nothing to do with the OS, setup, services Aero etc. but rather with the driver itself. After all, the driver is still responsible for compiling the high level shader language code into machine code for the GPU - a rather complex process.

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Message 16918 - Posted: 8 May 2010 | 22:38:12 UTC - in response to Message 16914.

I think the problem with W7 is the driver (or other Vista/Win7 drivers that change GPU/Motherboard power saving settings). NVidia dont even support Win 2003 server or Win 2008 server! A poor show by NVidia.

swan_sync=0 enables the use of one CPU (actually, I think it removes paramiters that restrict the CPU usage)?!?

- Paramiter is tested and works better with 6.10.73 and 6.10.72 tasks.

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Message 16923 - Posted: 9 May 2010 | 10:49:11 UTC

Judging by [rl=http://www.gpugrid.net/forum_thread.php?id=2129&nowrap=true#16920]this[/url] post the CPU polling is not the cause. So it's just plain simply the different driver?

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Message 16925 - Posted: 9 May 2010 | 12:42:12 UTC - in response to Message 16923.

Judging by [rl=http://www.gpugrid.net/forum_thread.php?id=2129&nowrap=true#16920]this[/url] post the CPU polling is not the cause. So it's just plain simply the different driver?

MrS

Let me fix that url:

>> I do have SWAN_SYNC=0 enabled and both cards definitely have their own CPU thread. I'm not
>> using my CPU for anything else except browsing the forums with Firefox. My CPU is only at 3.4ghz.
>> My gpu usage on both cards is hovering around 55-57% at all times. Win7 x64 is just slow.

http://www.gpugrid.net/forum_thread.php?id=2129&nowrap=true#16920

Maybe it's the driver. One clue may be that the ATI apps MW & Collatz run at 99% in both XP & Win7. DNETC sometimes does and sometimes doesn't, but I'd say it's not that well programed at this stage. The the more I compare the two, the more I keep moving to ATI. It used to be that a big NVidia advantage was that their drivers were better, now that's turned around. The ATI drivers seem bulletproof and NVidia not so much. The only app that I can see buying NVidia for is GPUGRID, and with all the WU availability problems here concerning v6.72, etc. I'm becoming less enthusiastic.

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Message 16931 - Posted: 9 May 2010 | 19:10:51 UTC - in response to Message 16925.

Ups.. thanks!

BTW: MW and CC run so well (99%) because they're so simple - it's just the same small loop over and over again, just with different numbers. Massively parallel and not really constrained by memory bandwidth. It's the absolute best case scenario for GPU code. It's not as straight forward for GPU-Grid, e.g. you have to finish one time step before you can execute the next one and you're more memory bandwidth bound. I don't know how this utilization is calculated - does it count "waiting for memory" as busy (because they SM can't do anything else right now) or is it idle time (because it's not doing anything useful)?

ATI isn't a magical bullet. Just look how hard it's been to make GPU-Grid on a current gen ATI run half as fast as a previous gen nVidia.

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