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Old 2009-11-06, 19:14   #1
willmore
 
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Aug 2002

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Default XP 32-bit to Win7 64-bit slowdown

Hello, all.

I've just 'upgraded' my main desktop from 32 bit XP to 64 bit Win7.

I coppied over my old Prime95 folder and installed the new 64 bit 25.9.4 (from 32 bit 25.9.4). And, now the itteration times are huge. 2x or 3x slower than XP was. Is there some incompatability going from 32 bit to 64 bit?

I've done this on an idle machine and I've used cpu-z to verify the cpu isn't being throttled, etc.

Under XP/32, I was getting ~32ms/iter with two threads per worker (Q6600@3.2GHz). Now, I'm seeing 65 and 91--which is odd that one pair and the other are so different in speed. I've played with the affinityscramble settings to make sure they're optimum and this is the *best* I could do.

Is something going wrong here? Should I finish these exponents with the 32 bit client or something? Maybe I should go test to see if he's still fast....
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Old 2009-11-06, 19:19   #2
joblack
 
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Quote:
Originally Posted by willmore View Post
Hello, all.

I've just 'upgraded' my main desktop from 32 bit XP to 64 bit Win7.

I coppied over my old Prime95 folder and installed the new 64 bit 25.9.4 (from 32 bit 25.9.4). And, now the itteration times are huge. 2x or 3x slower than XP was. Is there some incompatability going from 32 bit to 64 bit?

I've done this on an idle machine and I've used cpu-z to verify the cpu isn't being throttled, etc.

Under XP/32, I was getting ~32ms/iter with two threads per worker (Q6600@3.2GHz). Now, I'm seeing 65 and 91--which is odd that one pair and the other are so different in speed. I've played with the affinityscramble settings to make sure they're optimum and this is the *best* I could do.

Is something going wrong here? Should I finish these exponents with the 32 bit client or something? Maybe I should go test to see if he's still fast....
Perhaps you have some other win7 services running ... check out the taskmanager or the performance monitor to find out what's going on ...
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Old 2009-11-06, 19:48   #3
willmore
 
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Hey, joe, thanks for the input. I did check that. :) When I see dissimilar performance like that, it's the first thing that comes to mind--"Hey, something is using up part of that die, let's check it out."

But, sadly, that's not the case.

Here's what I've found. I have downloaded fresh from the source the 32 and 64 bit versions of 25.9 and 25.11. p95 config is two workers each with two threads--basically, one die per worker, so they're sharing the same 4M L2.

25.9/32 30.5 & 37.0
25.11/32 30.5 & 37.2
25.9/64 30.8 & 30.9
25.11/64 30.8 & 31.0

Now, these numbers aren't likely to be horribly accuract, but they show the difference I see. The 32 bit clients run one core a bit slower while the 64 bit cores seem fine.

Here's something even *more* interesting. To do my testing, I coppied my prime95 folder out of Program Files and onto the desktop. Running things there *immediately* sped things up. If I go back to the 25.9/32 that I have in the Program Files directory, I get 44.5 & 43.0. WTF? Wierd.

So, there seems to be some strange magic going on with the version in the Program Files directory. Maybe that'll provide someone with a clue as to what's going on. For now, I'm moving Prime95 out of Program Files and I'm using the 64 bit client. Very odd. But, at least it's partially solved.
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Old 2009-11-06, 20:39   #4
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Ok I tried it myself. First don't take the first 5 minutes after starting the system. There I have more delays than later. Secondly Windows 7 (as Vista) has some special features for the Program Files folders (transparent directory redirect, ...) so I imagine if you write in a folder (what a program in there shouldn't do anyway) windows has more protection (and so more delay). The obvious solution is to move the Prime95 folder to another place (for instance your profile (c:\users\$yourname\blabla). I have moved it to c:\Prime95 ... I haven't found a major perfomance difference between the Program Files folder and another folder but I also haven't made any longterm test (there could be a difference). Also keep in mind that any process running in the background (firewall, antivirus, STEAM, Skype, ...) is stealing processor cycles and you probably don't see it in the Task Manager (because it's only in bursts). Additionally the 3D-accelerated Desktop (Aero) is stealing processor cycles (compared to WinXP (I`ve disabled it) and also the system recovery isn't needed in any case. The 64-Bit version should be faster anyway - I suggest you stick with the 64-Bit version and move the directory to a place where windows doesn't use 'extra protection measures' ... PS: For some reason I can't format my posting ...

Last fiddled with by joblack on 2009-11-06 at 20:42
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Old 2009-11-06, 20:56   #5
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I think we're in general agreement, Joe.

This is a clean install and I've got very little running and I reran my tests, so unless that hidden background task showed up at just the right times again (let's say it hates the 32 bit client), then I think there's something strangely wrong with Win7/64's handling of 32bit prime95.

And, yeah, I'm finding out that Vista started a trend to treat some folders/directories as special and to do strange things to their contents. Program Files seems to be one of them. Documents and Setting is another, etc. So, I think I'll just avoid all that magic and keep these files to myself. I think that'll save me from having to run the app as administrator, too--which is probably safer just in case someone finds a way to compromise prime95.

As for Aero, well, I'd like to have it off, but I also run F@H on my GPU and it does something horrible to make the UI lag unless you're running Aero. So, I'm sorta forced to do that. *sigh* It's all a compromise. The trick is to find the best compromise. Hey, maybe I'll find something in Aero that I like? ;)

Thanks again!
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Old 2009-11-06, 22:58   #6
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Quote:
Originally Posted by willmore View Post
I think we're in general agreement, Joe.

This is a clean install and I've got very little running and I reran my tests, so unless that hidden background task showed up at just the right times again (let's say it hates the 32 bit client), then I think there's something strangely wrong with Win7/64's handling of 32bit prime95.

And, yeah, I'm finding out that Vista started a trend to treat some folders/directories as special and to do strange things to their contents. Program Files seems to be one of them. Documents and Setting is another, etc. So, I think I'll just avoid all that magic and keep these files to myself. I think that'll save me from having to run the app as administrator, too--which is probably safer just in case someone finds a way to compromise prime95.

As for Aero, well, I'd like to have it off, but I also run F@H on my GPU and it does something horrible to make the UI lag unless you're running Aero. So, I'm sorta forced to do that. *sigh* It's all a compromise. The trick is to find the best compromise. Hey, maybe I'll find something in Aero that I like? ;)

Thanks again!
If you run F@H that could be the problem. F@H also takes some CPU cycles and it could behaviour differently on WinX and Win7 ... take your measures without F@H ...
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Old 2009-11-07, 05:33   #7
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Joe, I did. :)
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