Chris Wilson <ch...@chris-wilson.co.uk> writes:
> Start our preparations for guaranteeing endless execution.
>
> First, we just want to estimate the 'ulta-low latency' dispatch overhead
> by running an endless chain of batch buffers. The legacy binding process
> here will be replaced by async VM_BIND, but for the moment this
> suffices to construct the GTT as required for arbitrary
> *user-controlled* indirect execution.
>
> Signed-off-by: Chris Wilson <ch...@chris-wilson.co.uk>
> Cc: Joonas Lahtinen <joonas.lahti...@linux.intel.com>
> Cc: Mika Kuoppala <mika.kuopp...@linux.intel.com>
> ---
> lib/igt_core.h | 1 +
> tests/Makefile.sources | 3 +
> tests/i915/gem_exec_endless.c | 354 ++++++++++++++++++++++++++++++++++
> tests/meson.build | 1 +
> 4 files changed, 359 insertions(+)
> create mode 100644 tests/i915/gem_exec_endless.c
>
> diff --git a/lib/igt_core.h b/lib/igt_core.h
> index b97fa2faa..c58715204 100644
> --- a/lib/igt_core.h
> +++ b/lib/igt_core.h
> @@ -1369,6 +1369,7 @@ void igt_kmsg(const char *format, ...);
> #define KMSG_DEBUG "<7>[IGT] "
>
> #define READ_ONCE(x) (*(volatile typeof(x) *)(&(x)))
> +#define WRITE_ONCE(x, v) do *(volatile typeof(x) *)(&(x)) = (v); while (0)
>
> #define MSEC_PER_SEC (1000)
> #define USEC_PER_SEC (1000*MSEC_PER_SEC)
> diff --git a/tests/Makefile.sources b/tests/Makefile.sources
> index c450fa0ed..d1f7cf819 100644
> --- a/tests/Makefile.sources
> +++ b/tests/Makefile.sources
> @@ -265,6 +265,9 @@ gem_exec_schedule_SOURCES = i915/gem_exec_schedule.c
> TESTS_progs += gem_exec_store
> gem_exec_store_SOURCES = i915/gem_exec_store.c
>
> +TESTS_progs += gem_exec_endless
> +gem_exec_endless_SOURCES = i915/gem_exec_endless.c
> +
> TESTS_progs += gem_exec_suspend
> gem_exec_suspend_SOURCES = i915/gem_exec_suspend.c
>
> diff --git a/tests/i915/gem_exec_endless.c b/tests/i915/gem_exec_endless.c
> new file mode 100644
> index 000000000..c25c94641
> --- /dev/null
> +++ b/tests/i915/gem_exec_endless.c
> @@ -0,0 +1,354 @@
> +/*
> + * Copyright © 2019 Intel Corporation
> + *
> + * Permission is hereby granted, free of charge, to any person obtaining a
> + * copy of this software and associated documentation files (the "Software"),
> + * to deal in the Software without restriction, including without limitation
> + * the rights to use, copy, modify, merge, publish, distribute, sublicense,
> + * and/or sell copies of the Software, and to permit persons to whom the
> + * Software is furnished to do so, subject to the following conditions:
> + *
> + * The above copyright notice and this permission notice (including the next
> + * paragraph) shall be included in all copies or substantial portions of the
> + * Software.
> + *
> + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
> + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
> + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
> + * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
> + * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
> + * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
> DEALINGS
> + * IN THE SOFTWARE.
