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authorChris Wilson <[email protected]>2017-05-17 13:10:05 +0100
committerChris Wilson <[email protected]>2017-05-17 13:38:13 +0100
commit349bdb68bd48f4e1861058ac2dbaa0aafd4ca38d (patch)
tree47313c4d515f04daf17f46cb798cd1a8ba20d53c
parentc5cf9a9147ff6fc9f87251a8f8a5b6ac8b8bdcdc (diff)
drm/i915/execlists: Reduce lock contention between schedule/submit_request
If we do not require to perform priority bumping, and we haven't yet submitted the request, we can update its priority in situ and skip acquiring the engine locks -- thus avoiding any contention between us and submit/execute. v2: Remove the stack element from the list if we can do the early assignment. Signed-off-by: Chris Wilson <[email protected]> Reviewed-by: Tvrtko Ursulin <[email protected]> Link: http://patchwork.freedesktop.org/patch/msgid/[email protected]
-rw-r--r--drivers/gpu/drm/i915/intel_lrc.c13
1 files changed, 13 insertions, 0 deletions
diff --git a/drivers/gpu/drm/i915/intel_lrc.c b/drivers/gpu/drm/i915/intel_lrc.c
index 8529746dd7cc..014b30ace8a0 100644
--- a/drivers/gpu/drm/i915/intel_lrc.c
+++ b/drivers/gpu/drm/i915/intel_lrc.c
@@ -779,6 +779,19 @@ static void execlists_schedule(struct drm_i915_gem_request *request, int prio)
list_safe_reset_next(dep, p, dfs_link);
}
+ /* If we didn't need to bump any existing priorities, and we haven't
+ * yet submitted this request (i.e. there is no potential race with
+ * execlists_submit_request()), we can set our own priority and skip
+ * acquiring the engine locks.
+ */
+ if (request->priotree.priority == INT_MIN) {
+ GEM_BUG_ON(!list_empty(&request->priotree.link));
+ request->priotree.priority = prio;
+ if (stack.dfs_link.next == stack.dfs_link.prev)
+ return;
+ __list_del_entry(&stack.dfs_link);
+ }
+
engine = request->engine;
spin_lock_irq(&engine->timeline->lock);