[Intel-gfx] [PATCH 2/2] drm/i915/gt: Always report the sample time for busy-stats
Chris Wilson
chris at chris-wilson.co.uk
Wed Jun 17 13:09:16 UTC 2020
Return the monotonic timestamp (ktime_get()) at the time of sampling the
busy-time. This is used in preference to taking ktime_get() separately
before or after the read seqlock as there can be some large variance in
reported timestamps. For selftests trying to ascertain that we are
reporting accurate to within a few microseconds, even a small delay
leads to the test failing.
Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
---
drivers/gpu/drm/i915/gt/intel_engine.h | 3 +-
drivers/gpu/drm/i915/gt/intel_engine_cs.c | 12 ++--
drivers/gpu/drm/i915/gt/intel_rps.c | 9 ++-
drivers/gpu/drm/i915/gt/selftest_engine_pm.c | 18 +++---
drivers/gpu/drm/i915/i915_pmu.c | 5 +-
drivers/gpu/drm/i915/selftests/i915_request.c | 63 ++++++++++++-------
6 files changed, 66 insertions(+), 44 deletions(-)
diff --git a/drivers/gpu/drm/i915/gt/intel_engine.h b/drivers/gpu/drm/i915/gt/intel_engine.h
index 791897f8d847..a9249a23903a 100644
--- a/drivers/gpu/drm/i915/gt/intel_engine.h
+++ b/drivers/gpu/drm/i915/gt/intel_engine.h
@@ -334,7 +334,8 @@ void intel_engine_dump(struct intel_engine_cs *engine,
struct drm_printer *m,
const char *header, ...);
-ktime_t intel_engine_get_busy_time(struct intel_engine_cs *engine);
+ktime_t intel_engine_get_busy_time(struct intel_engine_cs *engine,
+ ktime_t *now);
struct i915_request *
intel_engine_find_active_request(struct intel_engine_cs *engine);
diff --git a/drivers/gpu/drm/i915/gt/intel_engine_cs.c b/drivers/gpu/drm/i915/gt/intel_engine_cs.c
index 045179c65c44..c62b3cbdbbf9 100644
--- a/drivers/gpu/drm/i915/gt/intel_engine_cs.c
+++ b/drivers/gpu/drm/i915/gt/intel_engine_cs.c
@@ -1595,7 +1595,8 @@ void intel_engine_dump(struct intel_engine_cs *engine,
intel_engine_print_breadcrumbs(engine, m);
}
-static ktime_t __intel_engine_get_busy_time(struct intel_engine_cs *engine)
+static ktime_t __intel_engine_get_busy_time(struct intel_engine_cs *engine,
+ ktime_t *now)
{
ktime_t total = engine->stats.total;
@@ -1603,9 +1604,9 @@ static ktime_t __intel_engine_get_busy_time(struct intel_engine_cs *engine)
* If the engine is executing something at the moment
* add it to the total.
*/
+ *now = ktime_get();
if (atomic_read(&engine->stats.active))
- total = ktime_add(total,
- ktime_sub(ktime_get(), engine->stats.start));
+ total = ktime_add(total, ktime_sub(*now, engine->stats.start));
return total;
}
@@ -1613,17 +1614,18 @@ static ktime_t __intel_engine_get_busy_time(struct intel_engine_cs *engine)
/**
* intel_engine_get_busy_time() - Return current accumulated engine busyness
* @engine: engine to report on
+ * @now: monotonic timestamp of sampling
*
* Returns accumulated time @engine was busy since engine stats were enabled.
