[Intel-gfx] [PATCH] drm/i915/selftests: Measure dispatch latency
Chris Wilson
chris at chris-wilson.co.uk
Fri May 15 17:58:32 UTC 2020
A useful metric of the system's health is how fast we can tell the GPU
to do various actions, so measure our latency.
Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
Cc: Mika Kuoppala <mika.kuoppala at linux.intel.com>
---
drivers/gpu/drm/i915/selftests/i915_request.c | 612 ++++++++++++++++++
1 file changed, 612 insertions(+)
diff --git a/drivers/gpu/drm/i915/selftests/i915_request.c b/drivers/gpu/drm/i915/selftests/i915_request.c
index 6014e8dfcbb1..c265501c26a8 100644
--- a/drivers/gpu/drm/i915/selftests/i915_request.c
+++ b/drivers/gpu/drm/i915/selftests/i915_request.c
@@ -24,16 +24,20 @@
#include <linux/prime_numbers.h>
#include <linux/pm_qos.h>
+#include <linux/sort.h>
#include "gem/i915_gem_pm.h"
#include "gem/selftests/mock_context.h"
+#include "gt/intel_engine_heartbeat.h"
#include "gt/intel_engine_pm.h"
#include "gt/intel_engine_user.h"
#include "gt/intel_gt.h"
+#include "gt/intel_gt_requests.h"
#include "i915_random.h"
#include "i915_selftest.h"
+#include "igt_flush_test.h"
#include "igt_live_test.h"
#include "igt_spinner.h"
#include "lib_sw_fence.h"
@@ -1524,6 +1528,613 @@ struct perf_series {
struct intel_context *ce[];
};
+#define COUNT 5
+
+static int cmp_u32(const void *A, const void *B)
+{
+ const u32 *a = A, *b = B;
+
+ return *a - *b;
+}
+
+static u32 trifilter(u32 *a)
+{
+ u64 sum;
+
+ sort(a, COUNT, sizeof(*a), cmp_u32, NULL);
+
+ sum = mul_u32_u32(a[2], 2);
+ sum += a[1];
+ sum += a[3];
+
+ return (sum + 2) >> 2;
+}
+
+static u64 cycles_to_ns(struct intel_engine_cs *engine, u32 cycles)
+{
+ u64 ns = i915_cs_timestamp_ticks_to_ns(engine->i915, cycles);
+
+ return DIV_ROUND_CLOSEST(ns, 1 << COUNT);
+}
+
+static int measure_semaphore_response(struct intel_context *ce)
+{
+ u32 *sema = memset32(ce->engine->status_page.addr + 1000, 0, 21);
+ const u32 offset =
+ i915_ggtt_offset(ce->engine->status_page.vma) +
+ offset_in_page(sema);
+ u32 elapsed[COUNT], cycles;
+ struct i915_request *rq;
+ u32 *cs;
+ int i;
+
+ rq = i915_request_create(ce);
+ if (IS_ERR(rq))
+ return PTR_ERR(rq);
+
+ cs = intel_ring_begin(rq, 4 + 8 * ARRAY_SIZE(elapsed));
+ if (IS_ERR(cs)) {
+ i915_request_add(rq);
+ return PTR_ERR(cs);
+ }
+
+ *cs++ = MI_STORE_DWORD_IMM_GEN4 | MI_USE_GGTT;
+ *cs++ = offset;
+ *cs++ = 0;
+ *cs++ = 0xffffffff;
+
+ for (i = 1; i <= ARRAY_SIZE(elapsed); i++) {
+ *cs++ = MI_SEMAPHORE_WAIT |
+ MI_SEMAPHORE_GLOBAL_GTT |
+ MI_SEMAPHORE_POLL |
+ MI_SEMAPHORE_SAD_EQ_SDD;
+ *cs++ = i;
+ *cs++ = offset;
+ *cs++ = 0;
