[Intel-gfx] [PATCH] drm/i915: Be more gentle when exiting non-persistent contexts

Tvrtko Ursulin
2022-02-24T13:03:37Z

From: Tvrtko Ursulin <tvrtko.ursulin@intel.com>

When a non-persistent context exits we currently mark it as banned in
order to trigger fast termination of any outstanding GPU jobs it may have
left running.

In doing so we apply a very strict 1ms limit in which the left over job
has to preempt before we issues an engine resets.

Some workloads are not able to cleanly preempt in that time window and it
can be argued that it would instead be better to give them a bit more
grace since avoiding engine resets is generally preferrable.

To achieve this the patch splits handling of banned contexts from simply
closed non-persistent ones and then applies different timeouts for both
and also extends the criteria which determines if a request should be
scheduled back in after preemption or not.

20ms preempt timeout grace is given to exited non-persistent contexts
which have been empirically tested to satisfy customers requirements
and still provides reasonably quick cleanup post exit.

v2:
* Streamline fast path checks.

v3:
* Simplify by using only schedulable status.
* Increase timeout to 20ms.

v4:
* Fix live_execlists selftest.

v5:
* Fix logic in kill_engines.

v6:
* Rebase.

v7:
* Add GuC support.

Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Zhen Han <zhen.han@intel.com>
Cc: Matthew Brost <matthew.brost@intel.com>
Cc: John Harrison <John.C.Harrison@Intel.com>
---
drivers/gpu/drm/i915/gem/i915_gem_context.c | 22 +++++++++++-----
drivers/gpu/drm/i915/gt/intel_context.c | 25 ++++++++++++++++++
drivers/gpu/drm/i915/gt/intel_context.h | 26 ++++++++++++++-----
drivers/gpu/drm/i915/gt/intel_context_types.h | 4 ++-
.../drm/i915/gt/intel_execlists_submission.c | 13 +++++++---
.../gpu/drm/i915/gt/intel_ring_submission.c | 7 ++---
.../gpu/drm/i915/gt/uc/intel_guc_submission.c | 15 ++++++-----
drivers/gpu/drm/i915/i915_request.c | 2 +-
8 files changed, 86 insertions(+), 28 deletions(-)

diff --git a/drivers/gpu/drm/i915/gem/i915_gem_context.c b/drivers/gpu/drm/i915/gem/i915_gem_context.c
index bc6d59df064d..3a61ec753894 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_context.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_context.c
@@ -1332,7 +1332,8 @@ static struct intel_engine_cs *active_engine(struct intel_context *ce)
return engine;
}

-static void kill_engines(struct i915_gem_engines *engines, bool ban)
+static void
+kill_engines(struct i915_gem_engines *engines, bool ban, bool persistent)
{
struct i915_gem_engines_iter it;
struct intel_context *ce;
@@ -1346,8 +1347,15 @@ static void kill_engines(struct i915_gem_engines *engines, bool ban)
*/
for_each_gem_engine(ce, engines, it) {
struct intel_engine_cs *engine;
+ bool skip = false;

- if (ban && intel_context_ban(ce, NULL))
+ if (ban)
+ skip = intel_context_ban(ce, NULL);
+ else if (!persistent)
+ skip = intel_context_exit_nonpersistent(ce, NULL);
+
+ /* Already banned or non-persistent closed. */
+ if (skip)
continue;

/*
@@ -1360,7 +1368,7 @@ static void kill_engines(struct i915_gem_engines *engines, bool ban)
engine = active_engine(ce);

/* First attempt to gracefully cancel the context */
- if (engine && !__cancel_engine(engine) && ban)
+ if (engine && !__cancel_engine(engine) && (ban || !persistent))
/*
* If we are unable to send a preemptive pulse to bump
* the context from the GPU, we have to resort to a full
@@ -1372,8 +1380,6 @@ static void kill_engines(struct i915_gem_engines *engines, bool ban)

static void kill_context(struct i915_gem_context *ctx)
{
- bool ban = (!i915_gem_context_is_persistent(ctx) ||
- !ctx->i915->params.enable_hangcheck);
struct i915_gem_engines *pos, *next;

spin_lock_irq(&ctx->stale.lock);
@@ -1386,7 +1392,8 @@ static void kill_context(struct i915_gem_context *ctx)

spin_unlock_irq(&ctx->stale.lock);

