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From: "cvs-commit at gcc dot gnu.org" <sourceware-bugzilla@sourceware.org> To: glibc-bugs@sourceware.org Subject: [Bug string/30994] REP MOVSB performance suffers from page aliasing on Zen 4 Date: Thu, 04 Apr 2024 10:36:35 +0000 [thread overview] Message-ID: <bug-30994-131-fDs2nfCmr7@http.sourceware.org/bugzilla/> (raw) In-Reply-To: <bug-30994-131@http.sourceware.org/bugzilla/> https://sourceware.org/bugzilla/show_bug.cgi?id=30994 --- Comment #14 from Sourceware Commits <cvs-commit at gcc dot gnu.org> --- The release/2.39/master branch has been updated by Arjun Shankar <arjun@sourceware.org>: https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=aa4249266e9906c4bc833e4847f4d8feef59504f commit aa4249266e9906c4bc833e4847f4d8feef59504f Author: Adhemerval Zanella <adhemerval.zanella@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.tools@gmail.com> (cherry picked from commit 0c0d39fe4aeb0f69b26e76337c5dfd5530d5d44e) -- You are receiving this mail because: You are on the CC list for the bug.
prev parent reply other threads:[~2024-04-04 10:36 UTC|newest] Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top 2023-10-24 6:18 [Bug string/30994] New: " bmerry at sarao dot ac.za 2023-10-24 6:19 ` [Bug string/30994] " bmerry at sarao dot ac.za 2023-10-24 6:20 ` bmerry at sarao dot ac.za 2023-10-24 6:21 ` bmerry at sarao dot ac.za 2023-10-24 6:21 ` bmerry at sarao dot ac.za 2023-10-24 6:32 ` bmerry at sarao dot ac.za 2023-10-24 17:57 ` sam at gentoo dot org 2023-10-25 12:40 ` fweimer at redhat dot com 2023-10-25 13:37 ` bmerry at sarao dot ac.za 2023-10-27 12:39 ` adhemerval.zanella at linaro dot org 2023-10-27 13:04 ` bmerry at sarao dot ac.za 2023-10-27 13:16 ` bmerry at sarao dot ac.za 2023-10-30 8:21 ` bmerry at sarao dot ac.za 2023-10-30 13:30 ` adhemerval.zanella at linaro dot org 2023-10-30 14:21 ` bmerry at sarao dot ac.za 2023-10-30 16:27 ` adhemerval.zanella at linaro dot org 2023-11-07 15:44 ` jamborm at gcc dot gnu.org 2023-11-29 3:08 ` lilydjwg at gmail dot com 2023-11-29 13:01 ` holger@applied-asynchrony.com 2023-11-29 15:57 ` jrmuizel at gmail dot com 2023-11-29 17:25 ` gabravier at gmail dot com 2023-11-29 17:30 ` sam at gentoo dot org 2023-11-29 19:58 ` matti.niemenmaa+sourcesbugs at iki dot fi 2023-11-29 21:08 ` pageexec at gmail dot com 2023-11-30 3:13 ` dushistov at mail dot ru 2023-12-08 8:32 ` mati865 at gmail dot com 2024-02-13 16:54 ` cvs-commit at gcc dot gnu.org 2024-04-04 10:36 ` cvs-commit at gcc dot gnu.org [this message]
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