1. 11 11月, 2008 15 次提交
  2. 10 11月, 2008 13 次提交
  3. 09 11月, 2008 11 次提交
  4. 08 11月, 2008 1 次提交
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      sched: improve sched_clock() performance · 0d12cdd5
      Ingo Molnar 提交于
      in scheduler-intense workloads native_read_tsc() overhead accounts for
      20% of the system overhead:
      
       659567 system_call                              41222.9375
       686796 schedule                                 435.7843
       718382 __switch_to                              665.1685
       823875 switch_mm                                4526.7857
       1883122 native_read_tsc                          55385.9412
       9761990 total                                      2.8468
      
      this is large part due to the rdtsc_barrier() that is done before
      and after reading the TSC.
      
      But sched_clock() is not a precise clock in the GTOD sense, using such
      barriers is completely pointless. So remove the barriers and only use
      them in vget_cycles().
      
      This improves lat_ctx performance by about 5%.
      Signed-off-by: NIngo Molnar <mingo@elte.hu>
      0d12cdd5