Messages in this thread | | | From | Con Kolivas <> | Subject | Re: [rfc][patch] sched: remove smpnice | Date | Wed, 8 Feb 2006 01:57:06 +1100 |
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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/
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