1. 26 Oct, 2014 1 commit
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  3. 11 Oct, 2014 1 commit
  4. 10 Oct, 2014 1 commit
    • Andreas Schwab's avatar
      cpufreq: Fix wrong time unit conversion · ebeb8843
      Andreas Schwab authored
      The time spent by a CPU under a given frequency is stored in jiffies unit
      in the cpu var cpufreq_stats_table->time_in_state[i], i being the index of
      the frequency.
      
      This is what is displayed in the following file on the right column:
      
           cat /sys/devices/system/cpu/cpuX/cpufreq/stats/time_in_state
           2301000 19835820
           2300000 3172
           [...]
      
      Now cpufreq converts this jiffies unit delta to clock_t before returning it
      to the user as in the above file. And that conversion is achieved using the API
      cputime64_to_clock_t().
      
      Although it accidentally works on traditional tick based cputime accounting, where
      cputime_t maps directly to jiffies, it doesn't work with other types of cputime
      accounting such as CONFIG_VIRT_CPU_ACCOUNTING_* where cputime_t can map to nsecs
      or any granularity preffered by the architecture.
      
      For example we get a buggy zero delta on full dyntick configurations:
      
           cat /sys/devices/system/cpu/cpuX/cpufreq/stats/time_in_state
           2301000 0
           2300000 0
           [...]
      
      Fix this with using the proper jiffies_64_t to clock_t conversion.
      Reported-and-tested-by: default avatarCarsten Emde <C.Emde@osadl.org>
      Signed-off-by: default avatarAndreas Schwab <schwab@linux-m68k.org>
      Signed-off-by: default avatarFrederic Weisbecker <fweisbec@gmail.com>
      Acked-by: default avatarPaul E. McKenney <paulmck@linux.vnet.ibm.com>
      Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
      
      (cherry picked from commit a857c0b9)
      Signed-off-by: default avatarSasha Levin <sasha.levin@oracle.com>
      ebeb8843