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Date: Sun, 20 Sep 2009 16:03:23 -0500 From: "Langsdorf, Mark" <mark.langsdorf@....com> To: "'Avi Kivity'" <avi@...hat.com>, Peter Zijlstra <a.p.zijlstra@...llo.nl> CC: Ingo Molnar <mingo@...e.hu>, Mike Galbraith <efault@....de>, "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org> Subject: RE: [PATCH] Prevent immediate process rescheduling > > Really hate this change though,. doesn't seem right to not > pick the same > > task again if its runnable. Bad for cache footprint. > > I agree, yielding should be explicitly requested. > > Also, on a heavily overcommitted box an undirected yield might take > quite a long time to find the thread that's holding the lock. > I think a > yield_to() will be a lot better: > > - we can pick one of the vcpus belonging to the same guest to improve > the probability that the lock actually get released Is there a way to find the other vcpus belonging to the same guest? I poked around at that, but couldn't find one. > - we avoid an issue when the other vcpus are on different > runqueues (in which case the current patch does nothing) > - we can fix the accounting by donating vruntime from current to the > yielded-to vcpu I may need someone to walk me through the vruntime donation but that's secondary to finding the other vcpus. -Mark Langsdorf Operating System Research Center AMD -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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