lkml.org 
[lkml]   [2006]   [Feb]   [7]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    From
    SubjectRe: [rfc][patch] sched: remove smpnice
    Date
    On Wednesday 08 February 2006 01:28, Nick Piggin wrote:
    > I'd like to get some comments on removing smpnice for 2.6.16. I don't
    > think the code is quite ready, which is why I asked for Peter's additions
    > to also be merged before I acked it (although it turned out that it still
    > isn't quite ready with his additions either).
    >
    > Basically I have had similar observations to Suresh in that it does not
    > play nicely with the rest of the balancing infrastructure (and raised
    > similar concerns in my review).
    >
    > The samples (group of 4) I got for "maximum recorded imbalance" on a 2x2
    >
    > SMP+HT Xeon are as follows:
    > | Following boot | hackbench 20 | hackbench 40
    >
    > -----------+----------------+---------------------+---------------------
    > 2.6.16-rc2 | 30,37,100,112 | 5600,5530,6020,6090 | 6390,7090,8760,8470
    > +nosmpnice | 3, 2, 4, 2 | 28, 150, 294, 132 | 348, 348, 294, 347
    >
    > Hackbench raw performance is down around 15% with smpnice (but that in
    > itself isn't a huge deal because it is just a benchmark). However, the
    > samples show that the imbalance passed into move_tasks is increased by
    > about a factor of 10-30. I think this would also go some way to
    > explaining latency blips turning up in the balancing code (though I
    > haven't actually measured that).
    >
    > We'll probably have to revert this in the SUSE kernel.
    >
    > The other option for 2.6.16 would be to fast track Peter's stuff, which
    > I could put some time into... but that seems a bit risky at this stage
    > of the game.
    >
    > I'd like to hear any other suggestions though. Patch included to aid
    > discussion at this stage, rather than to encourage any rash decisions.

    I see the demonstrable imbalance but I was wondering if there is there a real
    world benchmark that is currently affected?

    Cheers,
    Con
    -
    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: 2006-02-07 16:00    [W:0.040 / U:0.216 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site