1. 30 May, 2016 1 commit
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  7. 02 May, 2016 1 commit
  8. 28 Apr, 2016 10 commits
  9. 27 Apr, 2016 2 commits
    • Srinivas Pandruvada's avatar
      cpufreq: intel_pstate: Enable PPC enforcement for servers · 2b3ec765
      Srinivas Pandruvada authored
      For platforms which are controlled via remove node manager, enable _PPC by
      default. These platforms are mostly categorized as enterprise server or
      performance servers. These platforms needs to go through some
      certifications tests, which tests control via _PPC.
      The relative risk of enabling by default is  low as this is is less likely
      that these systems have broken _PSS table.
      Signed-off-by: default avatarSrinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
      Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
      2b3ec765
    • Srinivas Pandruvada's avatar
      cpufreq: intel_pstate: Adjust policy->max · 3be9200d
      Srinivas Pandruvada authored
      When policy->max is changed via _PPC or sysfs and is more than the max non
      turbo frequency, it does not really change resulting performance in some
      processors. When policy->max results in a P-State ratio more than the
      turbo activation ratio, then processor can choose any P-State up to max
      turbo. So the user or _PPC setting has no value, but this can cause
      undesirable side effects like:
      - Showing reduced max percentage in Intel P-State sysfs
      - It can cause reduced max performance under certain boundary conditions:
      The requested max scaling frequency either via _PPC or via cpufreq-sysfs,
      will be converted into a fixed floating point max percent scale. In
      majority of the cases this will result in correct max. But not 100% of the
      time. If the _PPC is requested at a point where the calculation lead to a
      lower max, this can result in a lower P-State then expected and it will
      impact performance.
      Example of this condition using a Broadwell laptop with config TDP.
      
      ACPI _PSS table from a Broadwell laptop
      2301000 2300000 2200000 2000000 1900000 1800000 1700000 1500000 1400000
      1300000 1100000 1000000 900000 800000 600000 500000
      
      The actual results by disabling config TDP so that we can get what is
      requested on or below 2300000Khz.
      
      scaling_max_freq        Max Requested P-State   Resultant scaling
      max
      ---------------------------------------- ----------------------
      2400000                 18                      2900000 (max
      turbo)
      2300000                 17                      2300000 (max
      physical non turbo)
      2200000                 15                      2100000
      2100000                 15                      2100000
      2000000                 13                      1900000
      1900000                 13                      1900000
      1800000                 12                      1800000
      1700000                 11                      1700000
      1600000                 10                      1600000
      1500000                 f                       1500000
      1400000                 e                       1400000
      1300000                 d                       1300000
      1200000                 c                       1200000
      1100000                 a                       1000000
      1000000                 a                       1000000
      900000                  9                        900000
      800000                  8                        800000
      700000                  7                        700000
      600000                  6                        600000
      500000                  5                        500000
      ------------------------------------------------------------------
      
      Now set the config TDP level 1 ratio as 0x0b (equivalent to 1100000KHz)
      in BIOS (not every system will let you adjust this).
      The turbo activation ratio will be set to one less than that, which will
      be 0x0a (So any request above 1000000KHz should result in turbo region
      assuming no thermal limits).
      Here _PPC will request max to 1100000KHz (which basically should still
      result in turbo as this is more than the turbo activation ratio up to
      max allowable turbo frequency), but actual calculation resulted in a max
      ceiling P-State which is 0x0a. So under any load condition, this driver
      will not request turbo P-States. This will be a huge performance hit.
      
      When config TDP feature is ON, if the _PPC points to a frequency above
      turbo activation ratio, the performance can still reach max turbo. In this
      case we don't need to treat this as the reduced frequency in set_policy
      callback.
      
      In this change when config TDP is active (by checking if the physical max
      non turbo ratio is more than the current max non turbo ratio), any request
      above current max non turbo is treated as full performance.
      Signed-off-by: default avatarSrinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
      [ rjw : Minor cleanups ]
      Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
      3be9200d