Re: [Intel-gfx] [RFC 0/5] Per-client engine stats
On 15/02/2018 09:47, Chris Wilson wrote: Quoting Tvrtko Ursulin (2018-02-15 09:44:58) On 14/02/2018 19:20, Chris Wilson wrote: Quoting Tvrtko Ursulin (2018-02-14 18:50:30) From: Tvrtko Ursulin Another re-post of my earlier, now slightly updated work, to expose a DRM client hierarchy in sysfs in order to enable a top like tool: So what I don't like about it is that it is a new interface in sysfs. We already have a PMU interface for statistics and would rather see that extended than abandoned. If perf can handle new processes coming and going, surely we can handle new clients? :| I don't think it means abandoning the PMU, just that I don't see it suitable for this use case. Even if we go with adding a PMU task mode, that is a separate thing from this. It would allow profiling of a single task, but not enumerating and profiling all clients/tasks from perf/PMU. I think perf top seems to handle processes coming and going, so I don't think it's a fundamental limitation of perf, just our understanding :) I'd rather have one interface to maintain :) Referencing my old branch when I barely started on per-task PMU, I think that the idea was to add another i915 PMU instance which allows events with tasks contexts. Then in the implementation we would something like i915_get_engine_busy_for_task(event->ctx->task). This would work for "perf stat -e i915/rcs0-busy some-program". But not for perf top - that one actually creates sampling counters which need to provide things like PIDs and call-chains on each sample and I don't see that we can ever do this. Ignoring "perf top", we could implement a top like tool using the above described new per-task PMU, but with two limitations: 1. No per-client support - only per-task. 2. More overhead - need a data structure, plus it's management, to map from tasks to lists of drm clients etc. My point is that I did not see the sysfs interface as a substantial additional burden. Apart from the sysfs management bits, the rest is actually building blocks for per-task PMU. Because the solution from point 2 above would still need to aggregate the per-client stats, after it is able to walk per-task clients. Regards, Tvrtko ___ Intel-gfx mailing list Intel-gfx@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/intel-gfx
Re: [Intel-gfx] [RFC 0/5] Per-client engine stats
Quoting Tvrtko Ursulin (2018-02-15 09:44:58) > > On 14/02/2018 19:20, Chris Wilson wrote: > > Quoting Tvrtko Ursulin (2018-02-14 18:50:30) > >> From: Tvrtko Ursulin > >> > >> Another re-post of my earlier, now slightly updated work, to expose a DRM > >> client > >> hierarchy in sysfs in order to enable a top like tool: > > > > So what I don't like about it is that it is a new interface in sysfs. We > > already have a PMU interface for statistics and would rather see that > > extended than abandoned. If perf can handle new processes coming and > > going, surely we can handle new clients? :| > > I don't think it means abandoning the PMU, just that I don't see it > suitable for this use case. > > Even if we go with adding a PMU task mode, that is a separate thing from > this. It would allow profiling of a single task, but not enumerating and > profiling all clients/tasks from perf/PMU. I think perf top seems to handle processes coming and going, so I don't think it's a fundamental limitation of perf, just our understanding :) I'd rather have one interface to maintain :) -Chris ___ Intel-gfx mailing list Intel-gfx@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/intel-gfx
Re: [Intel-gfx] [RFC 0/5] Per-client engine stats
On 14/02/2018 19:20, Chris Wilson wrote: Quoting Tvrtko Ursulin (2018-02-14 18:50:30) From: Tvrtko Ursulin Another re-post of my earlier, now slightly updated work, to expose a DRM client hierarchy in sysfs in order to enable a top like tool: So what I don't like about it is that it is a new interface in sysfs. We already have a PMU interface for statistics and would rather see that extended than abandoned. If perf can handle new processes coming and going, surely we can handle new clients? :| I don't think it means abandoning the PMU, just that I don't see it suitable for this use case. Even if we go with adding a PMU task mode, that is a separate thing from this. It would allow profiling of a single task, but not enumerating and profiling all clients/tasks from perf/PMU. Regards, Tvrtko ___ Intel-gfx mailing list Intel-gfx@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/intel-gfx
Re: [Intel-gfx] [RFC 0/5] Per-client engine stats
Quoting Tvrtko Ursulin (2018-02-14 18:50:30) > From: Tvrtko Ursulin > > Another re-post of my earlier, now slightly updated work, to expose a DRM > client > hierarchy in sysfs in order to enable a top like tool: So what I don't like about it is that it is a new interface in sysfs. We already have a PMU interface for statistics and would rather see that extended than abandoned. If perf can handle new processes coming and going, surely we can handle new clients? :| -Chris ___ Intel-gfx mailing list Intel-gfx@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/intel-gfx
