1. 30 Oct, 2014 21 commits
  2. 15 Oct, 2014 17 commits
  3. 09 Oct, 2014 2 commits
    • Greg Kroah-Hartman's avatar
      Linux 3.10.57 · f41c15f2
      Greg Kroah-Hartman authored
      f41c15f2
    • Stratos Karafotis's avatar
      cpufreq: ondemand: Change the calculation of target frequency · bed53965
      Stratos Karafotis authored
      commit dfa5bb62 upstream.
      
      The ondemand governor calculates load in terms of frequency and
      increases it only if load_freq is greater than up_threshold
      multiplied by the current or average frequency.  This appears to
      produce oscillations of frequency between min and max because,
      for example, a relatively small load can easily saturate minimum
      frequency and lead the CPU to the max.  Then, it will decrease
      back to the min due to small load_freq.
      
      Change the calculation method of load and target frequency on the
      basis of the following two observations:
      
       - Load computation should not depend on the current or average
         measured frequency.  For example, absolute load of 80% at 100MHz
         is not necessarily equivalent to 8% at 1000MHz in the next
         sampling interval.
      
       - It should be possible to increase the target frequency to any
         value present in the frequency table proportional to the absolute
         load, rather than to the max only, so that:
      
         Target frequency = C * load
      
         where we take C = policy->cpuinfo.max_freq / 100.
      
      Tested on Intel i7-3770 CPU @ 3.40GHz and on Quad core 1500MHz Krait.
      Phoronix benchmark of Linux Kernel Compilation 3.1 test shows an
      increase ~1.5% in performance. cpufreq_stats (time_in_state) shows
      that middle frequencies are used more, with this patch.  Highest
      and lowest frequencies were used less by ~9%.
      
      [rjw: We have run multiple other tests on kernels with this
       change applied and in the vast majority of cases it turns out
       that the resulting performance improvement also leads to reduced
       consumption of energy.  The change is additionally justified by
       the overall simplification of the code in question.]
      Signed-off-by: default avatarStratos Karafotis <stratosk@semaphore.gr>
      Acked-by: default avatarViresh Kumar <viresh.kumar@linaro.org>
      Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
      Cc: Mark Brown <broonie@kernel.org>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      bed53965