- kill_engines(pos, ban);
+ kill_engines(pos, !ctx->i915->params.enable_hangcheck,
+ i915_gem_context_is_persistent(ctx));

spin_lock_irq(&ctx->stale.lock);
GEM_BUG_ON(i915_sw_fence_signaled(&pos->fence));
@@ -1432,7 +1439,8 @@ static void engines_idle_release(struct i915_gem_context *ctx,

kill:
if (list_empty(&engines->link)) /* raced, already closed */
- kill_engines(engines, true);
+ kill_engines(engines, true,
+ i915_gem_context_is_persistent(ctx));

i915_sw_fence_commit(&engines->fence);
}
diff --git a/drivers/gpu/drm/i915/gt/intel_context.c b/drivers/gpu/drm/i915/gt/intel_context.c
index 5d0ec7c49b6a..27cd71c13097 100644
--- a/drivers/gpu/drm/i915/gt/intel_context.c
+++ b/drivers/gpu/drm/i915/gt/intel_context.c
@@ -576,6 +576,31 @@ void intel_context_bind_parent_child(struct intel_context *parent,
child->parallel.parent = parent;
}

+bool intel_context_ban(struct intel_context *ce, struct i915_request *rq)
+{
+ bool ret = intel_context_set_banned(ce);
+
+ trace_intel_context_ban(ce);
+
+ if (ce->ops->revoke)
+ ce->ops->revoke(ce, rq,
+ INTEL_CONTEXT_BANNED_PREEMPT_TIMEOUT_MS);
+
+ return ret;
+}
+
+bool intel_context_exit_nonpersistent(struct intel_context *ce,
+ struct i915_request *rq)
+{
+ bool ret = intel_context_set_exiting(ce);
+
+ if (ce->ops->revoke)
+ ce->ops->revoke(ce, rq,
+ INTEL_CONTEXT_EXITING_PREEMPT_TIMEOUT_MS);
+
+ return ret;
+}
+
#if IS_ENABLED(CONFIG_DRM_I915_SELFTEST)
#include "selftest_context.c"
#endif
diff --git a/drivers/gpu/drm/i915/gt/intel_context.h b/drivers/gpu/drm/i915/gt/intel_context.h
index d8c74bbf9aae..11c95e9d76ab 100644
--- a/drivers/gpu/drm/i915/gt/intel_context.h
+++ b/drivers/gpu/drm/i915/gt/intel_context.h
@@ -25,6 +25,9 @@
##__VA_ARGS__); \
} while (0)

+#define INTEL_CONTEXT_EXITING_PREEMPT_TIMEOUT_MS (20)
+#define INTEL_CONTEXT_BANNED_PREEMPT_TIMEOUT_MS (1)
+
struct i915_gem_ww_ctx;

void intel_context_init(struct intel_context *ce,
@@ -309,18 +312,27 @@ static inline bool intel_context_set_banned(struct intel_context *ce)
return test_and_set_bit(CONTEXT_BANNED, &ce->flags);
}

-static inline bool intel_context_ban(struct intel_context *ce,
- struct i915_request *rq)
+bool intel_context_ban(struct intel_context *ce, struct i915_request *rq);
+
+static inline bool intel_context_is_schedulable(const struct intel_context *ce)
{
- bool ret = intel_context_set_banned(ce);
+ return !test_bit(CONTEXT_EXITING, &ce->flags) &&
+ !test_bit(CONTEXT_BANNED, &ce->flags);
+}

