Messages in this thread | | | Subject | Re: Mainline kernel OLTP performance update | From | Chris Mason <> | Date | Wed, 29 Apr 2009 13:46:36 -0400 |
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On Wed, 2009-04-29 at 18:25 +0200, Peter Zijlstra wrote: > On Wed, 2009-04-29 at 09:07 -0700, Andrew Morton wrote: > > On Wed, 29 Apr 2009 08:48:19 -0700 "Styner, Douglas W" <douglas.w.styner@intel.com> wrote: > > > > > >-----Original Message----- > > > >From: Andrew Morton [mailto:akpm@linux-foundation.org] > > > >Sent: Wednesday, April 29, 2009 12:30 AM > > > >To: Styner, Douglas W > > > >Cc: linux-kernel@vger.kernel.org; Tripathi, Sharad C; > > > >arjan@linux.intel.com; Wilcox, Matthew R; Kleen, Andi; Siddha, Suresh B; > > > >Ma, Chinang; Wang, Peter Xihong; Nueckel, Hubert; Recalde, Luis F; Nelson, > > > >Doug; Cheng, Wu-sun; Prickett, Terry O; Shunmuganathan, Rajalakshmi; Garg, > > > >Anil K; Chilukuri, Harita; chris.mason@oracle.com > > > >Subject: Re: Mainline kernel OLTP performance update > > > > > > > >On Tue, 28 Apr 2009 10:08:22 -0700 "Styner, Douglas W" > > > ><douglas.w.styner@intel.com> wrote: > > > > > > > >> Summary: Measured the mainline kernel from kernel.org (2.6.30-rc3). > > > >> > > > >> The regression for 2.6.30-rc3 against the baseline, 2.6.24.2 is 1.91%. > > > >Oprofile reports 71.1626% user, 28.8295% system. > > > >> > > > >> Linux OLTP Performance summary > > > >> Kernel# Speedup(x) Intr/s CtxSw/s us% sys% idle% > > > >iowait% > > > >> 2.6.24.2 1.000 22106 43709 75 24 0 0 > > > >> 2.6.30-rc3 0.981 30645 43027 75 25 0 0 > > > > > > > >The main difference there is the interrupt frequency. Do we know which > > > >interrupt source(s) caused this? > > > > > > Our analysis of the interrupts shows that rescheduling interrupts are > > > up 2.2x from 2.6.24.2 --> 2.6.30-rc3. Qla2xxx interrupts are roughly > > > the same. > > > > (top-posting repaired) > > > > OK, thanks. Seems odd that the rescheduling interrupt rate increased > > while the context-switch rate actually fell a couple of percent. > > > > This came up a few weeks ago and iirc Peter was mainly involved, and I > > don't believe that anything conclusive ended up happening. Peter, > > could you please remind us of (and summarise) the story here? > > I've had several reports about the resched-ipi going in overdrive, but > nobody bothered to bisect it, nor have I yet done so -- no clear ideas > on why it is doing so. > > I'll put it somewhere higher on the todo list. >
One cause of them in the past was the ondemand cpufreq module. It got fixed up for my laptop workload at least starting w/2.6.29, but it might make sense to try without ondemand if you're running it.
-chris
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