From 6670b413f8452ec303efcd2f9a6009c8602a297e Mon Sep 17 00:00:00 2001 From: Chris Wilson Date: Wed, 25 Mar 2020 12:02:26 +0000 Subject: [PATCH] drm/i915/execlists: Pull tasklet interrupt-bh local to direct submission We dropped calling process_csb prior to handling direct submission in order to avoid the nesting of spinlocks and lift process_csb() and the majority of the tasklet out of irq-off. However, we do want to avoid ksoftirqd latency in the fast path, so try and pull the interrupt-bh local to direct submission if we can acquire the tasklet's lock. v2: Document the read of pending[0] from outside the tasklet with READ_ONCE. Signed-off-by: Chris Wilson Cc: Tvrtko Ursulin Reviewed-by: Tvrtko Ursulin Link: https://patchwork.freedesktop.org/patch/msgid/20200325120227.8044-1-chris@chris-wilson.co.uk --- drivers/gpu/drm/i915/gt/intel_lrc.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/drivers/gpu/drm/i915/gt/intel_lrc.c b/drivers/gpu/drm/i915/gt/intel_lrc.c index f88d3b95c4e10..d49baade09862 100644 --- a/drivers/gpu/drm/i915/gt/intel_lrc.c +++ b/drivers/gpu/drm/i915/gt/intel_lrc.c @@ -2891,6 +2891,13 @@ static void __submit_queue_imm(struct intel_engine_cs *engine) if (reset_in_progress(execlists)) return; /* defer until we restart the engine following reset */ + /* Hopefully we clear execlists->pending[] to let us through */ + if (READ_ONCE(execlists->pending[0]) && + tasklet_trylock(&execlists->tasklet)) { + process_csb(engine); + tasklet_unlock(&execlists->tasklet); + } + __execlists_submission_tasklet(engine); } -- 2.39.5