> + */
> +
> +#include <sys/ioctl.h>
> +
> +#include "i915/gem.h"
> +#include "i915/gem_ring.h"
> +#include "igt.h"
> +#include "sw_sync.h"
> +
> +#define MAX_ENGINES 64
> +
> +#define MI_SEMAPHORE_WAIT (0x1c << 23)
> +#define MI_SEMAPHORE_POLL (1 << 15)
> +#define MI_SEMAPHORE_SAD_GT_SDD (0 << 12)
> +#define MI_SEMAPHORE_SAD_GTE_SDD (1 << 12)
> +#define MI_SEMAPHORE_SAD_LT_SDD (2 << 12)
> +#define MI_SEMAPHORE_SAD_LTE_SDD (3 << 12)
> +#define MI_SEMAPHORE_SAD_EQ_SDD (4 << 12)
> +#define MI_SEMAPHORE_SAD_NEQ_SDD (5 << 12)
> +
> +static uint32_t batch_create(int i915)
> +{
> + const uint32_t bbe = MI_BATCH_BUFFER_END;
> + uint32_t handle = gem_create(i915, 4096);
> + gem_write(i915, handle, 0, &bbe, sizeof(bbe));
> + return handle;
> +}
> +
> +struct supervisor {
> + int device;
> + uint32_t handle;
> + uint32_t context;
> +
> + uint32_t *map;
> + uint32_t *semaphore;
> + uint32_t *terminate;
> + uint64_t *dispatch;
> +};
> +
> +static unsigned int offset_in_page(void *addr)
> +{
> + return (uintptr_t)addr & 4095;
> +}
> +
> +static uint32_t __supervisor_create_context(int i915,
> + const struct
> intel_execution_engine2 *e)
> +{
> + I915_DEFINE_CONTEXT_PARAM_ENGINES(engines, 2);
> + struct drm_i915_gem_context_create_ext_setparam p_ring = {
> + {
> + .name = I915_CONTEXT_CREATE_EXT_SETPARAM,
> + .next_extension = 0
> + },
> + {
> + .param = I915_CONTEXT_PARAM_RINGSIZE,
> + .value = 4096,
> + },
> + };
> + struct drm_i915_gem_context_create_ext_setparam p_engines = {
> + {
> + .name = I915_CONTEXT_CREATE_EXT_SETPARAM,
> + .next_extension = to_user_pointer(&p_ring)
> +
> + },
> + {
> + .param = I915_CONTEXT_PARAM_ENGINES,
> + .value = to_user_pointer(&engines),
> + .size = sizeof(engines),
> + },
> + };
> + struct drm_i915_gem_context_create_ext_setparam p_persistence = {
> + {
> + .name = I915_CONTEXT_CREATE_EXT_SETPARAM,
> + .next_extension = to_user_pointer(&p_engines)
> +
> + },
> + {
> + .param = I915_CONTEXT_PARAM_PERSISTENCE,
> + .value = 0
> + },
> + };
> + struct drm_i915_gem_context_create_ext create = {
> + .flags = I915_CONTEXT_CREATE_FLAGS_USE_EXTENSIONS,
> + .extensions = to_user_pointer(&p_persistence),
> + };
> +
> + for (int n = 0; n < 2; n++) { /* [exec, bind] */
> + engines.engines[n].engine_class = e->class;
> + engines.engines[n].engine_instance = e->instance;
> + }
> +
> + ioctl(i915, DRM_IOCTL_I915_GEM_CONTEXT_CREATE_EXT, &create);
> + return create.ctx_id;
> +}
> +
> +static void __supervisor_create(int i915,
> + const struct intel_execution_engine2 *e,
> + struct supervisor *sv)
> +{
> + sv->device = i915;
> + sv->context = __supervisor_create_context(i915, e);
> + igt_require(sv->context);
> +
> + sv->handle = gem_create(i915, 4096);
> + sv->map = gem_mmap__device_coherent(i915, sv->handle,
> + 0, 4096, PROT_WRITE);
> +}
> +
> +static void __supervisor_run(struct supervisor *sv)
> +{
> + struct drm_i915_gem_exec_object2 obj = {
> + .handle = sv->handle,
> + .flags = EXEC_OBJECT_PINNED
> + };
> + struct drm_i915_gem_execbuffer2 execbuf = {
> + .buffers_ptr = to_user_pointer(&obj),
> + .buffer_count = 1,
> + .rsvd1 = sv->context,
> + };
