1. 03 Apr, 2009 4 commits
  2. 28 Mar, 2009 1 commit
    • Pallipadi, Venkatesh's avatar
      ACPI: cap off P-state transition latency from buggy BIOSes · a59d1637
      Pallipadi, Venkatesh authored
      
      
      Some BIOSes report very high frequency transition latency which are plainly
      wrong on CPus that can change frequency using native MSR interface.
      
      One such system is IBM T42 (2327-8ZU) as reported by Owen Taylor and
      Rik van Riel.
      
      cpufreq_ondemand driver uses this transition latency to come up with a
      reasonable sampling interval to sample CPU usage and with such high
      latency value, ondemand sampling interval ends up being very high
      (0.5 sec, in this particular case), resulting in performance impact due to
      slow response to increasing frequency.
      
      Fix it by capping-off the transition latency to 20uS for native MSR based
      frequency transitions.
      
      mjg: We've confirmed that this also helps on the X31
      Signed-off-by: default avatarVenkatesh Pallipadi <venkatesh.pallipadi@intel.com>
      Acked-by: default avatarMatthew Garrett <mjg@redhat.com>
      Signed-off-by: default avatarLen Brown <len.brown@intel.com>
      a59d1637
  3. 23 Mar, 2009 11 commits
  4. 22 Mar, 2009 6 commits
  5. 21 Mar, 2009 2 commits
  6. 20 Mar, 2009 5 commits
  7. 19 Mar, 2009 11 commits