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authorNick Piggin <npiggin@suse.de>2006-02-10 01:51:02 -0800
committerLinus Torvalds <torvalds@g5.osdl.org>2006-02-10 08:13:11 -0800
commita2000572ad511f5f43091ed7bd2cc3b913104a1e (patch)
tree56279392dece8e11c33d3754854551aa6773095b /drivers
parent4b0955a6edb9b058ca1314ca210a92ee166c4d9a (diff)
[PATCH] sched: remove smpnice
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. Cc: "Siddha, Suresh B" <suresh.b.siddha@intel.com> Acked-by: Ingo Molnar <mingo@elte.hu> Cc: Peter Williams <pwil3058@bigpond.net.au> Cc: "Martin J. Bligh" <mbligh@aracnet.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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