I have a plan to write a quick test to exercise concurrent usage of
i915_gem_shrink(), the simplest way looks to be to have multiple threads
using debugfs/i915_drop_caches. However, we currently take one lock over
the entire function, serialising the calls into i915_gem_shrink() so
reduce the lock coverage.
Testcase: igt/gem_shrink/reclaim
Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
Cc: Joonas Lahtinen <joonas.lahtinen@xxxxxxxxxxxxxxx>
---
drivers/gpu/drm/i915/i915_debugfs.c | 31 +++++++++++++++----------------
1 file changed, 15 insertions(+), 16 deletions(-)
diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c
index 25b97788b906..bd16db60164c 100644
--- a/drivers/gpu/drm/i915/i915_debugfs.c
+++ b/drivers/gpu/drm/i915/i915_debugfs.c
@@ -4116,26 +4116,28 @@ i915_drop_caches_set(void *data, u64 val)
{
struct drm_i915_private *dev_priv = data;
struct drm_device *dev = &dev_priv->drm;
- int ret;
+ int ret = 0;
DRM_DEBUG("Dropping caches: 0x%08llx\n", val);
/* No need to check and wait for gpu resets, only libdrm auto-restarts
* on ioctls on -EAGAIN. */
- ret = mutex_lock_interruptible(&dev->struct_mutex);
- if (ret)
- return ret;
-
- if (val & DROP_ACTIVE) {
- ret = i915_gem_wait_for_idle(dev_priv,
- I915_WAIT_INTERRUPTIBLE |
- I915_WAIT_LOCKED);
+ if (val & (DROP_ACTIVE | DROP_RETIRE)) {
+ ret = mutex_lock_interruptible(&dev->struct_mutex);
if (ret)
- goto unlock;
- }
+ return ret;
- if (val & DROP_RETIRE)
- i915_gem_retire_requests(dev_priv);
+ if (val & DROP_ACTIVE) {
+ ret = i915_gem_wait_for_idle(dev_priv,
+ I915_WAIT_INTERRUPTIBLE |
+ I915_WAIT_LOCKED);
+ }
+
+ if (val & DROP_RETIRE)
+ i915_gem_retire_requests(dev_priv);
+
+ mutex_unlock(&dev->struct_mutex);
+ }
lockdep_set_current_reclaim_state(GFP_KERNEL);
if (val & DROP_BOUND)
@@ -4148,9 +4150,6 @@ i915_drop_caches_set(void *data, u64 val)
i915_gem_shrink_all(dev_priv);
lockdep_clear_current_reclaim_state();
-unlock:
- mutex_unlock(&dev->struct_mutex);
-
if (val & DROP_FREED) {
synchronize_rcu();
i915_gem_drain_freed_objects(dev_priv);
--
2.11.0
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