Re: [igt-dev] [PATCH i-g-t 10/16] i915/gem_exec_whisper: Fork all-engine tests one-per-engine

[Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>]

On 08/05/2019 11:09, Chris Wilson wrote:
> Add a new mode for some more stress, submit the all-engines tests
> simultaneously, a stream per engine.
> 
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> ---
>   tests/i915/gem_exec_whisper.c | 27 ++++++++++++++++++++++-----
>   1 file changed, 22 insertions(+), 5 deletions(-)
> 
> diff --git a/tests/i915/gem_exec_whisper.c b/tests/i915/gem_exec_whisper.c
> index d3e0b0ba2..d5afc8119 100644
> --- a/tests/i915/gem_exec_whisper.c
> +++ b/tests/i915/gem_exec_whisper.c
> @@ -88,6 +88,7 @@ static void verify_reloc(int fd, uint32_t handle,
>   #define SYNC 0x40
>   #define PRIORITY 0x80
>   #define QUEUES 0x100
> +#define ALL 0x200
>   
>   struct hang {
>   	struct drm_i915_gem_exec_object2 obj;
> @@ -199,6 +200,7 @@ static void whisper(int fd, unsigned engine, unsigned flags)
>   	uint64_t old_offset;
>   	int i, n, loc;
>   	int debugfs;
> +	int nchild;
>   
>   	if (flags & PRIORITY) {
>   		igt_require(gem_scheduler_enabled(fd));
> @@ -215,6 +217,7 @@ static void whisper(int fd, unsigned engine, unsigned flags)
>   				engines[nengine++] = engine;
>   		}
>   	} else {
> +		igt_assert(!(flags & ALL));
>   		igt_require(gem_has_ring(fd, engine));
>   		igt_require(gem_can_store_dword(fd, engine));
>   		engines[nengine++] = engine;
> @@ -233,11 +236,22 @@ static void whisper(int fd, unsigned engine, unsigned flags)
>   	if (flags & HANG)
>   		init_hang(&hang);
>   
> +	nchild = 1;
> +	if (flags & FORKED)
> +		nchild *= sysconf(_SC_NPROCESSORS_ONLN);
> +	if (flags & ALL)
> +		nchild *= nengine;
> +
>   	intel_detect_and_clear_missed_interrupts(fd);
>   	gpu_power_read(&power, &sample[0]);
> -	igt_fork(child, flags & FORKED ? sysconf(_SC_NPROCESSORS_ONLN) : 1)  {
> +	igt_fork(child, nchild) {
>   		unsigned int pass;
>   
> +		if (flags & ALL) {
> +			engines[0] = engines[child % nengine];

Relying on PIDs being sequential feels fragile but suggesting pipes or 
shared memory would be overkill. How about another loop:

if (flags & ALL) {
	for (i = 0; i < nchild; i++) {
		engines_copy = engines;
		nengines_copy = nengine;
		negines_child = 1;
		engines[0] = engines[i];
		igt_fork(child, 1) {
			...
		}
		
		if (in_parent) {
			engines = engines_copy;
			nengine = nengines_copy;
		} else {
			break;
		}
	}
}

?

Regards,

Tvrtko

> +			nengine = 1;
> +		}
> +
>   		memset(&scratch, 0, sizeof(scratch));
>   		scratch.handle = gem_create(fd, 4096);
>   		scratch.flags = EXEC_OBJECT_WRITE;
> @@ -341,7 +355,7 @@ static void whisper(int fd, unsigned engine, unsigned flags)
>   			igt_until_timeout(150) {
>   				uint64_t offset;
>   
> -				if (!(flags & FORKED))
> +				if (nchild == 1)
>   					write_seqno(debugfs, pass);
>   
>   				if (flags & HANG)
> @@ -382,8 +396,8 @@ static void whisper(int fd, unsigned engine, unsigned flags)
>   
>   				gem_write(fd, batches[1023].handle, loc, &pass, sizeof(pass));
>   				for (n = 1024; --n >= 1; ) {
> +					uint32_t handle[2] = {};
>   					int this_fd = fd;
> -					uint32_t handle[2];
>   
>   					execbuf.buffers_ptr = to_user_pointer(&batches[n-1]);
>   					reloc_migrations += batches[n-1].offset != inter[n].presumed_offset;
> @@ -550,7 +564,7 @@ igt_main
>   		{ "queues-sync", QUEUES | SYNC },
>   		{ NULL }
>   	};
> -	int fd;
> +	int fd = -1;
>   
>   	igt_fixture {
>   		fd = drm_open_driver_master(DRIVER_INTEL);
> @@ -561,9 +575,12 @@ igt_main
>   		igt_fork_hang_detector(fd);
>   	}
>   
> -	for (const struct mode *m = modes; m->name; m++)
> +	for (const struct mode *m = modes; m->name; m++) {
>   		igt_subtest_f("%s", m->name)
>   			whisper(fd, ALL_ENGINES, m->flags);
> +		igt_subtest_f("%s-all", m->name)
> +			whisper(fd, ALL_ENGINES, m->flags | ALL);
> +	}
>   
>   	for (const struct intel_execution_engine *e = intel_execution_engines;
>   	     e->name; e++) {
> 
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