1. 16 Oct, 2015 2 commits
    • Prarit Bhargava's avatar
      cpufreq: intel_pstate: Fix intel_pstate powersave min_perf_pct value · 51443fbf
      Prarit Bhargava authored
      On systems that initialize the intel_pstate driver with the performance
      governor, and then switch to the powersave governor will not transition to
      lower cpu frequencies until /sys/devices/system/cpu/intel_pstate/min_perf_pct
      is set to a low value.
      
      The behavior of governor switching changed after commit a0475992
      ("[cpufreq] intel_pstate: honor user space min_perf_pct override on
       resume").  The commit introduced tracking of performance percentage
      changes via sysfs in order to restore userspace changes during
      suspend/resume.  The problem occurs because the global values of the newly
      introduced max_sysfs_pct and min_sysfs_pct are not lowered on the governor
      change and this causes the powersave governor to inherit the performance
      governor's settings.
      
      A simple change would have been to reset max_sysfs_pct to 100 and
      min_sysfs_pct to 0 on a governor change, which fixes the problem with
      governor switching.  However, since we cannot break userspace[1] the fix
      is now to give each governor its own limits storage area so that governor
      specific changes are tracked.
      
      I successfully tested this by booting with both the performance governor
      and the powersave governor by default, and switching between the two
      governors (while monitoring /sys/devices/system/cpu/intel_pstate/ values,
      and looking at the output of cpupower frequency-info).  Suspend/Resume
      testing was performed by Doug Smythies.
      
      [1] Systems which suspend/resume using the unmaintained pm-utils package
      will always transition to the performance governor before the suspend and
      after the resume.  This means a system using the powersave governor will
      go from powersave to performance, then suspend/resume, performance to
      powersave.  The simple change during governor changes would have been
      overwritten when the governor changed before and after the suspend/resume.
      I have submitted https://bugzilla.redhat.com/show_bug.cgi?id=1271225
      against Fedora to remove the 94cpufreq file that causes the problem.  It
      should be noted that pm-utils is obsoleted with newer versions of systemd.
      Signed-off-by: default avatarPrarit Bhargava <prarit@redhat.com>
      Acked-by: default avatarKristen Carlson Accardi <kristen@linux.intel.com>
      Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
      51443fbf
    • Rafael J. Wysocki's avatar
      7855e102
  2. 15 Oct, 2015 1 commit
  3. 14 Oct, 2015 6 commits
  4. 12 Oct, 2015 1 commit
  5. 11 Oct, 2015 8 commits
  6. 10 Oct, 2015 12 commits
  7. 09 Oct, 2015 10 commits