> + uint32_t *cs = sv->map;
> +
> + sv->semaphore = cs + 1000;
> +
> + *cs++ = MI_SEMAPHORE_WAIT |
> + MI_SEMAPHORE_POLL |
> + MI_SEMAPHORE_SAD_EQ_SDD |
> + (4 - 2);
> + *cs++ = 1;
> + *cs++ = offset_in_page(sv->semaphore);
> + *cs++ = 0;
> +
> + sv->terminate = cs;
> + *cs++ = MI_STORE_DWORD_IMM;
> + *cs++ = offset_in_page(sv->semaphore);
> + *cs++ = 0;
> + *cs++ = 0;
> +
> + *cs++ = MI_BATCH_BUFFER_START | 1 << 8 | 1;
> + sv->dispatch = (uint64_t *)cs; /* to be filled in later */
> +
> + gem_execbuf(sv->device, &execbuf);
> + igt_assert_eq_u64(obj.offset, 0);
> +}
> +
> +static void supervisor_open(int i915,
> + const struct intel_execution_engine2 *e,
> + struct supervisor *sv)
> +{
> + __supervisor_create(i915, e, sv);
> + __supervisor_run(sv);
> +}
> +
> +static void supervisor_dispatch(struct supervisor *sv, uint64_t addr)
> +{
> + WRITE_ONCE(*sv->dispatch, 64 << 10);
addr << 10 ?
-Mika
> + WRITE_ONCE(*sv->semaphore, 1);
> + __sync_synchronize();
> +}
> +
> +static void legacy_supervisor_bind(struct supervisor *sv, uint32_t handle,
> uint64_t addr)
> +{
> + struct drm_i915_gem_exec_object2 obj[2] = {
> + {
> + .handle = handle,
> + .offset = addr,
> + .flags = EXEC_OBJECT_PINNED
> + },
> + {
> + .handle = batch_create(sv->device)
> + }
> + };
> + struct drm_i915_gem_execbuffer2 execbuf = {
> + .buffers_ptr = to_user_pointer(obj),
> + .buffer_count = ARRAY_SIZE(obj),
> + .rsvd1 = sv->context,
> + .flags = 1, /* legacy bind engine */
> + };
> +
> + gem_execbuf(sv->device, &execbuf);
> + gem_close(sv->device, obj[1].handle);
> +
> + gem_sync(sv->device, handle); /* must wait for async binds */
> +}
> +
> +static void emit_bbe_chain(uint32_t *cs)
> +{
> + *cs++ = MI_BATCH_BUFFER_START | 1 << 8 | 1;
> + *cs++ = 0;
> + *cs++ = 0;
> +}
> +
> +static void supervisor_close(struct supervisor *sv)
> +{
> + WRITE_ONCE(*sv->terminate, MI_BATCH_BUFFER_END);
> + WRITE_ONCE(*sv->semaphore, 1);
> + __sync_synchronize();
> + munmap(sv->map, 4096);
> +
> + gem_sync(sv->device, sv->handle);
> + gem_close(sv->device, sv->handle);
> +
> + gem_context_destroy(sv->device, sv->context);
> +}
> +
> +static int read_timestamp_frequency(int i915)
> +{
> + int value = 0;
> + drm_i915_getparam_t gp = {
> + .value = &value,
> + .param = I915_PARAM_CS_TIMESTAMP_FREQUENCY,
> + };
> + ioctl(i915, DRM_IOCTL_I915_GETPARAM, &gp);
> + return value;
> +}
> +
> +static int cmp_u32(const void *A, const void *B)
> +{
> + const uint32_t *a = A, *b = B;
> +
> + if (*a < *b)
> + return -1;
> + else if (*a > *b)
> + return 1;
> + else
> + return 0;
> +}
> +
> +static uint32_t trifilter(uint32_t *x)
> +{
> + qsort(x, 5, sizeof(*x), cmp_u32);
> + return (x[1] + 2 * x[2] + x[3]) / 4;
> +}
> +
> +#define TIMESTAMP (0x358)
> +static void endless_dispatch(int i915, const struct intel_execution_engine2
> *e)
> +{
> + const uint32_t mmio_base = gem_engine_mmio_base(i915, e->name);
> + const int cs_timestamp_freq = read_timestamp_frequency(i915);
> + uint32_t handle, *cs, *map;
> + struct supervisor sv;
> + uint32_t latency[5];
> + uint32_t *timestamp;
> + uint32_t *result;
> +
> + /*
> + * Launch a supervisor bb.
