]> git.baikalelectronics.ru Git - kernel.git/commit
drm/i915/perf: avoid poll, read, EAGAIN busy loops
authorRobert Bragg <robert@sixbynine.org>
Thu, 11 May 2017 15:43:25 +0000 (16:43 +0100)
committerChris Wilson <chris@chris-wilson.co.uk>
Sat, 13 May 2017 09:59:07 +0000 (10:59 +0100)
commite450f142e1b558158d9e689f8cdb8279155da144
treebec5aacb0804270f94a47bd28125ca9173da0d94
parentdeac995d21ed8fe4ab858414a9165a59224e02c2
drm/i915/perf: avoid poll, read, EAGAIN busy loops

If the function for checking whether there is OA buffer data available
(during a poll or blocking read) has false positives then we want to
avoid a situation where the subsequent read() returns EAGAIN (after
a more accurate check) followed by a poll() immediately reporting
the same false positive POLLIN event and effectively maintaining a
busy loop until there really is data.

This makes sure that we clear the .pollin event status whenever we
return EAGAIN to userspace which will throttle subsequent POLLIN events
and repeated attempts to read to the 5ms intervals of the hrtimer
callback we have.

Signed-off-by: Robert Bragg <robert@sixbynine.org>
Reviewed-by: Matthew Auld <matthew.auld@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170511154345.962-3-lionel.g.landwerlin@intel.com
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
drivers/gpu/drm/i915/i915_perf.c