1. 15 Jun, 2009 1 commit
    • Thomas Renninger's avatar
      [CPUFREQ] ondemand: Uncouple minimal sampling rate from HZ in NO_HZ case · cef9615a
      Thomas Renninger authored
      With this patch you have following minimal sampling rate restrictions:
      
      Kernel restrictions:
      If CONFIG_NO_HZ is set, the limit is 10ms fixed.
      If CONFIG_NO_HZ is not set or no_hz=off boot parameter is used, the
      limits depend on the CONFIG_HZ option:
      HZ=1000: min=20000us  (20ms)
      HZ=250:  min=80000us  (80ms)
      HZ=100:  min=200000us (200ms)
      
      HW restrictions:
      Do not sample/poll more often than HW latency * 100  exported by the low
      level cpufreq HW driver
      
      The higher value of above restrictions is the minimal sampling rate
      that can be set (and can be seen via ondemand/sampling_rate_min sysfs file)
      
      Default sampling rate still is HW latency * 1000, but this will now end
      up in lower values on latest (Intel and AMD) hardware as these can switch
      really fast and sampling rate mostly was limited to the 80ms or 200ms
      (depending on whether HZ=250 or HZ=1000 is used).
      Signed-off-by: default avatarThomas Renninger <trenn@suse.de>
      Cc: Pallipadi Venkatesh <venkatesh.pallipadi@intel.com>
      Signed-off-by: default avatarDave Jones <davej@redhat.com>
      cef9615a
  2. 14 Jun, 2009 32 commits
  3. 13 Jun, 2009 7 commits