fbertsch helpfully wrote a query that breaks down physical cores into the % with and without HT enabled: https://sql.telemetry.mozilla.org/queries/47219/source >From this we can see that, e.g., 6.7% of systems that report "2 logical cores" (and ~2% of all systems) actually only have 1 physical core with 2 hyperthreads. This seemed like the worst case for heuristics that solely talk about logical threads (which, with only 1 exception that I can see [1], seems like most of our heuristics).
That SQL query came out of a more general request to report logical and physical info in the dashboard: https://github.com/mozilla/firefox-hardware-report/issues/60 If enough people are regularly interested in this data, it'd be good to bump the priority of that issue. Cheers, Luke [1] https://searchfox.org/mozilla-central/source/gfx/layers/PaintThread.cpp#132 On Wed, Mar 28, 2018 at 2:03 PM, Steve Fink <sf...@mozilla.com> wrote: > Yes, sorry, a couple of people pointed that out to me privately. And I did > get that mixed up; I was assuming processors, despite the page specifically > pointing out "physical cores". > > I still think there's something to be kept in mind here, though. Even with > 4 processors (2 hyperthreaded cores or whatever), it's never correct to > assume that running something on a different thread is a gold bullet for > performance problems. I'm all for increasing the concurrency of our code as > long as we ensure that it doesn't hurt in the case of low levels of actual > parallelism. > > What that means in practice, I'm not entirely sure, but it does seem like > we should be more conscious about thread priorities and global thread pool > management. Also, lock contention is a real thing. It has been coming up > here and there and wiping out parallelization gains. > > > On 3/28/18 10:27 AM, Ben Kelly wrote: > >> That page says "physical cores", so its not taking into account hyper >> threading, right? So even a high end macbook pro falls in that category? >> >> On Tue, Mar 27, 2018 at 5:02 PM, Mike Conley <mcon...@mozilla.com >> <mailto:mcon...@mozilla.com>> wrote: >> >> Thanks for drawing attention to this, sfink. >> >> This is likely to become more important as we continue to scale up our >> parallelization with content processes and threads. >> >> On 21 March 2018 at 14:54, Steve Fink <sf...@mozilla.com >> <mailto:sf...@mozilla.com>> wrote: >> >> > Just to drive home a point, let's play a game. >> > >> > First, guesstimate what percentage of our users have systems >> with 2 or >> > fewer cores. >> > >> > Then visit >> https://hardware.metrics.mozilla.com/#goto-cpu-and-memory >> <https://hardware.metrics.mozilla.com/#goto-cpu-and-memory> to >> > check your guess. >> > >> > (I didn't say it was a *fun* game.) >> > >> > >> > _______________________________________________ >> > dev-platform mailing list >> > dev-platform@lists.mozilla.org >> <mailto:dev-platform@lists.mozilla.org> >> > https://lists.mozilla.org/listinfo/dev-platform >> <https://lists.mozilla.org/listinfo/dev-platform> >> > >> _______________________________________________ >> dev-platform mailing list >> dev-platform@lists.mozilla.org <mailto:dev-platform@lists.mozilla.org >> > >> https://lists.mozilla.org/listinfo/dev-platform >> <https://lists.mozilla.org/listinfo/dev-platform> >> >> >> > _______________________________________________ > dev-platform mailing list > dev-platform@lists.mozilla.org > https://lists.mozilla.org/listinfo/dev-platform > _______________________________________________ dev-platform mailing list dev-platform@lists.mozilla.org https://lists.mozilla.org/listinfo/dev-platform
