From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jeremy Fitzhardinge Subject: Re: Stolen and degraded time and schedulers Date: Wed, 14 Mar 2007 08:08:17 -0700 Message-ID: <45F80FE1.3030603@goop.org> References: <45F6D1D0.6080905@goop.org> <1173816769.22180.14.camel@localhost> <45F70A71.9090205@goop.org> <1173821224.1416.24.camel@dwalker1> <45F71EA5.2090203@goop.org> <45F74515.7010808@vmware.com> <45F77C27.8090604@goop.org> <20070314135845.GG22466@csclub.uwaterloo.ca> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20070314135845.GG22466@csclub.uwaterloo.ca> Sender: linux-kernel-owner@vger.kernel.org To: Lennart Sorensen Cc: Dan Hecht , dwalker@mvista.com, cpufreq@lists.linux.org.uk, Linux Kernel Mailing List , Con Kolivas , Chris Wright , Virtualization Mailing List , john stultz , Ingo Molnar , Thomas Gleixner List-Id: virtualization@lists.linuxfoundation.org Lennart Sorensen wrote: > How would you deal with something like a pentium 4 HT processor where > you may run slower just because you got scheduled on the sibling of a > cpu that happens to run something else needing the same execution units > you do, causing you to get delayed more, even though the cpu is running > full speed and nothing else is trying to use your "cpu"? I don't think > there is any way to know what the real impact of two processes on a HT > cpu have on each other. > > Interesting goal. Not sure it can be done. You're right. That's a very tough case. I don't know if there's any way to do a reasonable estimate of the slowdown. You could handwave it and say "if both threads are running a process, then apply an X scaling factor to their rate of progress". That might be enough. J