+
+ *cs++ = MI_STORE_REGISTER_MEM_GEN8 | MI_USE_GGTT;
+ *cs++ = ce->engine->mmio_base + 0x358;
+ *cs++ = offset + sizeof(*sema) * i;
+ *cs++ = 0;
+ }
+
+ intel_ring_advance(rq, cs);
+ i915_request_add(rq);
+
+ if (wait_for(READ_ONCE(*sema) == 0xffffffff, 50)) {
+ intel_gt_set_wedged(ce->engine->gt);
+ return -EIO;
+ }
+
+ for (i = 1; i <= ARRAY_SIZE(elapsed); i++) {
+ cycles = ENGINE_READ_FW(ce->engine, RING_TIMESTAMP);
+ WRITE_ONCE(sema[0], i);
+ wmb(); /* flush the update to the cache, and beyond */
+
+ if (wait_for(READ_ONCE(sema[i]), 50)) {
+ intel_gt_set_wedged(ce->engine->gt);
+ return -EIO;
+ }
+
+ elapsed[i - 1] = (sema[i] - cycles) << COUNT;
+ }
+
+ cycles = trifilter(elapsed);
+ pr_info("%s: semaphore response %d cycles, %lluns\n",
+ ce->engine->name, cycles >> COUNT,
+ cycles_to_ns(ce->engine, cycles));
+
+ return intel_gt_wait_for_idle(ce->engine->gt, HZ);
+}
+
+static int measure_idle_dispatch(struct intel_context *ce)
+{
+ u32 *sema = memset32(ce->engine->status_page.addr + 1000, 0, 21);
+ const u32 offset =
+ i915_ggtt_offset(ce->engine->status_page.vma) +
+ offset_in_page(sema);
+ u32 elapsed[COUNT], cycles;
+ u32 *cs;
+ int i;
+
+ for (i = 0; i < ARRAY_SIZE(elapsed); i++) {
+ struct i915_request *rq;
+ int err;
+
+ err = intel_gt_wait_for_idle(ce->engine->gt, HZ / 2);
+ if (err)
+ return err;
+
+ rq = i915_request_create(ce);
+ if (IS_ERR(rq))
+ return PTR_ERR(rq);
+
+ cs = intel_ring_begin(rq, 4);
+ if (IS_ERR(cs)) {
+ i915_request_add(rq);
+ return PTR_ERR(cs);
+ }
+
+ *cs++ = MI_STORE_REGISTER_MEM_GEN8 | MI_USE_GGTT;
+ *cs++ = ce->engine->mmio_base + 0x358;
+ *cs++ = offset + sizeof(*sema) * i;
+ *cs++ = 0;
+
+ intel_ring_advance(rq, cs);
+
+ preempt_disable();
+ local_bh_disable();
+ elapsed[i] = ENGINE_READ_FW(ce->engine, RING_TIMESTAMP);
+ i915_request_add(rq);
+ local_bh_enable();
+ preempt_enable();
+ }
+
+ for (i = 0; i < ARRAY_SIZE(elapsed); i++) {
+ if (wait_for(READ_ONCE(sema[i]), 50)) {
+ intel_gt_set_wedged(ce->engine->gt);
+ return -EIO;
+ }
+
+ elapsed[i] = (sema[i] - elapsed[i]) << COUNT;
+ }
+
+ cycles = trifilter(elapsed);
+ pr_info("%s: idle dispatch latency %d cycles, %lluns\n",
+ ce->engine->name, cycles >> COUNT,
+ cycles_to_ns(ce->engine, cycles));
+
+ return intel_gt_wait_for_idle(ce->engine->gt, HZ);
+}
+
+static int measure_busy_dispatch(struct intel_context *ce)
+{
+ u32 *sema = memset32(ce->engine->status_page.addr + 1000, 0, 21);
+ const u32 offset =
+ i915_ggtt_offset(ce->engine->status_page.vma) +
+ offset_in_page(sema);
+ u32 elapsed[COUNT + 1], cycles;
+ u32 *cs;
+ int i;
+
+ for (i = 1; i <= ARRAY_SIZE(elapsed); i++) {
