public inbox for glibc-bugs@sourceware.org help / color / mirror / Atom feed
From: "bmerry at sarao dot ac.za" <sourceware-bugzilla@sourceware.org> To: glibc-bugs@sourceware.org Subject: [Bug string/30994] REP MOVSB performance suffers from page aliasing on Zen 4 Date: Mon, 30 Oct 2023 08:21:16 +0000 [thread overview] Message-ID: <bug-30994-131-MkHTFLx0mb@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 #9 from Bruce Merry <bmerry at sarao dot ac.za> --- So in those cases, REP MOVSB seems to be a slow-down, but there do also seem to be cases where REP MOVSB is much faster (this is on Zen 4) e.g. $ ./memcpy_loop -D 512 -b 4096 -t mmap_huge -f memcpy -p 10000000 -r 5 0 Using 1 threads, each with 4096 bytes of mmap_huge memory (10000000 passes) Using function memcpy 94.5295 GB/s 94.3382 GB/s 94.474 GB/s 94.2385 GB/s 94.5105 GB/s $ GLIBC_TUNABLES=glibc.cpu.x86_rep_movsb_threshold=1000000 ./memcpy_loop -D 512 -b 4096 -t mmap_huge -f memcpy -p 10000000 -r 5 0 Using 1 threads, each with 4096 bytes of mmap_huge memory (10000000 passes) Using function memcpy 56.5062 GB/s 55.3669 GB/s 56.4723 GB/s 55.857 GB/s 56.5396 GB/s When not using huge pages, the vectorised memcpy hits 115.5 GB/s. I'm seeing a lot of cases on Zen 4 where huge pages actually makes things worse; maybe it's related to hardware prefetch reading past the end of the buffer? -- You are receiving this mail because: You are on the CC list for the bug.
next prev parent reply other threads:[~2023-10-30 8:21 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 [this message] 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
Reply instructions: You may reply publicly to this message via plain-text email using any one of the following methods: * Save the following mbox file, import it into your mail client, and reply-to-all from there: mbox Avoid top-posting and favor interleaved quoting: https://en.wikipedia.org/wiki/Posting_style#Interleaved_style * Reply using the --to, --cc, and --in-reply-to switches of git-send-email(1): git send-email \ --in-reply-to=bug-30994-131-MkHTFLx0mb@http.sourceware.org/bugzilla/ \ --to=sourceware-bugzilla@sourceware.org \ --cc=glibc-bugs@sourceware.org \ /path/to/YOUR_REPLY https://kernel.org/pub/software/scm/git/docs/git-send-email.html * If your mail client supports setting the In-Reply-To header via mailto: links, try the mailto: linkBe sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions for how to clone and mirror all data and code used for this inbox; as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).