diff options
| author | Chris Wilson <chris@chris-wilson.co.uk> | 2019-12-19 12:43:53 +0000 |
|---|---|---|
| committer | Chris Wilson <chris@chris-wilson.co.uk> | 2019-12-19 17:03:57 +0000 |
| commit | b81e4d9b594188a8babf06442e1d6f28de78c68f (patch) | |
| tree | a2f4dc6ce2faaa850074a0d0c1b6d165157e2099 /drivers/gpu/drm/i915/gt/intel_engine_cs.c | |
| parent | dc93c9b69315167f5678b94aa911dc8e7c299fe5 (diff) | |
drm/i915/gt: Track engine round-trip times
Knowing the round trip time of an engine is useful for tracking the
health of the system as well as providing a metric for the baseline
responsiveness of the engine. We can use the latter metric for
automatically tuning our waits in selftests and when idling so we don't
confuse a slower system with a dead one.
Upon idling the engine, we send one last pulse to switch the context
away from precious user state to the volatile kernel context. We know
the engine is idle at this point, and the pulse is non-preemptible, so
this provides us with a good measurement of the round trip time. It also
provides us with faster engine parking for ringbuffer submission, which
is a welcome bonus (e.g. softer-rc6).
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Cc: Stuart Summers <stuart.summers@intel.com>
Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191219105043.4169050-1-chris@chris-wilson.co.uk
Link: https://patchwork.freedesktop.org/patch/msgid/20191219124353.8607-2-chris@chris-wilson.co.uk
Diffstat (limited to 'drivers/gpu/drm/i915/gt/intel_engine_cs.c')
| -rw-r--r-- | drivers/gpu/drm/i915/gt/intel_engine_cs.c | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/drivers/gpu/drm/i915/gt/intel_engine_cs.c b/drivers/gpu/drm/i915/gt/intel_engine_cs.c index 3d1d48bf90cf..6dd18f93d45c 100644 --- a/drivers/gpu/drm/i915/gt/intel_engine_cs.c +++ b/drivers/gpu/drm/i915/gt/intel_engine_cs.c @@ -334,6 +334,7 @@ static int intel_engine_setup(struct intel_gt *gt, enum intel_engine_id id) /* Nothing to do here, execute in order of dependencies */ engine->schedule = NULL; + ewma__engine_latency_init(&engine->latency); seqlock_init(&engine->stats.lock); ATOMIC_INIT_NOTIFIER_HEAD(&engine->context_status_notifier); @@ -1481,6 +1482,8 @@ void intel_engine_dump(struct intel_engine_cs *engine, drm_printf(m, "\tAwake? %d\n", atomic_read(&engine->wakeref.count)); drm_printf(m, "\tBarriers?: %s\n", yesno(!llist_empty(&engine->barrier_tasks))); + drm_printf(m, "\tLatency: %luus\n", + ewma__engine_latency_read(&engine->latency)); rcu_read_lock(); rq = READ_ONCE(engine->heartbeat.systole); |