I think you are missing the point. This series doesn't pin threads to cores. It pins threads to one L3, which can have 4 or 8 cores.
Marek On Thu, Sep 6, 2018 at 5:22 AM, Axel Davy <davyax...@gmail.com> wrote: > Hi Marek, > > Shouldn't this core pinning be handled by the kernel ? > > Else all multithreaded games (or applications) need an update. > > I also see a risk in applications handling the core pinning: several > intensive applications > may pin the same cores. The kernel would be able to switch automatically > the pinned cores if load would be better shared among cores. > > Yours, > > Axel Davy > > > On 9/6/18 6:02 AM, Marek Olšák wrote: >> >> Hi, >> >> When the Ryzen CPUs were launched, they didn't perform very well in >> games, and it took a while before games were patched. Guess what, >> Mesa drivers have suffered from the same inefficincies until now. >> >> The AMD Zen architecture has multiple core complexes (CCX) where each >> CCX has e.g. 4C/8T and always one L3 cache. If application and driver >> threads don't run on the same CCX, communication between threads is >> slow, because multiple L3 caches must maintain coherency between them. >> Atomic operations seem to suffer the most, almost as if they were >> uncached. (are they?) >> >> This series pins the application thread and all driver execution >> threads to 1 L3 cache (1 CCX). If the application thread is already >> pinned to a hw thread or core(s), all driver threads are pinned to >> the same L3 cache (CCX) as the application thread. >> >> Shader compiler threads are unpinned, as they are not critical. >> >> The piglit/drawoverhead microbenchmark shows that this increases >> performance by 32% for DrawElements and 25% for DrawArrays on Ryzen >> 1st-Gen CPUs. It will probably be much less with real apps. >> >> Please review. >> >> Thanks, >> Marek >> _______________________________________________ >> mesa-dev mailing list >> mesa-dev@lists.freedesktop.org >> https://lists.freedesktop.org/mailman/listinfo/mesa-dev > > > _______________________________________________ mesa-dev mailing list mesa-dev@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/mesa-dev
