On Wed, Aug 23, 2017 at 05:11:23PM -0700, Antonio Argenziano wrote:
> The testcase added here, stimulates this scenario where a high priority
> request is sent while another process keeps submitting requests and
> filling its ringbuffer.
s/stimulates/simulates
You're no longer changing igt/gem_ringfill, please adjust the subject
accordingly.
It would be nice to describe that this test will always fail for now, because of
the struct_mutex contention.
>
> From RFC (Chris):
> - Use two FDs, one for each priority submission.
> - Move from gem_ringfill to gem_exec_schedule.
> - Bound processes to same cpu and wake with signals.
>
> Cc: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
>
> Signed-off-by: Antonio Argenziano <antonio.argenziano@xxxxxxxxx>
> ---
> tests/gem_exec_schedule.c | 113 +++++++++++++++++++++++++++++++++++++++++++++-
> 1 file changed, 112 insertions(+), 1 deletion(-)
>
> diff --git a/tests/gem_exec_schedule.c b/tests/gem_exec_schedule.c
> index f2847863..476626e6 100644
> --- a/tests/gem_exec_schedule.c
> +++ b/tests/gem_exec_schedule.c
> @@ -21,7 +21,12 @@
> * IN THE SOFTWARE.
> */
>
> +#define _GNU_SOURCE
> +#include <sched.h>
> +#include <signal.h>
> +
> #include <sys/poll.h>
> +#include <sys/ioctl.h>
>
> #include "igt.h"
> #include "igt_vgem.h"
> @@ -39,6 +44,15 @@
>
> IGT_TEST_DESCRIPTION("Check that we can control the order of execution");
>
> +static void alarm_handler(int sig)
> +{
> +}
> +
> +static int __execbuf(int fd, struct drm_i915_gem_execbuffer2 *execbuf)
> +{
> + return ioctl(fd, DRM_IOCTL_I915_GEM_EXECBUFFER2, execbuf);
> +}
> +
So... __gem_execbuf?
> static int __ctx_set_priority(int fd, uint32_t ctx, int prio)
> {
> struct local_i915_gem_context_param param;
> @@ -659,6 +673,95 @@ static bool has_scheduler(int fd)
> return has > 0;
> }
>
> +static void bind_to_cpu(int cpu)
> +{
> + const int ncpus = sysconf(_SC_NPROCESSORS_ONLN);
> + cpu_set_t allowed;
> +
> + CPU_ZERO(&allowed);
> + CPU_SET(cpu % ncpus, &allowed);
> + igt_assert(sched_setaffinity(getpid(), sizeof(cpu_set_t), &allowed) == 0);
We need to make sure that the child is not running before parent blocks in the
last execbuf - meaning that we probably want to make the parent (but not the
child) realtime. (see email from Chris)
> +}
> +
> +static void setup_timer(int timeout)
> +{
> + struct itimerval itv;
> + struct sigaction sa = { .sa_handler = alarm_handler };
> +
> + sigaction(SIGALRM, &sa, NULL);
> + itv.it_interval.tv_sec = 0;
> + itv.it_interval.tv_usec = 100;
Using this interval doesn't allow fork to complete on my machine.
But we should probably disable the timer across fork anyway.
> + itv.it_value.tv_sec = 0;
> + itv.it_value.tv_usec = timeout * 1000;
> + setitimer(ITIMER_REAL, &itv, NULL);
> +}
> +
> +/*
> + * This test checks that is possible for a high priority request to trigger a
> + * preemption if another context has filled its ringbuffer.
> + * The aim of the test is to make sure that high priority requests cannot be
> + * stalled by low priority tasks.
> + * */
> +static void preempt_while_ringbuffer_full(int fd, uint32_t engine)
> +{
> + uint32_t hp_fd;
> + uint32_t hp_ctx, lp_ctx;
> + struct drm_i915_gem_exec_object2 obj, hp_obj;
> + struct drm_i915_gem_execbuffer2 execbuf;
> +
> + const unsigned timeout = 10; /*ms*/
> + const uint32_t bbe = MI_BATCH_BUFFER_END;
> +
> + hp_fd = drm_open_driver(DRIVER_INTEL);
Why the extra FD if we're going to use non-default contexts anyway?
> +
> + memset(&execbuf, 0, sizeof(execbuf));
> + memset(&obj, 0, sizeof(obj));
> + memset(&hp_obj, 0, sizeof(hp_obj));
> +
> + lp_ctx = gem_context_create(fd);
> + ctx_set_priority(fd, lp_ctx, -MAX_PRIO);
> +
> + hp_ctx = gem_context_create(hp_fd);
> + ctx_set_priority(hp_fd, hp_ctx, MAX_PRIO);
> +
> + hp_obj.handle = gem_create(fd, 4096);
> + gem_write(fd, hp_obj.handle, 0, &bbe, sizeof(bbe));
> +
> + obj.handle = gem_create(fd, 4096);
> + gem_write(fd, obj.handle, 0, &bbe, sizeof(bbe));
> +
> + execbuf.buffers_ptr = to_user_pointer(&obj);
> + execbuf.flags = engine;
> + execbuf.buffer_count = 1;
> + execbuf.rsvd1 = lp_ctx;
> +
> + /*Stall execution and fill ring*/
Malformed comment.
> + igt_spin_batch_new(fd, lp_ctx, engine, 0);
> +
> + setup_timer(timeout);
> + while (__execbuf(fd, &execbuf) == 0)
> + ;
> +
> + /* steal cpu */
Description of what exactly are we doing here and what we're expecting to
happen would save reader a couple of a-ha! moments.
> + bind_to_cpu(0);
> + igt_fork(child, 1) {
> + /* this child is forced to wait for parent to sleep */
> + execbuf.buffers_ptr = to_user_pointer(&hp_obj);
> + execbuf.rsvd1 = hp_ctx;
> + setup_timer(timeout);
> + if (__execbuf(fd, &execbuf)) {
> + igt_assert_f(0, "Failed High priority submission.\n");
> + igt_terminate_spin_batches();
> + }
> + }
> +
> + /* process sleeps waiting for space to free, releasing child */
> + setup_timer(2*timeout);
> + __execbuf(fd, &execbuf);
> + igt_terminate_spin_batches();
> + igt_waitchildren();
> +}
> +
> igt_main
> {
> const struct intel_execution_engine *e;
> @@ -669,7 +772,7 @@ igt_main
> igt_fixture {
> fd = drm_open_driver_master(DRIVER_INTEL);
> igt_require_gem(fd);
> - gem_require_mmap_wc(fd);
> + //gem_require_mmap_wc(fd);
????
> igt_fork_hang_detector(fd);
> }
>
> @@ -731,6 +834,14 @@ igt_main
> }
> }
>
> + igt_subtest_group {
> + for (e = intel_execution_engines; e->name; e++) {
> + igt_subtest_f("preempt-while-full-%s", e->name) {
gem_require_ring()
We also need to make sure that we're skipping on legacy_ringbuffer
(!enable_execlists). Today that's taken care of by has_scheduler, but that may
not be true in the future.
-Michał
> + preempt_while_ringbuffer_full(fd, e->exec_id | e->flags);
> + }
> + }
> + }
> +
> igt_fixture {
> igt_stop_hang_detector();
> close(fd);
> --
> 2.14.1
>
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