On Tue, 2012-09-04 at 11:43 -0700, tip-bot for Peter Zijlstra wrote: > Commit-ID: f319da0c6894fcf55e21320e40506418a2aad629 > Gitweb: http://git.kernel.org/tip/f319da0c6894fcf55e21320e40506418a2aad629 > Author: Peter Zijlstra <peterz@xxxxxxxxxxxxx> > AuthorDate: Mon, 20 Aug 2012 11:26:57 +0200 > Committer: Ingo Molnar <mingo@xxxxxxxxxx> > CommitDate: Tue, 4 Sep 2012 14:30:18 +0200 > > sched: Fix load avg vs cpu-hotplug > > Rabik and Paul reported two different issues related to the same few > lines of code. > > Rabik's issue is that the nr_uninterruptible migration code is wrong in > that he sees artifacts due to this (Rabik please do expand in more > detail). > > Paul's issue is that this code as it stands relies on us using > stop_machine() for unplug, we all would like to remove this assumption > so that eventually we can remove this stop_machine() usage altogether. > > The only reason we'd have to migrate nr_uninterruptible is so that we > could use for_each_online_cpu() loops in favour of > for_each_possible_cpu() loops, however since nr_uninterruptible() is the > only such loop and its using possible lets not bother at all. > > The problem Rabik sees is (probably) caused by the fact that by > migrating nr_uninterruptible we screw rq->calc_load_active for both rqs > involved. > > So don't bother with fancy migration schemes (meaning we now have to > keep using for_each_possible_cpu()) and instead fold any nr_active delta > after we migrate all tasks away to make sure we don't have any skewed > nr_active accounting. Oh argh.. this patch isn't actually right.. I actually removed it from my series but forgot to update the tarball. Ingo can you still make it go away or should I do a delta? -- To unsubscribe from this list: send the line "unsubscribe linux-tip-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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