- trace_intel_context_ban(ce);
- if (ce->ops->ban)
- ce->ops->ban(ce, rq);
+static inline bool intel_context_is_exiting(const struct intel_context *ce)
+{
+ return test_bit(CONTEXT_EXITING, &ce->flags);
+}

- return ret;
+static inline bool intel_context_set_exiting(struct intel_context *ce)
+{
+ return test_and_set_bit(CONTEXT_EXITING, &ce->flags);
}

+bool intel_context_exit_nonpersistent(struct intel_context *ce,
+ struct i915_request *rq);
+
static inline bool
intel_context_force_single_submission(const struct intel_context *ce)
{
diff --git a/drivers/gpu/drm/i915/gt/intel_context_types.h b/drivers/gpu/drm/i915/gt/intel_context_types.h
index 30cd81ad8911..34073430cf8a 100644
--- a/drivers/gpu/drm/i915/gt/intel_context_types.h
+++ b/drivers/gpu/drm/i915/gt/intel_context_types.h
@@ -37,7 +37,8 @@ struct intel_context_ops {

int (*alloc)(struct intel_context *ce);

- void (*ban)(struct intel_context *ce, struct i915_request *rq);
+ void (*revoke)(struct intel_context *ce, struct i915_request *rq,
+ unsigned int preempt_timeout_ms);

int (*pre_pin)(struct intel_context *ce, struct i915_gem_ww_ctx *ww, void **vaddr);
int (*pin)(struct intel_context *ce, void *vaddr);
@@ -119,6 +120,7 @@ struct intel_context {
#define CONTEXT_GUC_INIT 10
#define CONTEXT_PERMA_PIN 11
#define CONTEXT_IS_PARKING 12
+#define CONTEXT_EXITING 13

struct {
u64 timeout_us;
diff --git a/drivers/gpu/drm/i915/gt/intel_execlists_submission.c b/drivers/gpu/drm/i915/gt/intel_execlists_submission.c
index 961d795220a3..953d1e7453c6 100644
--- a/drivers/gpu/drm/i915/gt/intel_execlists_submission.c
+++ b/drivers/gpu/drm/i915/gt/intel_execlists_submission.c
@@ -481,7 +481,7 @@ __execlists_schedule_in(struct i915_request *rq)
!intel_engine_has_heartbeat(engine)))
intel_context_set_banned(ce);

- if (unlikely(intel_context_is_banned(ce) || bad_request(rq)))
+ if (unlikely(!intel_context_is_schedulable(ce) || bad_request(rq)))
reset_active(rq, engine);

if (IS_ENABLED(CONFIG_DRM_I915_DEBUG_GEM))
@@ -1225,12 +1225,19 @@ static void record_preemption(struct intel_engine_execlists *execlists)
static unsigned long active_preempt_timeout(struct intel_engine_cs *engine,
const struct i915_request *rq)
{
+ struct intel_context *ce;
+
if (!rq)
return 0;

+ ce = rq->context;
+
/* Force a fast reset for terminated contexts (ignoring sysfs!) */
- if (unlikely(intel_context_is_banned(rq->context) || bad_request(rq)))
- return 1;
+ if (unlikely(intel_context_is_banned(ce) || bad_request(rq)))
+ return INTEL_CONTEXT_BANNED_PREEMPT_TIMEOUT_MS;
+ /* Longer grace for closed non-persistent contexts to avoid resets. */
+ else if (unlikely(intel_context_is_exiting(ce)))
+ return INTEL_CONTEXT_EXITING_PREEMPT_TIMEOUT_MS;

return READ_ONCE(engine->props.preempt_timeout_ms);
}
diff --git a/drivers/gpu/drm/i915/gt/intel_ring_submission.c b/drivers/gpu/drm/i915/gt/intel_ring_submission.c
index 6d7ec3bf1f32..a3dcc227a702 100644
--- a/drivers/gpu/drm/i915/gt/intel_ring_submission.c
+++ b/drivers/gpu/drm/i915/gt/intel_ring_submission.c
@@ -596,8 +596,9 @@ static void ring_context_reset(struct intel_context *ce)
clear_bit(CONTEXT_VALID_BIT, &ce->flags);
}

