1. 06 11月, 2008 1 次提交
    • I
      sched: re-tune balancing · 9fcd18c9
      Ingo Molnar 提交于
      Impact: improve wakeup affinity on NUMA systems, tweak SMP systems
      
      Given the fixes+tweaks to the wakeup-buddy code, re-tweak the domain
      balancing defaults on NUMA and SMP systems.
      
      Turn on SD_WAKE_AFFINE which was off on x86 NUMA - there's no reason
      why we would not want to have wakeup affinity across nodes as well.
      (we already do this in the standard NUMA template.)
      
      lat_ctx on a NUMA box is particularly happy about this change:
      
      before:
      
       |   phoenix:~/l> ./lat_ctx -s 0 2
       |   "size=0k ovr=2.60
       |   2 5.70
      
      after:
      
       |   phoenix:~/l> ./lat_ctx -s 0 2
       |   "size=0k ovr=2.65
       |   2 2.07
      
      a 2.75x speedup.
      
      pipe-test is similarly happy about it too:
      
       |  phoenix:~/sched-tests> ./pipe-test
       |   18.26 usecs/loop.
       |   14.70 usecs/loop.
       |   14.38 usecs/loop.
       |   10.55 usecs/loop.              # +WAKE_AFFINE on domain0+domain1
       |   8.63 usecs/loop.
       |   8.59 usecs/loop.
       |   9.03 usecs/loop.
       |   8.94 usecs/loop.
       |   8.96 usecs/loop.
       |   8.63 usecs/loop.
      
      Also:
      
       - disable SD_BALANCE_NEWIDLE on NUMA and SMP domains (keep it for siblings)
       - enable SD_WAKE_BALANCE on SMP domains
      
      Sysbench+postgresql improves all around the board, quite significantly:
      
                 .28-rc3-11474e2c  .28-rc3-11474e2c-tune
      -------------------------------------------------
          1:             571              688    +17.08%
          2:            1236             1206    -2.55%
          4:            2381             2642    +9.89%
          8:            4958             5164    +3.99%
         16:            9580             9574    -0.07%
         32:            7128             8118    +12.20%
         64:            7342             8266    +11.18%
        128:            7342             8064    +8.95%
        256:            7519             7884    +4.62%
        512:            7350             7731    +4.93%
      -------------------------------------------------
        SUM:           55412            59341    +6.62%
      
      So it's a win both for the runup portion, the peak area and the tail.
      Signed-off-by: NIngo Molnar <mingo@elte.hu>
      9fcd18c9
  2. 05 11月, 2008 7 次提交
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