lkml.org 
[lkml]   [2007]   [Feb]   [27]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    SubjectRe: 2.6.21-rc1: known regressions (v2) (part 2)
    From
    Date
    On Tue, 2007-02-27 at 09:33 +0100, Ingo Molnar wrote:
    > * Michal Piotrowski <michal.k.k.piotrowski@gmail.com> wrote:
    >
    > > Thomas Gleixner napisał(a):
    > > > Adrian,
    > > >
    > > > On Mon, 2007-02-26 at 23:05 +0100, Adrian Bunk wrote:
    > > >> Subject : kernel BUG at kernel/time/tick-sched.c:168 (CONFIG_NO_HZ)
    > > >> References : http://lkml.org/lkml/2007/2/16/346
    > > >> Submitter : Michal Piotrowski <michal.k.k.piotrowski@gmail.com>
    > > >> Handled-By : Thomas Gleixner <tglx@linutronix.de>
    > > >> Status : problem is being debugged
    > > >
    > > > The BUG_ON() was replaced by a warning printk(). The BUG_ON() exposed a
    > > > problem with the SMT scheduler. See below.
    > > >
    > > >> Subject : BUG: soft lockup detected on CPU#0
    > > >> NOHZ: local_softirq_pending 20 (SMT scheduler)
    > > >> References : http://lkml.org/lkml/2007/2/20/257
    > > >> Submitter : Michal Piotrowski <michal.k.k.piotrowski@gmail.com>
    > > >> Handled-By : Thomas Gleixner <tglx@linutronix.de>
    > > >> Ingo Molnar <mingo@elte.hu>
    > > >> Status : problem is being debugged
    > > >
    > > > Patch available, not confirmed yet.
    > > >
    > >
    > > I can confirm that the bug is fixed (over 20 hours of testing should
    > > be enough).
    >
    > thanks alot! I think this thing was a long-term performance/latency
    > regression in HT scheduling as well.

    Agreed.

    I was recently looking at that spot because I found that niced tasks
    were taking latency hits, and disabled it, which helped a bunch. I also
    can't understand why it would be OK to interleave a normal task with an
    RT task sometimes, but not others.. that's meaningless to the RT task.

    IMHO, SMT scheduling should be a buyer beware thing. Maximizing your
    core utilization comes at a price, but so does disabling it, so I think
    letting the user decide what he wants is the right thing to do.

    -Mike

    -
    To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
    the body of a message to majordomo@vger.kernel.org
    More majordomo info at http://vger.kernel.org/majordomo-info.html
    Please read the FAQ at http://www.tux.org/lkml/

    \
     
     \ /
      Last update: 2007-02-27 09:57    [W:0.029 / U:1.752 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site