+ struct i915_request *rq;
+
+ rq = i915_request_create(ce);
+ if (IS_ERR(rq))
+ return PTR_ERR(rq);
+
+ cs = intel_ring_begin(rq, 12);
+ if (IS_ERR(cs)) {
+ i915_request_add(rq);
+ return PTR_ERR(cs);
+ }
+
+ *cs++ = MI_STORE_REGISTER_MEM_GEN8 | MI_USE_GGTT;
+ *cs++ = ce->engine->mmio_base + 0x358;
+ *cs++ = offset + sizeof(*sema) * i;
+ *cs++ = 0;
+
+ *cs++ = MI_SEMAPHORE_WAIT |
+ MI_SEMAPHORE_GLOBAL_GTT |
+ MI_SEMAPHORE_POLL |
+ MI_SEMAPHORE_SAD_GTE_SDD;
+ *cs++ = i;
+ *cs++ = offset;
+ *cs++ = 0;
+
+ *cs++ = MI_STORE_REGISTER_MEM_GEN8 | MI_USE_GGTT;
+ *cs++ = ce->engine->mmio_base + 0x358;
+ *cs++ = offset + sizeof(*sema) * i;
+ *cs++ = 0;
+
+ intel_ring_advance(rq, cs);
+
+ if (i > 1 && wait_for(READ_ONCE(sema[i - 1]), 500)) {
+ intel_gt_set_wedged(ce->engine->gt);
+ return -EIO;
+ }
+
+ preempt_disable();
+ local_bh_disable();
+ elapsed[i - 1] = ENGINE_READ_FW(ce->engine, RING_TIMESTAMP);
+ i915_request_add(rq);
+ local_bh_enable();
+ WRITE_ONCE(sema[0], i - 1);
+ wmb(); /* flush the update to the cache, and beyond */
+ preempt_enable();
+ }
+ WRITE_ONCE(sema[0], i - 1);
+
+ for (i = 1; i <= COUNT; i++)
+ elapsed[i - 1] = (sema[i] - elapsed[i]) << COUNT;
+
+ cycles = trifilter(elapsed);
+ pr_info("%s: busy dispatch latency %d cycles, %lluns\n",
+ ce->engine->name, cycles >> COUNT,
+ cycles_to_ns(ce->engine, cycles));
+
+ return intel_gt_wait_for_idle(ce->engine->gt, HZ);
+}
+
+static int plug(struct intel_engine_cs *engine, u32 *sema, u32 mode, int value)
+{
+ const u32 offset =
+ i915_ggtt_offset(engine->status_page.vma) +
+ offset_in_page(sema);
+ struct i915_request *rq;
+ u32 *cs;
+
+ rq = i915_request_create(engine->kernel_context);
+ if (IS_ERR(rq))
+ return PTR_ERR(rq);
+
+ cs = intel_ring_begin(rq, 4);
+ if (IS_ERR(cs)) {
+ i915_request_add(rq);
+ return PTR_ERR(cs);
+ }
+
+ *cs++ = MI_SEMAPHORE_WAIT |
+ MI_SEMAPHORE_GLOBAL_GTT |
+ MI_SEMAPHORE_POLL |
+ mode;
+ *cs++ = value;
+ *cs++ = offset;
+ *cs++ = 0;
+
+ intel_ring_advance(rq, cs);
+ i915_request_add(rq);
+
+ return 0;
+}
+
+static int measure_inter_request(struct intel_context *ce)
+{
+ u32 *sema = memset32(ce->engine->status_page.addr + 1000, 0, 21);
+ const u32 offset =
+ i915_ggtt_offset(ce->engine->status_page.vma) +
+ offset_in_page(sema);
+ u32 elapsed[COUNT + 1], cycles;
+ struct i915_sw_fence *submit;
+ int i, err;
+
+ err = plug(ce->engine, sema, MI_SEMAPHORE_SAD_NEQ_SDD, 0);
+ if (err)
+ return err;
+
+ submit = heap_fence_create(GFP_KERNEL);
+ if (!submit) {
+ WRITE_ONCE(sema[0], 1);
+ return -ENOMEM;
+ }
+
+ intel_engine_flush_submission(ce->engine);
