lkml.org 
[lkml]   [2009]   [Apr]   [29]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    SubjectRe: Mainline kernel OLTP performance update
    From
    Date
    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




    \
     
     \ /
      Last update: 2009-04-29 19:51    [from the cache]
    ©2003-2014 Jasper Spaans. hosted at Digital Ocean