public inbox for glibc-cvs@sourceware.org help / color / mirror / Atom feed
From: Adhemerval Zanella <azanella@sourceware.org> To: glibc-cvs@sourceware.org Subject: [glibc/azanella/bz30944-memcpy-zen] x86: Do not prefer ERMS for memset on Zen3+ Date: Fri, 27 Oct 2023 12:30:03 +0000 (GMT) [thread overview] Message-ID: <20231027123003.0D46C3853508@sourceware.org> (raw) https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=4c023248ca791eefec5a7553057c0af3b9035f6c commit 4c023248ca791eefec5a7553057c0af3b9035f6c Author: Adhemerval Zanella <adhemerval.zanella@linaro.org> Date: Fri Oct 27 00:08:15 2023 -0300 x86: Do not prefer ERMS for memset on Zen3+ The REP STOSB usage on memset does show any performance gain on Zen3/Zen4 cores compared to the vectorized loops. Checked on x86_64-linux-gnu. Diff: --- sysdeps/x86/dl-cacheinfo.h | 16 +++++++++++----- 1 file changed, 11 insertions(+), 5 deletions(-) diff --git a/sysdeps/x86/dl-cacheinfo.h b/sysdeps/x86/dl-cacheinfo.h index 546ff0725a..f5fd7b2566 100644 --- a/sysdeps/x86/dl-cacheinfo.h +++ b/sysdeps/x86/dl-cacheinfo.h @@ -1010,11 +1010,17 @@ dl_init_cacheinfo (struct cpu_features *cpu_features) if (tunable_size > minimum_rep_movsb_threshold) rep_movsb_threshold = tunable_size; - /* NB: The default value of the x86_rep_stosb_threshold tunable is the - same as the default value of __x86_rep_stosb_threshold and the - minimum value is fixed. */ - rep_stosb_threshold = TUNABLE_GET (x86_rep_stosb_threshold, - long int, NULL); + /* For AMD Zen3+ architecture, the performance of vectorized loop is + slight better than ERMS. */ + if (cpu_features->basic.kind == arch_kind_amd) + rep_stosb_threshold = SIZE_MAX; + + if (TUNABLE_IS_INITIALIZED (x86_rep_stosb_threshold)) + /* NB: The default value of the x86_rep_stosb_threshold tunable is the + same as the default value of __x86_rep_stosb_threshold and the + minimum value is fixed. */ + rep_stosb_threshold = TUNABLE_GET (x86_rep_stosb_threshold, + long int, NULL); TUNABLE_SET_WITH_BOUNDS (x86_data_cache_size, data, 0, SIZE_MAX); TUNABLE_SET_WITH_BOUNDS (x86_shared_cache_size, shared, 0, SIZE_MAX);
reply other threads:[~2023-10-27 12:30 UTC|newest] Thread overview: [no followups] expand[flat|nested] mbox.gz Atom feed
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=20231027123003.0D46C3853508@sourceware.org \ --to=azanella@sourceware.org \ --cc=glibc-cvs@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).