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drm/i915/perf: better pipeline aged/aging tail updates 

This updates the tail pointer race workaround handling to updating the
'aged' pointer before looking to start aging a new one. There's the
possibility that there is already new data available and so we can
immediately start aging a new pointer without having to first wait for a
later hrtimer callback (and then another to age).

Signed-off-by: Robert Bragg <robert@sixbynine.org>
Reviewed-by: Matthew Auld <matthew.auld@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170511154345.962-8-lionel.g.landwerlin@intel.com
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
This commit is contained in:
Robert Bragg 2017-05-11 16:43:30 +01:00 committed by Chris Wilson
parent 52c57c263f
commit 4117ebc74c
1 changed files with 23 additions and 18 deletions
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41
drivers/gpu/drm/i915/i915_perf.c
View File

@ -391,6 +391,29 @@ static bool gen7_oa_buffer_check_unlocked(struct drm_i915_private *dev_priv)
now = ktime_get_mono_fast_ns();
/* Update the aged tail
*
* Flip the tail pointer available for read()s once the aging tail is
* old enough to trust that the corresponding data will be visible to
* the CPU...
*
* Do this before updating the aging pointer in case we may be able to
* immediately start aging a new pointer too (if new data has become
* available) without needing to wait for a later hrtimer callback.
*/
if (aging_tail != INVALID_TAIL_PTR &&
((now - dev_priv->perf.oa.oa_buffer.aging_timestamp) >
OA_TAIL_MARGIN_NSEC)) {
aged_idx ^= 1;
dev_priv->perf.oa.oa_buffer.aged_tail_idx = aged_idx;
aged_tail = aging_tail;
/* Mark that we need a new pointer to start aging... */
dev_priv->perf.oa.oa_buffer.tails[!aged_idx].offset = INVALID_TAIL_PTR;
aging_tail = INVALID_TAIL_PTR;
}
/* Update the aging tail
*
* We throttle aging tail updates until we have a new tail that
@ -420,24 +443,6 @@ static bool gen7_oa_buffer_check_unlocked(struct drm_i915_private *dev_priv)
}
}
/* Update the aged tail
*
* Flip the tail pointer available for read()s once the aging tail is
* old enough to trust that the corresponding data will be visible to
* the CPU...
*/
if (aging_tail != INVALID_TAIL_PTR &&
((now - dev_priv->perf.oa.oa_buffer.aging_timestamp) >
OA_TAIL_MARGIN_NSEC)) {
aged_idx ^= 1;
dev_priv->perf.oa.oa_buffer.aged_tail_idx = aged_idx;
aged_tail = aging_tail;
/* Mark that we need a new pointer to start aging... */
dev_priv->perf.oa.oa_buffer.tails[!aged_idx].offset = INVALID_TAIL_PTR;
}
spin_unlock_irqrestore(&dev_priv->perf.oa.oa_buffer.ptr_lock, flags);
return aged_tail == INVALID_TAIL_PTR ?