Re: [PATCH i-g-t 1/3] benchmarks/gem_syslatency: Pass a write hazard around

[Mika Kuoppala <mika.kuoppala@linux.intel.com>]

Chris Wilson <chris@chris-wilson.co.uk> writes:

> Extend the i915 load to (optionally) pass a write hazard between
> engines, causing us to wait on the interrupt between engines. Thus
> adding MI_USER_INTERRUPT irq handling to our list of sins.


Is it the eb_move_to_gpu waiting then for the object
due to write?

..and this then arming the interrupts later down the
chain?

-Mika

>
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
> ---
>  benchmarks/gem_syslatency.c | 28 ++++++++++++++++++----------
>  1 file changed, 18 insertions(+), 10 deletions(-)
>
> diff --git a/benchmarks/gem_syslatency.c b/benchmarks/gem_syslatency.c
> index de59eaf82..9160e2199 100644
> --- a/benchmarks/gem_syslatency.c
> +++ b/benchmarks/gem_syslatency.c
> @@ -53,6 +53,7 @@ struct gem_busyspin {
>  	pthread_t thread;
>  	unsigned long count;
>  	bool leak;
> +	bool interrupts;
>  };
>  
>  struct sys_wait {
> @@ -94,7 +95,7 @@ static void *gem_busyspin(void *arg)
>  	const uint32_t bbe = MI_BATCH_BUFFER_END;
>  	struct gem_busyspin *bs = arg;
>  	struct drm_i915_gem_execbuffer2 execbuf;
> -	struct drm_i915_gem_exec_object2 obj;
> +	struct drm_i915_gem_exec_object2 obj[2];
>  	const unsigned sz = bs->leak ? 16 << 20 : 4 << 10;
>  	unsigned engines[16];
>  	unsigned nengine;
> @@ -107,13 +108,15 @@ static void *gem_busyspin(void *arg)
>  	for_each_engine(fd, engine)
>  		if (!ignore_engine(fd, engine)) engines[nengine++] = engine;
>  
> -	memset(&obj, 0, sizeof(obj));
> -	obj.handle = gem_create(fd, sz);
> -	gem_write(fd, obj.handle, 0, &bbe, sizeof(bbe));
> +	memset(obj, 0, sizeof(obj));
> +	obj[0].handle = gem_create(fd, 4096);
> +	obj[0].flags = EXEC_OBJECT_WRITE;
> +	obj[1].handle = gem_create(fd, sz);
> +	gem_write(fd, obj[1].handle, 0, &bbe, sizeof(bbe));
>  
>  	memset(&execbuf, 0, sizeof(execbuf));
> -	execbuf.buffers_ptr = (uintptr_t)&obj;
> -	execbuf.buffer_count = 1;
> +	execbuf.buffers_ptr = (uintptr_t)(obj + !bs->interrupts);
> +	execbuf.buffer_count = 1 + !!bs->interrupts;
>  	execbuf.flags |= LOCAL_I915_EXEC_HANDLE_LUT;
>  	execbuf.flags |= LOCAL_I915_EXEC_NO_RELOC;
>  	if (__gem_execbuf(fd, &execbuf)) {
> @@ -129,9 +132,9 @@ static void *gem_busyspin(void *arg)
>  		}
>  		bs->count += nengine;
>  		if (bs->leak) {
> -			gem_madvise(fd, obj.handle, I915_MADV_DONTNEED);
> -			obj.handle = gem_create(fd, sz);
> -			gem_write(fd, obj.handle, 0, &bbe, sizeof(bbe));
> +			gem_madvise(fd, obj[1].handle, I915_MADV_DONTNEED);
> +			obj[1].handle = gem_create(fd, sz);
> +			gem_write(fd, obj[1].handle, 0, &bbe, sizeof(bbe));
>  		}
>  	}
>  
> @@ -305,13 +308,17 @@ int main(int argc, char **argv)
>  	int field = -1;
>  	int enable_gem_sysbusy = 1;
>  	bool leak = false;
> +	bool interrupts = false;
>  	int n, c;
>  
> -	while ((c = getopt(argc, argv, "t:f:bmn")) != -1) {
> +	while ((c = getopt(argc, argv, "t:f:bmni")) != -1) {
>  		switch (c) {
>  		case 'n': /* dry run, measure baseline system latency */
>  			enable_gem_sysbusy = 0;
>  			break;
> +		case 'i': /* interrupts ahoy! */
> +			interrupts = true;
> +			break;
>  		case 't':
>  			/* How long to run the benchmark for (seconds) */
>  			time = atoi(optarg);
> @@ -346,6 +353,7 @@ int main(int argc, char **argv)
>  		for (n = 0; n < ncpus; n++) {
>  			bind_cpu(&attr, n);
>  			busy[n].leak = leak;
> +			busy[n].interrupts = interrupts;
>  			pthread_create(&busy[n].thread, &attr,
>  				       gem_busyspin, &busy[n]);
>  		}
> -- 
> 2.17.0
>
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