[Intel-gfx] [PATCH 08/10] drm/i915: Expose per-engine client busyness

[Chris Wilson]

Quoting Tvrtko Ursulin (2020-03-18 14:15:31)
> 
> On 18/03/2020 14:00, Chris Wilson wrote:
> > Quoting Tvrtko Ursulin (2020-03-18 12:11:37)
> >> +static u64
> >> +pphwsp_busy_add(struct i915_gem_context *ctx, unsigned int class)
> >> +{
> >> +       struct i915_gem_engines *engines = rcu_dereference(ctx->engines);
> >> +       struct i915_gem_engines_iter it;
> >> +       struct intel_context *ce;
> >> +       u64 total = 0;
> >> +
> >> +       for_each_gem_engine(ce, engines, it) {
> >> +               if (ce->engine->uabi_class == class)
> >> +                       total += ce->runtime.total;
> >> +       }
> >> +
> >> +       return total;
> >> +}
> >> +
> >> +static ssize_t
> >> +show_client_busy(struct device *kdev, struct device_attribute *attr, char *buf)
> >> +{
> >> +       struct i915_engine_busy_attribute *i915_attr =
> >> +               container_of(attr, typeof(*i915_attr), attr);
> >> +       unsigned int class = i915_attr->engine_class;
> >> +       struct i915_drm_client *client = i915_attr->client;
> >> +       u64 total = atomic64_read(&client->past_runtime[class]);
> >> +       struct list_head *list = &client->ctx_list;
> >> +       struct i915_gem_context *ctx;
> >> +
> >> +       rcu_read_lock();
> >> +       list_for_each_entry_rcu(ctx, list, client_link) {
> >> +               total += atomic64_read(&ctx->past_runtime[class]);
> >> +               total += pphwsp_busy_add(ctx, class);
> > 
> > Hmm. I would like to have some GEM context agnosticism here. At the
> > moment, all I have to offer is
> > 
> > struct client_runtime {
> >       struct list_head client_link;
> >       atomic64_t past_runtime;
> >       u64 (*cur_runtime)(struct client_runtime *);
> > };
> 
> What exactly do you mean here? Who keeps a list and of what and what 
> does the vfunc do?

This is what you've added to GEM context. Here in i915/i915_drm_client.c
we shouldn't have to know about i915/gem/i915_gem_context internals. So
the GEM context registers its client_runtime (by coupling that into the
list).
-Chris