Re: [igt-dev] [PATCH i-g-t 14/21] gem_wsim: Engine map load balance command

Tvrtko Ursulin
2019-05-15T11:55:37Z

On 15/05/2019 12:48, Chris Wilson wrote:
> Quoting Tvrtko Ursulin (2019-05-15 12:44:41)
>>
>> On 10/05/2019 14:31, Chris Wilson wrote:
>>> Quoting Tvrtko Ursulin (2019-05-08 13:10:51)
>>>> From: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
>>>>
>>>> A new workload command for enabling a load balanced context map (aka
>>>> Virtual Engine). Example usage:
>>>>
>>>> B.1
>>>>
>>>> This turns on load balancing for context one, assuming it has already been
>>>> configured with an engine map. Only DEFAULT engine specifier can be used
>>>> with load balanced engine maps.
>>>
>>> Restriction makes sense for keeping linenoise^W file format simple.
>>>
>>>> Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
>>>> ---
>>>> @@ -1172,6 +1210,8 @@ prepare_workload(unsigned int id, struct workload *wrk, unsigned int flags)
>>>> if (ctx->engine_map) {
>>>> I915_DEFINE_CONTEXT_PARAM_ENGINES(set_engines,
>>>> ctx->engine_map_count + 1);
>>>> + I915_DEFINE_CONTEXT_ENGINES_LOAD_BALANCE(load_balance,
>>>> + ctx->engine_map_count);
>>>> struct drm_i915_gem_context_param param = {
>>>> .ctx_id = ctx_id,
>>>> .param = I915_CONTEXT_PARAM_ENGINES,
>>>> @@ -1179,7 +1219,25 @@ prepare_workload(unsigned int id, struct workload *wrk, unsigned int flags)
>>>> .value = to_user_pointer(&set_engines),
>>>> };
>>>>
>>>> - set_engines.extensions = 0;
>>>> + if (ctx->wants_balance) {
>>>> + set_engines.extensions =
>>>> + to_user_pointer(&load_balance);
>>>> +
>>>> + memset(&load_balance, 0, sizeof(load_balance));
>>>> + load_balance.base.name =
>>>> + I915_CONTEXT_ENGINES_EXT_LOAD_BALANCE;
>>>> + load_balance.num_siblings =
>>>> + ctx->engine_map_count;
>>>> +
>>>> + for (j = 0; j < ctx->engine_map_count; j++) {
>>>> + load_balance.engines[j].engine_class =
>>>> + I915_ENGINE_CLASS_VIDEO; /* FIXME */
>>>> + load_balance.engines[j].engine_instance =
>>>> + ctx->engine_map[j] - VCS1; /* FIXME */
>>>
>>> Ok, more fallout from fixing ctx->engine_map[] first?
>>
>> Not sure I understand the question.
>
> The proliferation of FIXME, the assumption of CLASS_VIDEO and an
> impedance mismatch between engine_map and class:instance. Basically
> those FIXME raise the question of what do you intend this to look like?

Intention that implicit and explicit engine maps get populated by
available engines.

When "-b i915":

1.VCS.1000.0.0 -> implicit map of available vcs engines

M.1.VCS
B.1 \-> explicit map of available vcs engines

That would support Icelake vcs0+vcs2 SKUs. And explicit engine map wsims
would be more portable, like the original ones were.

Also, I am contemplating using VCS2 in wsim as meaning the 2nd VCS
engine, so logical instances. So:

M.1.VCS1|VCS2 -> also works on both SKL and ICL (two vcs SKUs)
B.1

Regards,

Tvrtko