The release/2.39/master branch has been updated by Arjun Shankar <ar...@sourceware.org>:
https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=aa4249266e9906c4bc833e4847f4d8feef59504f commit aa4249266e9906c4bc833e4847f4d8feef59504f Author: Adhemerval Zanella <adhemerval.zane...@linaro.org> Date: Thu Feb 8 10:08:38 2024 -0300 x86: Fix Zen3/Zen4 ERMS selection (BZ 30994) The REP MOVSB usage on memcpy/memmove does not show much performance improvement on Zen3/Zen4 cores compared to the vectorized loops. Also, as from BZ 30994, if the source is aligned and the destination is not the performance can be 20x slower. The performance difference is noticeable with small buffer sizes, closer to the lower bounds limits when memcpy/memmove starts to use ERMS. The performance of REP MOVSB is similar to vectorized instruction on the size limit (the L2 cache). Also, there is no drawback to multiple cores sharing the cache. Checked on x86_64-linux-gnu on Zen3. Reviewed-by: H.J. Lu <hjl.to...@gmail.com> (cherry picked from commit 0c0d39fe4aeb0f69b26e76337c5dfd5530d5d44e) -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/2030515 Title: Terrible memcpy performance on Zen 3 when using rep movsb To manage notifications about this bug go to: https://bugs.launchpad.net/glibc/+bug/2030515/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
