[Bug 71029] [ilk] igt/gem_close_race is slow due to mutex contention vs clflush

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=71029

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

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

--- Comment #21 from Chris Wilson <chris at chris-wilson.co.uk> ---
commit 98165d60bec04d258eeb9623550e58a8bc2f3906
Author: Chris Wilson <chris at chris-wilson.co.uk>
Date:   Fri Jul 11 23:36:15 2014 +0100

    igt/gem_close_race: Trim object size

    The challenge here is to race GPU activity versus the gem_close. Using a
    large objects makes the window of GPU activity larger - except on !llc
    systems we then incur massive overhead from clflush, likely destroying
    any race (due to mutex contention). And that mutex contention is
    amplified by the number of cores - bad news for Baytrail.

    Give up and make the objects smaller and hope that the test is run
    frequently enough to catch the race.

    References: https://bugs.freedesktop.org/show_bug.cgi?id=71029
    Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>

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