[Bug 107410] [SKL] Up to 20% performance regression in GpuTest Triangle, due to 2x higher CPU power usage

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=107410

Chris Wilson <chris at chris-wilson.co.uk> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         Resolution|---                         |FIXED
             Status|NEW                         |RESOLVED

--- Comment #12 from Chris Wilson <chris at chris-wilson.co.uk> ---
commit 01e61a42a5d345a4c0205889498f0c9a0fb9ee8c
Author: Srinivas Pandruvada <srinivas.pandruvada at linux.intel.com>
Date:   Mon Jul 30 15:00:29 2018 -0700

    cpufreq: intel_pstate: Limit the scope of HWP dynamic boost platforms

    Dynamic boosting of HWP performance on IO wake showed significant
    improvement to IO workloads. This series was intended for Skylake Xeon
    platforms only and feature was enabled by default based on CPU model
    number.

    But some Xeon platforms reused the Skylake desktop CPU model number. This
    caused some undesirable side effects to some graphics workloads. Since
    they are heavily IO bound, the increase in CPU performance decreased the
    power available for GPU to do its computing and hence decrease in graphics
    benchmark performance.

    For example on a Skylake desktop, GpuTest benchmark showed average FPS
    reduction from 529 to 506.

    This change makes sure that HWP boost feature is only enabled for Skylake
    server platforms by using ACPI FADT preferred PM Profile. If some desktop
    users wants to get benefit of boost, they can still enable boost from
    intel_pstate sysfs attribute "hwp_dynamic_boost".

    Fixes: 41ab43c9c89e (cpufreq: intel_pstate: enable boost for Skylake Xeon)
    Link: https://bugs.freedesktop.org/show_bug.cgi?id=107410
    Reported-by: Eero Tamminen <eero.t.tamminen at intel.com>
    Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada at linux.intel.com>
    Reviewed-by: Francisco Jerez <currojerez at riseup.net>
    Acked-by: Mel Gorman <mgorman at techsingularity.net>
    Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki at intel.com>

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