On 02/05/2019 15:00, Chris Wilson wrote:
Quoting Tvrtko Ursulin (2019-05-02 14:34:11)
On 01/05/2019 12:45, Chris Wilson wrote:
If the user is racing a call to debugfs/i915_drop_caches with ongoing
submission from another thread/process, we may never end up idling the
GPU and be uninterruptibly spinning in debugfs/i915_drop_caches trying
to catch an idle moment.
Just flush the work once, that should be enough to park the system under
correct conditions. Outside of those we either have a driver bug or the
user is racing themselves. Sadly, because the user may be provoking the
unwanted situation we can't put a warn here to attract attention to a
probable bug.
Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
---
drivers/gpu/drm/i915/i915_debugfs.c | 4 +---
1 file changed, 1 insertion(+), 3 deletions(-)
diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c
index 7e8898d0b78b..2ecefacb1e66 100644
--- a/drivers/gpu/drm/i915/i915_debugfs.c
+++ b/drivers/gpu/drm/i915/i915_debugfs.c
@@ -3933,9 +3933,7 @@ i915_drop_caches_set(void *data, u64 val)
fs_reclaim_release(GFP_KERNEL);
if (val & DROP_IDLE) {
- do {
- flush_delayed_work(&i915->gem.retire_work);
- } while (READ_ONCE(i915->gt.awake));
+ flush_delayed_work(&i915->gem.retire_work);
flush_work(&i915->gem.idle_work);
}
What were supposed to be semantics of DROP_IDLE? Now it seems rather
weak. Should it for instance also imply DROP_ACTIVE?
All I need for DROP_IDLE is that the idle worker is flushed. I've always
assumed you would pass in DROP_ACTIVE | DROP_RETIRE | DROP_IDLE as the
trifecta.
The biggest problem here is that's it is an uninterruptible loop.
Okay.. lets see if IGT is playing ball. :)
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx>
Regards,
Tvrtko
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