*/
-ktime_t intel_engine_get_busy_time(struct intel_engine_cs *engine)
+ktime_t intel_engine_get_busy_time(struct intel_engine_cs *engine, ktime_t *now)
{
unsigned int seq;
ktime_t total;
do {
seq = read_seqbegin(&engine->stats.lock);
- total = __intel_engine_get_busy_time(engine);
+ total = __intel_engine_get_busy_time(engine, now);
} while (read_seqretry(&engine->stats.lock, seq));
return total;
diff --git a/drivers/gpu/drm/i915/gt/intel_rps.c b/drivers/gpu/drm/i915/gt/intel_rps.c
index 2f59fc6df3c2..bdece932592b 100644
--- a/drivers/gpu/drm/i915/gt/intel_rps.c
+++ b/drivers/gpu/drm/i915/gt/intel_rps.c
@@ -53,13 +53,13 @@ static void rps_timer(struct timer_list *t)
struct intel_engine_cs *engine;
enum intel_engine_id id;
s64 max_busy[3] = {};
- ktime_t dt, last;
+ ktime_t dt, timestamp, last;
for_each_engine(engine, rps_to_gt(rps), id) {
s64 busy;
int i;
- dt = intel_engine_get_busy_time(engine);
+ dt = intel_engine_get_busy_time(engine, ×tamp);
last = engine->stats.rps;
engine->stats.rps = dt;
@@ -70,15 +70,14 @@ static void rps_timer(struct timer_list *t)
}
}
- dt = ktime_get();
last = rps->pm_timestamp;
- rps->pm_timestamp = dt;
+ rps->pm_timestamp = timestamp;
if (intel_rps_is_active(rps)) {
s64 busy;
int i;
- dt = ktime_sub(dt, last);
+ dt = ktime_sub(timestamp, last);
/*
* Our goal is to evaluate each engine independently, so we run
diff --git a/drivers/gpu/drm/i915/gt/selftest_engine_pm.c b/drivers/gpu/drm/i915/gt/selftest_engine_pm.c
index dd54dcb5cca2..b08fc5390e8a 100644
--- a/drivers/gpu/drm/i915/gt/selftest_engine_pm.c
+++ b/drivers/gpu/drm/i915/gt/selftest_engine_pm.c
@@ -29,8 +29,8 @@ static int live_engine_busy_stats(void *arg)
GEM_BUG_ON(intel_gt_pm_is_awake(gt));
for_each_engine(engine, gt, id) {
struct i915_request *rq;
- ktime_t de;
- u64 dt;
+ ktime_t de, dt;
+ ktime_t t[2];
if (!intel_engine_supports_stats(engine))
continue;
@@ -47,12 +47,11 @@ static int live_engine_busy_stats(void *arg)
ENGINE_TRACE(engine, "measuring idle time\n");
preempt_disable();
- dt = ktime_to_ns(ktime_get());
- de = intel_engine_get_busy_time(engine);
+ de = intel_engine_get_busy_time(engine, &t[0]);
udelay(100);
- de = ktime_sub(intel_engine_get_busy_time(engine), de);
- dt = ktime_to_ns(ktime_get()) - dt;
+ de = ktime_sub(intel_engine_get_busy_time(engine, &t[1]), de);
preempt_enable();
+ dt = ktime_sub(t[1], t[0]);
if (de < 0 || de > 10) {
pr_err("%s: reported %lldns [%d%%] busyness while sleeping [for %lldns]\n",
engine->name,
@@ -80,12 +79,11 @@ static int live_engine_busy_stats(void *arg)
ENGINE_TRACE(engine, "measuring busy time\n");
preempt_disable();
- dt = ktime_to_ns(ktime_get());
- de = intel_engine_get_busy_time(engine);
+ de = intel_engine_get_busy_time(engine, &t[0]);
udelay(100);
- de = ktime_sub(intel_engine_get_busy_time(engine), de);
- dt = ktime_to_ns(ktime_get()) - dt;
+ de = ktime_sub(intel_engine_get_busy_time(engine, &t[1]), de);
preempt_enable();
+ dt = ktime_sub(t[1], t[0]);
if (100 * de < 95 * dt || 95 * de > 100 * dt) {
pr_err("%s: reported %lldns [%d%%] busyness while spinning [for %lldns]\n",
engine->name,
diff --git a/drivers/gpu/drm/i915/i915_pmu.c b/drivers/gpu/drm/i915/i915_pmu.c
index 802837de1767..28bc5f13ae52 100644
--- a/drivers/gpu/drm/i915/i915_pmu.c
+++ b/drivers/gpu/drm/i915/i915_pmu.c
@@ -565,7 +565,10 @@ static u64 __i915_pmu_event_read(struct perf_event *event)
/* Do nothing */
} else if (sample == I915_SAMPLE_BUSY &&
intel_engine_supports_stats(engine)) {
- val = ktime_to_ns(intel_engine_get_busy_time(engine));
+ ktime_t unused;
+
+ val = ktime_to_ns(intel_engine_get_busy_time(engine,
+ &unused));
} else {
val = engine->pmu.sample[sample].cur;
}
