Core i7 Very slow folding

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Core i7 Very slow folding

Postby jimbo90210us » Tue Mar 16, 2010 6:44 am

I have started folding again after a long time off. Recently I bought a Core i7 930 which I thought I would give a go on Linux. The problem is it is running very slow about a 1000 steps for 15 minutes of folding on a 6024.

Current setup is
Core i7 930 @ 2.8GHz
6Gb 1600 MHz RAM
Ubuntu 9.10 kernel 2.6.31-20
FAH6.29

I have tried with the flags -advmethods - smp 8: very slow, in the system monitor 7 cores at 100% and 1 at 5 - 15%
also -advmethods -smp 7 which is about 4 - 4:30 per step which seems about right.

I think the smp client waits for the slowest core which would be the idling one which would cause it to go slow.

Why so slow for the 8th core?
Is this a problem with my install or my CPU?
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Re: Core i7 Very slow folding

Postby bruce » Tue Mar 16, 2010 6:54 am

Project 6024 uses the new FahCore_a3. It does something more or less like waiting for the slowest core. When you have other things running on the same computer, the 8 threads which normally need pretty much the same amounts of time get unbalanced and the process slows way down. The developers are aware of this problem and have been working to improve the sitation so it's not as bad as it once was, but it still needs improving.

On computers that run other processes, (assuming your OS is seeing 8 CPUs) it' often beneficial to configure FAH with the setting -smp 7, leaving on free CPU to soak up the various interruptions. Hopefully this will be fixed soon and this technique will no longer be needed.
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Re: Core i7 Very slow folding

Postby toTOW » Tue Mar 16, 2010 10:43 am

I've noticed the same issue on my i7 under Ubuntu 9.10 ...

The solution is to force cpufreq governor into performance mode instead of on demand mode.
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Re: Core i7 Very slow folding

Postby jimbo90210us » Wed Mar 17, 2010 6:45 pm

Thanks for the advice. I am now folding on the core i7 with -smp 7 and it is going reasonably quickly.

What's really annoying is the fact that because I installed a few different versions of Ubuntu and started folding using my username each time it looks like I have now lost my performance bonuses on all work units. This does make me question what the point is of folding on any future boxes that I start up. If I experienced the same issues I would have to fold for a good while to get the bonuses back again and to be perfectly honest it's not worth it.
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Re: Core i7 Very slow folding

Postby bruce » Wed Mar 17, 2010 6:59 pm

If you've used the same passkey and the same UserName on all your installations, then there should be no problem with the bonuses. Stanford did have a 24-hour glitch in their bonus program and that's probably what you're seeing.

viewtopic.php?f=58&t=13847
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Re: Core i7 Very slow folding

Postby jimbo90210us » Wed Mar 17, 2010 7:00 pm

Ah didn't realise that maybe I am adding 2 and 2 and getting 6. Oooops
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