+ for (i = 1; i <= ARRAY_SIZE(elapsed); i++) {
+ struct i915_request *rq;
+ u32 *cs;
+
+ rq = i915_request_create(ce);
+ if (IS_ERR(rq)) {
+ WRITE_ONCE(sema[0], 1);
+ return PTR_ERR(rq);
+ }
+
+ err = i915_sw_fence_await_sw_fence_gfp(&rq->submit,
+ submit,
+ GFP_KERNEL);
+ if (err < 0) {
+ i915_sw_fence_commit(submit);
+ heap_fence_put(submit);
+ i915_request_add(rq);
+ WRITE_ONCE(sema[0], 1);
+ return err;
+ }
+
+ cs = intel_ring_begin(rq, 4);
+ if (IS_ERR(cs)) {
+ i915_sw_fence_commit(submit);
+ heap_fence_put(submit);
+ i915_request_add(rq);
+ WRITE_ONCE(sema[0], 1);
+ return PTR_ERR(cs);
+ }
+
+ *cs++ = MI_STORE_REGISTER_MEM_GEN8 | MI_USE_GGTT;
+ *cs++ = ce->engine->mmio_base + 0x358;
+ *cs++ = offset + sizeof(*sema) * i;
+ *cs++ = 0;
+
+ intel_ring_advance(rq, cs);
+ i915_request_add(rq);
+ }
+ local_bh_disable();
+ i915_sw_fence_commit(submit);
+ local_bh_enable();
+ intel_engine_flush_submission(ce->engine);
+ heap_fence_put(submit);
+
+ WRITE_ONCE(sema[0], 1);
+ wmb(); /* flush the update to the cache, and beyond */
+
+ if (wait_for(READ_ONCE(sema[COUNT + 1]), 100)) {
+ intel_gt_set_wedged(ce->engine->gt);
+ return -EIO;
+ }
+
+ for (i = 1; i <= COUNT; i++)
+ elapsed[i - 1] = (sema[i + 1] - sema[i]) << COUNT;
+
+ cycles = trifilter(elapsed);
+ pr_info("%s: inter-request latency %d cycles, %lluns\n",
+ ce->engine->name, cycles >> COUNT,
+ cycles_to_ns(ce->engine, cycles));
+
+ return intel_gt_wait_for_idle(ce->engine->gt, HZ);
+}
+
+static int measure_context_switch(struct intel_context *ce)
+{
+ u32 *sema = memset32(ce->engine->status_page.addr + 1000, 0, 21);
+ const u32 offset =
+ i915_ggtt_offset(ce->engine->status_page.vma) +
+ offset_in_page(sema);
+ struct i915_request *fence = NULL;
+ u32 elapsed[COUNT + 1], cycles;
+ int i, j, err;
+ u32 *cs;
+
+ err = plug(ce->engine, sema, MI_SEMAPHORE_SAD_NEQ_SDD, 0);
+ if (err)
+ return err;
+
+ for (i = 1; i <= ARRAY_SIZE(elapsed); i++) {
+ struct intel_context *arr[] = {
+ ce, ce->engine->kernel_context
+ };
+
+ for (j = 0; j < ARRAY_SIZE(arr); j++) {
+ struct i915_request *rq;
+
+ rq = i915_request_create(arr[j]);
+ if (IS_ERR(rq))
+ return PTR_ERR(rq);
+
+ if (fence) {
+ err = i915_request_await_dma_fence(rq,
+ &fence->fence);
+ if (err) {
+ i915_request_add(rq);
+ return err;
+ }
+ }
+
+ cs = intel_ring_begin(rq, 4);
+ if (IS_ERR(cs)) {
+ i915_request_add(rq);
+ return PTR_ERR(cs);
+ }
+
+ *cs++ = MI_STORE_REGISTER_MEM_GEN8 | MI_USE_GGTT;
+ *cs++ = ce->engine->mmio_base + 0x358;
+ *cs++ = offset +
+ sizeof(*sema) * (ARRAY_SIZE(arr) * i + j);
+ *cs++ = 0;
+
+ intel_ring_advance(rq, cs);
+
+ i915_request_put(fence);
