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Message-ID: <1325717396.3084.12.camel@laptop> Date: Wed, 04 Jan 2012 23:49:56 +0100 From: Peter Zijlstra <peterz@...radead.org> To: Stephane Eranian <eranian@...gle.com> Cc: linux-kernel@...r.kernel.org, mingo@...e.hu, gleb@...hat.com, asharma@...com, vince@...ter.net, wcohen@...hat.com Subject: Re: perf_events: proposed fix for broken intr throttling (repost) On Wed, 2012-01-04 at 21:33 +0000, Stephane Eranian wrote: > > I don't think it needs that, I do dislike the unconditional iterate all > > events thing though. Maybe we can set some per-cpu state indicating > > someone got throttled (rare under normal operation -- you'd hope) and > > only iterate to unthrottle when we find this set. > > > Could try that too. > > > I think the event scheduling resulting from migration will already > > re-enable the event, avoiding the loss of unthrottle due to that.. > > although it would be good to verify that. > > > Yes, you're not dead forever, but still it is not acceptable as is. Oh for sure, I didn't mean it like that. What I was getting at is a counter getting throttled on one cpu, setting the per-cpu variable, getting migrated and not getting unthrottled due to now living on another cpu which doesn't have the per-cpu thing set. If the scheduling resulting from the migration already unthrottles that scenario can't happen. -- 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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