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drm/i915: Make the heartbeat play nice with long pre-emption timeouts

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Compute workloads are inherently not pre-emptible for long periods on
current hardware. As a workaround for this, the pre-emption timeout
for compute capable engines was disabled. This is undesirable with GuC
submission as it prevents per engine reset of hung contexts. Hence the
next patch will re-enable the timeout but bumped up by an order of
magnitude.

However, the heartbeat might not respect that. Depending upon current
activity, a pre-emption to the heartbeat pulse might not even be
attempted until the last heartbeat period. Which means that only one
period is granted for the pre-emption to occur. With the aforesaid
bump, the pre-emption timeout could be significantly larger than this
heartbeat period.

So adjust the heartbeat code to take the pre-emption timeout into
account. When it reaches the final (high priority) period, it now
ensures the delay before hitting reset is bigger than the pre-emption
timeout.

v2: Fix for selftests which adjust the heartbeat period manually.
v3: Add FIXME comment about selftests. Add extra FIXME comment and
drm_notices when setting heartbeat to a non-default value (review
feedback from Tvrtko)

Signed-off-by: John Harrison <John.C.Harrison@Intel.com>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20221006213813.1563435-4-John.C.Harrison@Intel.com
This commit is contained in:
John Harrison 2022-10-06 14:38:12 -07:00
parent c3bd49cd9a
commit 47daf84a8b
1 changed files with 39 additions and 0 deletions
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39
drivers/gpu/drm/i915/gt/intel_engine_heartbeat.c
View File

@ -22,9 +22,37 @@
static bool next_heartbeat(struct intel_engine_cs *engine)
{
struct i915_request *rq;
long delay;
delay = READ_ONCE(engine->props.heartbeat_interval_ms);
rq = engine->heartbeat.systole;
/*
* FIXME: The final period extension is disabled if the period has been
* modified from the default. This is to prevent issues with certain
* selftests which override the value and expect specific behaviour.
* Once the selftests have been updated to either cope with variable
* heartbeat periods (or to override the pre-emption timeout as well,
* or just to add a selftest specific override of the extension), the
* generic override can be removed.
*/
if (rq && rq->sched.attr.priority >= I915_PRIORITY_BARRIER &&
delay == engine->defaults.heartbeat_interval_ms) {
long longer;
/*
* The final try is at the highest priority possible. Up until now
* a pre-emption might not even have been attempted. So make sure
* this last attempt allows enough time for a pre-emption to occur.
*/
longer = READ_ONCE(engine->props.preempt_timeout_ms) * 2;
longer = intel_clamp_heartbeat_interval_ms(engine, longer);
if (longer > delay)
delay = longer;
}
if (!delay)
return false;
@ -288,6 +316,17 @@ int intel_engine_set_heartbeat(struct intel_engine_cs *engine,
if (!delay && !intel_engine_has_preempt_reset(engine))
return -ENODEV;
/* FIXME: Remove together with equally marked hack in next_heartbeat. */
if (delay != engine->defaults.heartbeat_interval_ms &&
delay < 2 * engine->props.preempt_timeout_ms) {
if (intel_engine_uses_guc(engine))
drm_notice(&engine->i915->drm, "%s heartbeat interval adjusted to a non-default value which may downgrade individual engine resets to full GPU resets!\n",
engine->name);
else
drm_notice(&engine->i915->drm, "%s heartbeat interval adjusted to a non-default value which may cause engine resets to target innocent contexts!\n",
engine->name);
}
intel_engine_pm_get(engine);
err = mutex_lock_interruptible(&ce->timeline->mutex);