+ fence = i915_request_get(rq);
+
+ i915_request_add(rq);
+ }
+ }
+ i915_request_put(fence);
+ intel_engine_flush_submission(ce->engine);
+
+ WRITE_ONCE(sema[0], 1);
+ wmb(); /* flush the update to the cache, and beyond */
+
+ if (wait_for(READ_ONCE(sema[2 *i - 1]), 500)) {
+ intel_gt_set_wedged(ce->engine->gt);
+ return -EIO;
+ }
+
+ for (i = 1; i <= COUNT; i++)
+ elapsed[i - 1] = (sema[2 * i + 2] - sema[2 * i + 1]) << COUNT;
+
+ cycles = trifilter(elapsed);
+ pr_info("%s: context switch latency %d cycles, %lluns\n",
+ ce->engine->name, cycles >> COUNT,
+ cycles_to_ns(ce->engine, cycles));
+
+ return intel_gt_wait_for_idle(ce->engine->gt, HZ);
+}
+
+struct signal_cb {
+ struct dma_fence_cb base;
+ bool seen;
+};
+
+static void signal_cb(struct dma_fence *fence, struct dma_fence_cb *cb)
+{
+ struct signal_cb *s = container_of(cb, typeof(*s), base);
+
+ smp_store_mb(s->seen, true); /* be safe, be strong */
+}
+
+static int measure_completion(struct intel_context *ce)
+{
+ u32 *sema = memset32(ce->engine->status_page.addr + 1000, 0, 21);
+ const u32 offset =
+ i915_ggtt_offset(ce->engine->status_page.vma) +
+ offset_in_page(sema);
+ u32 elapsed[COUNT], cycles;
+ u32 *cs;
+ int i;
+
+ for (i = 1; i <= ARRAY_SIZE(elapsed); i++) {
+ struct signal_cb cb = { .seen = false };
+ struct i915_request *rq;
+
+ rq = i915_request_create(ce);
+ if (IS_ERR(rq))
+ return PTR_ERR(rq);
+
+ cs = intel_ring_begin(rq, 12);
+ if (IS_ERR(cs)) {
+ i915_request_add(rq);
+ return PTR_ERR(cs);
+ }
+
+ *cs++ = MI_STORE_REGISTER_MEM_GEN8 | MI_USE_GGTT;
+ *cs++ = ce->engine->mmio_base + 0x358;
+ *cs++ = offset + sizeof(*sema) * i;
+ *cs++ = 0;
+
+ *cs++ = MI_SEMAPHORE_WAIT |
+ MI_SEMAPHORE_GLOBAL_GTT |
+ MI_SEMAPHORE_POLL |
+ MI_SEMAPHORE_SAD_EQ_SDD;
+ *cs++ = i;
+ *cs++ = offset;
+ *cs++ = 0;
+
+ *cs++ = MI_STORE_REGISTER_MEM_GEN8 | MI_USE_GGTT;
+ *cs++ = ce->engine->mmio_base + 0x358;
+ *cs++ = offset + sizeof(*sema) * i;
+ *cs++ = 0;
+
+ intel_ring_advance(rq, cs);
+
+ dma_fence_add_callback(&rq->fence, &cb.base, signal_cb);
+
+ local_bh_disable();
+ i915_request_add(rq);
+ local_bh_enable();
+
+ if (wait_for(READ_ONCE(sema[i]), 50)) {
+ intel_gt_set_wedged(ce->engine->gt);
+ return -EIO;
+ }
+
+ preempt_disable();
+ WRITE_ONCE(sema[0], i);
+ wmb();
+ while (!READ_ONCE(cb.seen))
+ cpu_relax();
+
+ elapsed[i - 1] = ENGINE_READ_FW(ce->engine, RING_TIMESTAMP);
+ preempt_enable();
+ }
+
+ for (i = 0; i < ARRAY_SIZE(elapsed); i++)
+ elapsed[i] = (sema[i + 1] - elapsed[i]) << COUNT;
+
+ cycles = trifilter(elapsed);
+ pr_info("%s: completion latency %d cycles, %lluns\n",