-static void ring_context_ban(struct intel_context *ce,
- struct i915_request *rq)
+static void ring_context_revoke(struct intel_context *ce,
+ struct i915_request *rq,
+ unsigned int preempt_timeout_ms)
{
struct intel_engine_cs *engine;

@@ -632,7 +633,7 @@ static const struct intel_context_ops ring_context_ops = {

.cancel_request = ring_context_cancel_request,

- .ban = ring_context_ban,
+ .revoke = ring_context_revoke,

.pre_pin = ring_context_pre_pin,
.pin = ring_context_pin,
diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
index b3a429a92c0d..23fdbc7b34ab 100644
--- a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
+++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
@@ -2602,7 +2602,9 @@ static void __guc_context_set_preemption_timeout(struct intel_guc *guc,
intel_guc_send_busy_loop(guc, action, ARRAY_SIZE(action), 0, true);
}

-static void guc_context_ban(struct intel_context *ce, struct i915_request *rq)
+static void
+guc_context_revoke(struct intel_context *ce, struct i915_request *rq,
+ unsigned int preempt_timeout_ms)
{
struct intel_guc *guc = ce_to_guc(ce);
struct intel_runtime_pm *runtime_pm =
@@ -2641,7 +2643,8 @@ static void guc_context_ban(struct intel_context *ce, struct i915_request *rq)
* gets kicked off the HW ASAP.
*/
with_intel_runtime_pm(runtime_pm, wakeref) {
- __guc_context_set_preemption_timeout(guc, guc_id, 1);
+ __guc_context_set_preemption_timeout(guc, guc_id,
+ preempt_timeout_ms);
__guc_context_sched_disable(guc, ce, guc_id);
}
} else {
@@ -2649,7 +2652,7 @@ static void guc_context_ban(struct intel_context *ce, struct i915_request *rq)
with_intel_runtime_pm(runtime_pm, wakeref)
__guc_context_set_preemption_timeout(guc,
ce->guc_id.id,
- 1);
+ preempt_timeout_ms);
spin_unlock_irqrestore(&ce->guc_state.lock, flags);
}
}
@@ -2998,7 +3001,7 @@ static const struct intel_context_ops guc_context_ops = {
.unpin = guc_context_unpin,
.post_unpin = guc_context_post_unpin,

- .ban = guc_context_ban,
+ .revoke = guc_context_revoke,

.cancel_request = guc_context_cancel_request,

@@ -3247,7 +3250,7 @@ static const struct intel_context_ops virtual_guc_context_ops = {
.unpin = guc_virtual_context_unpin,
.post_unpin = guc_context_post_unpin,

- .ban = guc_context_ban,
+ .revoke = guc_context_revoke,

.cancel_request = guc_context_cancel_request,

@@ -3336,7 +3339,7 @@ static const struct intel_context_ops virtual_parent_context_ops = {
.unpin = guc_parent_context_unpin,
.post_unpin = guc_context_post_unpin,

- .ban = guc_context_ban,
+ .revoke = guc_context_revoke,

.cancel_request = guc_context_cancel_request,

diff --git a/drivers/gpu/drm/i915/i915_request.c b/drivers/gpu/drm/i915/i915_request.c
index 582770360ad1..13c555d190a0 100644
--- a/drivers/gpu/drm/i915/i915_request.c
+++ b/drivers/gpu/drm/i915/i915_request.c
@@ -611,7 +611,7 @@ bool __i915_request_submit(struct i915_request *request)
goto active;
}

- if (unlikely(intel_context_is_banned(request->context)))
+ if (unlikely(!intel_context_is_schedulable(request->context)))
i915_request_set_error_once(request, -EIO);

if (unlikely(fatal_error(request->fence.error)))
--
2.32.0