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Date: Wed, 18 Jun 2014 05:56:14 -0700 From: "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com> To: Andi Kleen <ak@...ux.intel.com> Cc: Dave Hansen <dave.hansen@...el.com>, LKML <linux-kernel@...r.kernel.org>, Josh Triplett <josh@...htriplett.org>, "Chen, Tim C" <tim.c.chen@...el.com>, Christoph Lameter <cl@...ux.com>, peterz@...radead.org Subject: Re: [bisected] pre-3.16 regression on open() scalability On Wed, Jun 18, 2014 at 05:40:28AM -0700, Andi Kleen wrote: > On Tue, Jun 17, 2014 at 09:47:45PM -0700, Paul E. McKenney wrote: > > On Tue, Jun 17, 2014 at 07:27:31PM -0700, Andi Kleen wrote: > > > > OK. What would you suggest instead? If all we do is to revert the > > > > > > Hang checker should have two timer phases: > > > > > > Timer fires first time: > > > - Save context switch counter on that. Force a reschedule to some > > > work queue. Rearm timer > > > > > > Timer fires again: > > > - Check reschedule count. If the reschedule count changed > > > it was a real hang, otherwise ignore. > > > > I could take that approach, but the RT guys aren't going to thank me for > > the wakeup associated with the work queue. I suppose that I could use > > They can disable the hang timer if it's really problem. > > If they cannot tolerate a single context switch they likely > cannot tolerate a timer firing either. Ah, but I make the timer fire on some other CPU. Thanx, Paul -- 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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