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Date: | Fri, 13 Aug 2010 18:05:40 -0700 |
From: | Tim Prince <n8tm AT aol DOT com> |
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To: | cygwin AT cygwin DOT com |
Subject: | Re: Cygwin speed difference on multiple cores -vs- single-core? |
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On 8/13/2010 5:37 PM, Andy Nicholas wrote: > Hi Folks, > > When using cygwin, I've noticed that there seems to be a large speed > difference when I boot my windows 7 (32-bit) machine in single-core mode > versus the regular number of cores (4, Core i7-930). > > I've read through the FAQ and didn't notice anything about this issue. > > Normally, I would expect nearly no speed difference based on the Windows > environment... but after some extensive timing tests it seems like the single- > core machine is usually at least 2x faster than using the same machine setup > in multi-core mode. I limit the number of cores using MSCONFIG, advanced boot > options. > > We have some simple script and more complex scripts which show this behavior. > The simple scripts do straightforward things like "rm -rf" over some directory > trees. Even the simple scripts run slowly when the PC is booted with multiple > cores. > > Is this known behavior? Is there some way to work around it so I can boot my > PC, use all the cores with other apps, and continue run cygwin 2x faster? > > Several possibilities which you haven't addressed may affect this. Are you comparing the performance of a single thread when locked to a single core, compared to when it is permitted to rotate among cores, with or without HyperThread enabled? I've never run into anyone running win7 32-bit; it may have more such issues than the more common 64-bit. -- Tim Prince -- Problem reports: http://cygwin.com/problems.html FAQ: http://cygwin.com/faq/ Documentation: http://cygwin.com/docs.html Unsubscribe info: http://cygwin.com/ml/#unsubscribe-simple
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