+ ce->engine->name, cycles >> COUNT,
+ cycles_to_ns(ce->engine, cycles));
+
+ return intel_gt_wait_for_idle(ce->engine->gt, HZ);
+}
+
+static void rps_pin(struct intel_gt *gt)
+{
+ /* Pin the frequency to max */
+ atomic_inc(>->rps.num_waiters);
+ intel_uncore_forcewake_get(gt->uncore, FORCEWAKE_ALL);
+
+ mutex_lock(>->rps.lock);
+ intel_rps_set(>->rps, gt->rps.max_freq);
+ mutex_unlock(>->rps.lock);
+}
+
+static void rps_unpin(struct intel_gt *gt)
+{
+ intel_uncore_forcewake_put(gt->uncore, FORCEWAKE_ALL);
+ atomic_dec(>->rps.num_waiters);
+}
+
+static unsigned long engine_heartbeat_disable(struct intel_engine_cs *engine)
+{
+ unsigned long old;
+
+ old = fetch_and_zero(&engine->props.heartbeat_interval_ms);
+
+ intel_engine_pm_get(engine);
+ intel_engine_park_heartbeat(engine);
+
+ return old;
+}
+
+static void engine_heartbeat_enable(struct intel_engine_cs *engine,
+ unsigned long saved)
+{
+ intel_engine_pm_put(engine);
+
+ engine->props.heartbeat_interval_ms = saved;
+}
+
+static int perf_request_latency(void *arg)
+{
+ struct drm_i915_private *i915 = arg;
+ struct intel_engine_cs *engine;
+ struct pm_qos_request qos;
+ int err = 0;
+
+ if (INTEL_GEN(i915) < 8) /* per-engine CS timestamp, semaphores */
+ return 0;
+
+ cpu_latency_qos_add_request(&qos, 0); /* disable cstates */
+
+ for_each_uabi_engine(engine, i915) {
+ unsigned long saved_heartbeat;
+ struct intel_context *ce;
+
+ ce = intel_context_create(engine);
+ if (IS_ERR(ce))
+ goto out;
+
+ err = intel_context_pin(ce);
+ if (err) {
+ intel_context_put(ce);
+ goto out;
+ }
+
+ saved_heartbeat = engine_heartbeat_disable(engine);
+ rps_pin(engine->gt);
+
+ if (err == 0)
+ err = measure_semaphore_response(ce);
+ if (err == 0)
+ err = measure_idle_dispatch(ce);
+ if (err == 0)
+ err = measure_busy_dispatch(ce);
+ if (err == 0)
+ err = measure_inter_request(ce);
+ if (err == 0)
+ err = measure_context_switch(ce);
+ if (err == 0)
+ err = measure_completion(ce);
+
+ rps_unpin(engine->gt);
+ engine_heartbeat_enable(engine, saved_heartbeat);
+
+ intel_context_unpin(ce);
+ intel_context_put(ce);
+ if (err)
+ goto out;
+ }
+
+out:
+ if (igt_flush_test(i915))
+ err = -EIO;
+
+ cpu_latency_qos_remove_request(&qos);
+ return err;
+}
+
static int s_sync0(void *arg)
{
struct perf_series *ps = arg;
@@ -2042,6 +2653,7 @@ static int perf_parallel_engines(void *arg)
int i915_request_perf_selftests(struct drm_i915_private *i915)
{
static const struct i915_subtest tests[] = {
+ SUBTEST(perf_request_latency),
SUBTEST(perf_series_engines),
SUBTEST(perf_parallel_engines),
};
--
2.20.1
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