Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> writes:
> Just in case everything fails (like for example "missed interrupt
> syndrome" on Sandybridge), always flush the submission tasklet from the
> heartbeat. This papers over such issues, but will still appear as a
> second long glitch, and prevents us from detecting it unless we happen
> to be performing a timed test.
>
> v2: We rely on flush_submission() synchronizing with the tasklet on
> another CPU.
>
> Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
> ---
> drivers/gpu/drm/i915/gt/intel_engine_cs.c | 23 +++++++++----------
> .../gpu/drm/i915/gt/intel_engine_heartbeat.c | 3 +++
> 2 files changed, 14 insertions(+), 12 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/gt/intel_engine_cs.c b/drivers/gpu/drm/i915/gt/intel_engine_cs.c
> index d613cf31970c..31049e0bdb57 100644
> --- a/drivers/gpu/drm/i915/gt/intel_engine_cs.c
> +++ b/drivers/gpu/drm/i915/gt/intel_engine_cs.c
> @@ -1094,19 +1094,18 @@ void intel_engine_flush_submission(struct intel_engine_cs *engine)
> {
> struct tasklet_struct *t = &engine->execlists.tasklet;
>
> - if (__tasklet_is_scheduled(t)) {
> - local_bh_disable();
> - if (tasklet_trylock(t)) {
> - /* Must wait for any GPU reset in progress. */
> - if (__tasklet_is_enabled(t))
> - t->func(t->data);
> - tasklet_unlock(t);
> - }
> - local_bh_enable();
> + /* Synchronise and wait for the tasklet on another CPU */
> + tasklet_kill(t);
> +
> + /* Having cancelled the tasklet, ensure that is run */
> + local_bh_disable();
> + if (tasklet_trylock(t)) {
> + /* Must wait for any GPU reset in progress. */
> + if (__tasklet_is_enabled(t))
On heartbeat context this could be an assertion I think.
But it is difficult to enforce hw sanity and still please the
user.
They will curse on glitch, even tho thye are saved!
Reviewed-by: Mika Kuoppala <mika.kuoppala@xxxxxxxxxxxxxxx>
-Mika
> + t->func(t->data);
> + tasklet_unlock(t);
> }
> -
> - /* Otherwise flush the tasklet if it was running on another cpu */
> - tasklet_unlock_wait(t);
> + local_bh_enable();
> }
>
> /**
> diff --git a/drivers/gpu/drm/i915/gt/intel_engine_heartbeat.c b/drivers/gpu/drm/i915/gt/intel_engine_heartbeat.c
> index f67ad937eefb..cd20fb549b38 100644
> --- a/drivers/gpu/drm/i915/gt/intel_engine_heartbeat.c
> +++ b/drivers/gpu/drm/i915/gt/intel_engine_heartbeat.c
> @@ -65,6 +65,9 @@ static void heartbeat(struct work_struct *wrk)
> struct intel_context *ce = engine->kernel_context;
> struct i915_request *rq;
>
> + /* Just in case everything has gone horribly wrong, give it a kick */
> + intel_engine_flush_submission(engine);
> +
> rq = engine->heartbeat.systole;
> if (rq && i915_request_completed(rq)) {
> i915_request_put(rq);
> --
> 2.20.1
>
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