drm/i915/execlists: Lift process_csb() out of the irq-off spinlock

If we only call process_csb() from the tasklet, though we lose the
ability to bypass ksoftirqd interrupt processing on direct submission
paths, we can push it out of the irq-off spinlock.

The penalty is that we then allow schedule_out to be called concurrently
with schedule_in requiring us to handle the usage count (baked into the
pointer itself) atomically.

As we do kick the tasklets (via local_bh_enable()) after our submission,
there is a possibility there to see if we can pull the local softirq
processing back from the ksoftirqd.

v2: Store the 'switch_priority_hint' on submission, so that we can
safely check during process_csb().

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Reviewed-by: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190816171608.11760-1-chris@chris-wilson.co.uk

1 files changed, 1 insertions, 1 deletions

diff --git a/drivers/gpu/drm/i915/gt/intel_engine_cs.c b/drivers/gpu/drm/i915/gt/intel_engine_cs.c
index 957f27a2ec97..ba457c1c7dc0 100644
--- a/drivers/gpu/drm/i915/gt/intel_engine_cs.c
+++ b/drivers/gpu/drm/i915/gt/intel_engine_cs.c
@@ -1459,7 +1459,7 @@ int intel_enable_engine_stats(struct intel_engine_cs *engine)
 
 		for (port = execlists->pending; (rq = *port); port++) {
 			/* Exclude any contexts already counted in active */
-			if (intel_context_inflight_count(rq->hw_context) == 1)
+			if (!intel_context_inflight_count(rq->hw_context))
 				engine->stats.active++;
 		}