diff --git a/drivers/gpu/drm/i915/selftests/i915_request.c b/drivers/gpu/drm/i915/selftests/i915_request.c
index 06d18aae070b..9271aad7f779 100644
--- a/drivers/gpu/drm/i915/selftests/i915_request.c
+++ b/drivers/gpu/drm/i915/selftests/i915_request.c
@@ -2492,9 +2492,11 @@ static int perf_series_engines(void *arg)
intel_engine_pm_get(p->engine);
if (intel_engine_supports_stats(p->engine))
- p->busy = intel_engine_get_busy_time(p->engine) + 1;
+ p->busy = intel_engine_get_busy_time(p->engine,
+ &p->time) + 1;
+ else
+ p->time = ktime_get();
p->runtime = -intel_context_get_total_runtime_ns(ce);
- p->time = ktime_get();
}
err = (*fn)(ps);
@@ -2505,13 +2507,15 @@ static int perf_series_engines(void *arg)
struct perf_stats *p = &stats[idx];
struct intel_context *ce = ps->ce[idx];
int integer, decimal;
- u64 busy, dt;
+ u64 busy, dt, now;
- p->time = ktime_sub(ktime_get(), p->time);
- if (p->busy) {
- p->busy = ktime_sub(intel_engine_get_busy_time(p->engine),
+ if (p->busy)
+ p->busy = ktime_sub(intel_engine_get_busy_time(p->engine,
+ &now),
p->busy - 1);
- }
+ else
+ now = ktime_get();
+ p->time = ktime_sub(now, p->time);
err = switch_to_kernel_sync(ce, err);
p->runtime += intel_context_get_total_runtime_ns(ce);
@@ -2571,13 +2575,14 @@ static int p_sync0(void *arg)
return err;
}
- busy = false;
if (intel_engine_supports_stats(engine)) {
- p->busy = intel_engine_get_busy_time(engine);
+ p->busy = intel_engine_get_busy_time(engine, &p->time);
busy = true;
+ } else {
+ p->time = ktime_get();
+ busy = false;
}
- p->time = ktime_get();
count = 0;
do {
struct i915_request *rq;
@@ -2600,11 +2605,15 @@ static int p_sync0(void *arg)
count++;
} while (!__igt_timeout(end_time, NULL));
- p->time = ktime_sub(ktime_get(), p->time);
if (busy) {
- p->busy = ktime_sub(intel_engine_get_busy_time(engine),
+ ktime_t now;
+
+ p->busy = ktime_sub(intel_engine_get_busy_time(engine, &now),
p->busy);
+ p->time = ktime_sub(now, p->time);
+ } else {
+ p->time = ktime_sub(ktime_get(), p->time);
}
err = switch_to_kernel_sync(ce, err);
@@ -2637,13 +2646,14 @@ static int p_sync1(void *arg)
return err;
}
- busy = false;
if (intel_engine_supports_stats(engine)) {
- p->busy = intel_engine_get_busy_time(engine);
+ p->busy = intel_engine_get_busy_time(engine, &p->time);
busy = true;
+ } else {
+ p->time = ktime_get();
+ busy = false;
}
- p->time = ktime_get();
count = 0;
do {
struct i915_request *rq;
@@ -2668,11 +2678,15 @@ static int p_sync1(void *arg)
count++;
} while (!__igt_timeout(end_time, NULL));
i915_request_put(prev);
- p->time = ktime_sub(ktime_get(), p->time);
if (busy) {
- p->busy = ktime_sub(intel_engine_get_busy_time(engine),
+ ktime_t now;
+
+ p->busy = ktime_sub(intel_engine_get_busy_time(engine, &now),
p->busy);
+ p->time = ktime_sub(now, p->time);
+ } else {
+ p->time = ktime_sub(ktime_get(), p->time);
}
err = switch_to_kernel_sync(ce, err);
@@ -2704,14 +2718,15 @@ static int p_many(void *arg)
return err;
}
- busy = false;
if (intel_engine_supports_stats(engine)) {
- p->busy = intel_engine_get_busy_time(engine);
+ p->busy = intel_engine_get_busy_time(engine, &p->time);
busy = true;
+ } else {
+ p->time = ktime_get();
+ busy = false;
}
count = 0;
- p->time = ktime_get();
do {
struct i915_request *rq;
@@ -2724,11 +2739,15 @@ static int p_many(void *arg)
i915_request_add(rq);
count++;
} while (!__igt_timeout(end_time, NULL));
- p->time = ktime_sub(ktime_get(), p->time);
if (busy) {
- p->busy = ktime_sub(intel_engine_get_busy_time(engine),
+ ktime_t now;
+
+ p->busy = ktime_sub(intel_engine_get_busy_time(engine, &now),
p->busy);
+ p->time = ktime_sub(now, p->time);
+ } else {
+ p->time = ktime_sub(ktime_get(), p->time);
}
err = switch_to_kernel_sync(ce, err);
--
2.20.1
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