[Intel-gfx] [PATCH i-g-t v4] benchmarks/gem_wsim: Command submission workload simulator

[Tvrtko Ursulin]

On 20/04/2017 15:23, Chris Wilson wrote:
> On Thu, Apr 20, 2017 at 01:29:11PM +0100, Tvrtko Ursulin wrote:
>> +static void
>> +alloc_step_batch(struct workload *wrk, struct w_step *w, struct w_step_eb *b,
>> +		 enum intel_engine_id engine, unsigned int flags)
>> +{
>> +	unsigned int bb_i, j = 0;
>> +
>> +	b->obj[j].handle = gem_create(fd, 4096);
>> +	b->obj[j].flags = EXEC_OBJECT_WRITE;
>> +	j++;
>> +
>> +	if (flags & SEQNO) {
>> +		b->obj[j].handle = wrk->status_page_handle;
>> +		j++;
>> +	}
>> +
>> +	bb_i = j++;
>> +	b->bb_sz = get_bb_sz(w->duration.max);
>> +	b->bb_handle = b->obj[bb_i].handle = gem_create(fd, b->bb_sz);
>> +	terminate_bb(w, b, engine, flags);
>> +
>> +	igt_assert(w->dependency <= 0);
>> +	if (w->dependency) {
>> +		int dep_idx = w->idx + w->dependency;
>> +
>> +		igt_assert(dep_idx >= 0 && dep_idx < wrk->nr_steps);
>> +		igt_assert(wrk->steps[dep_idx].type == BATCH);
>> +
>> +		b->obj[j].handle = b->obj[bb_i].handle;
>> +		bb_i = j;
>> +		b->obj[j - 1].handle = wrk->steps[dep_idx].b[0].obj[0].handle;
>> +		j++;
>> +
>> +		if (wrk->steps[dep_idx].b[1].obj[0].handle) {
>> +			b->obj[j].handle = b->obj[bb_i].handle;
>> +			bb_i = j;
>> +			b->obj[j - 1].handle =
>> +					wrk->steps[dep_idx].b[1].obj[0].handle;
>> +			j++;
>> +		}
>> +	}
>> +
>> +	if (flags & SEQNO) {
>> +		b->reloc.presumed_offset = -1;
>
> So as I understand it, you are caching the execbuf/obj/reloc for the
> workload and then may reissue later with different seqno on different
> rings? In which case we have a problem as the kernel will write back the >
 >
> updated offsets to b->reloc.presumed_offset and b->obj[].offset and in
> future passes they will match and the seqno write will go into the wrong
> slot (if it swaps rings).
>
> You either want to reset presumed_offset=-1 each time, or better for all
> concerned write the correct address alongside the seqno (which also
> enables NORELOC).
>
> Delta incoming.

Only the seqno changes, but each engine has its own eb/obj/reloc. So I 
think there is no problem. Or is there still?

Regards,

Tvrtko