On Wed, May 27, 2020 at 2:50 PM Arnd Bergmann <[email protected]> wrote: > > On Wed, May 27, 2020 at 2:35 PM Sedat Dilek <[email protected]> wrote: > > On Wed, May 27, 2020 at 2:31 PM Arnd Bergmann <[email protected]> wrote: > > > On Wed, May 27, 2020 at 1:36 PM Sedat Dilek <[email protected]> wrote: > > > > On Wed, May 27, 2020 at 1:27 PM Arnd Bergmann <[email protected]> wrote: > > > > > On Wed, May 27, 2020 at 12:33 PM Marco Elver <[email protected]> wrote: > > > > > > > > > > This gives us back 80% of the performance drop on clang, and 50% > > > > > of the drop I saw with gcc, compared to current mainline. > > > > > > > > > > Tested-by: Arnd Bergmann <[email protected]> > > > > > > > > > > > > > Hi Arnd, > > > > > > > > with "mainline" you mean Linux-next aka Linux v5.8 - not v5.7? > > > > > > I meant v5.7. > > > > > > > I have not seen __unqual_scalar_typeof(x) in compiler_types.h in Linux > > > > v5.7. > > > > > > > > Is there a speedup benefit also for Linux v5.7? > > > > Which patches do I need? > > > > > > v5.7-rc is the baseline and is the fastest I currently see. On certain > > > files, > > > I saw an intermittent 10x slowdown that was already fixed earlier, now > > > linux-next > > > is more like 2x slowdown for me and 1.2x with this patch on top, so we're > > > almost back to the speed of linux-5.7. > > > > > > > Which clang version did you use - and have you set KCSAN kconfigs - > > AFAICS this needs clang-11? > > I'm currently using clang-11, but I see the same problem with older > versions, and both with and without KCSAN enabled. I think the issue > is mostly the deep nesting of macros that leads to code bloat. >
Thanks. With clang-10: $ scripts/diffconfig /boot/config-5.7.0-rc7-2-amd64-clang .config BUILD_SALT "5.7.0-rc7-2-amd64-clang" -> "5.7.0-rc7-3-amd64-clang" +HAVE_ARCH_KCSAN y With clang-11: $ scripts/diffconfig /boot/config-5.7.0-rc7-2-amd64-clang .config BUILD_SALT "5.7.0-rc7-2-amd64-clang" -> "5.7.0-rc7-3-amd64-clang" CLANG_VERSION 100001 -> 110000 +CC_HAS_ASM_INLINE y +HAVE_ARCH_KCSAN y +HAVE_KCSAN_COMPILER y +KCSAN n Which KCSAN kconfigs did you enable? - Sedat -