> + * Wait on semaphore.
> + * Bind second bb.
> + * Write new address into MI_BB_START
> + * Release semaphore.
> + *
> + * Check we see the second bb execute.
> + *
> + * Chain MI_BB_START to supervisor bb (replacing BBE).
> + *
> + * Final dispatch is BBE.
> + */
> +
> + igt_require(gem_class_has_mutable_submission(i915, e->class));
> +
> + igt_require(mmio_base);
> + timestamp = (void *)igt_global_mmio + mmio_base + TIMESTAMP;
> +
> + supervisor_open(i915, e, &sv);
> + result = sv.semaphore + 1;
> +
> + handle = gem_create(i915, 4096);
> + cs = map = gem_mmap__device_coherent(i915, handle, 0, 4096, PROT_WRITE);
> + *cs++ = 0x24 << 23 | 2; /* SRM */
> + *cs++ = mmio_base + TIMESTAMP;
> + *cs++ = offset_in_page(result);
> + *cs++ = 0;
> + emit_bbe_chain(cs);
> + munmap(map, 4096);
> + legacy_supervisor_bind(&sv, handle, 64 << 10);
> +
> + for (int pass = 0; pass < ARRAY_SIZE(latency); pass++) {
> + uint32_t start, end;
> +
> + WRITE_ONCE(*result, 0);
> + start = READ_ONCE(*timestamp);
> + supervisor_dispatch(&sv, 64 << 10);
> + while (!(end = READ_ONCE(*result)))
> + ;
> +
> + igt_assert_eq(READ_ONCE(*sv.semaphore), 0);
> + latency[pass] = end - start;
> + }
> +
> + latency[0] = trifilter(latency);
> + igt_info("Dispatch latency: %u cycles, %.0fns\n",
> + latency[0], latency[0] * 1e9 / cs_timestamp_freq);
> +
> + supervisor_close(&sv);
> +
> + gem_close(i915, handle);
> +}
> +
> +#define test_each_engine(T, i915, e) \
> + igt_subtest_with_dynamic(T) __for_each_physical_engine(i915, e) \
> + for_each_if(gem_class_can_store_dword(i915, (e)->class)) \
> + igt_dynamic_f("%s", (e)->name)
> +igt_main
> +{
> + const struct intel_execution_engine2 *e;
> + int i915 = -1;
> +
> + igt_skip_on_simulation();
> +
> + igt_fixture {
> + i915 = drm_open_driver(DRIVER_INTEL);
> + igt_require_gem(i915);
> + }
> +
> + igt_subtest_group {
> + struct intel_mmio_data mmio;
> +
> + igt_fixture {
> + igt_require(gem_scheduler_enabled(i915));
> + igt_require(gem_scheduler_has_preemption(i915));
> +
> + intel_register_access_init(&mmio,
> + intel_get_pci_device(),
> + false, i915);
> + }
> +
> + test_each_engine("dispatch", i915, e)
> + endless_dispatch(i915, e);
> +
> + igt_fixture
> + intel_register_access_fini(&mmio);
> + }
> +}
> diff --git a/tests/meson.build b/tests/meson.build
> index 88e4875b6..9312b6944 100644
> --- a/tests/meson.build
> +++ b/tests/meson.build
> @@ -140,6 +140,7 @@ i915_progs = [
> 'gem_exec_big',
> 'gem_exec_capture',
> 'gem_exec_create',
> + 'gem_exec_endless',
> 'gem_exec_fence',
> 'gem_exec_flush',
> 'gem_exec_gttfill',
> --
> 2.26.2
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