From: "H.J. Lu" <hjl.tools@gmail.com>
To: libc-alpha@sourceware.org
Subject: [PATCH] x86: Don't set Prefer_No_AVX512 for processors with AVX512 and AVX-VNNI
Date: Sun, 5 Dec 2021 19:23:03 -0800 [thread overview]
Message-ID: <20211206032303.7159-1-hjl.tools@gmail.com> (raw)
Don't set Prefer_No_AVX512 on processors with AVX512 and AVX-VNNI since
they won't lower CPU frequency when ZMM load and store instructions are
used.
---
sysdeps/x86/cpu-features.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)
diff --git a/sysdeps/x86/cpu-features.c b/sysdeps/x86/cpu-features.c
index be2498b2e7..311ade1f26 100644
--- a/sysdeps/x86/cpu-features.c
+++ b/sysdeps/x86/cpu-features.c
@@ -538,8 +538,11 @@ init_cpu_features (struct cpu_features *cpu_features)
|= bit_arch_Prefer_No_VZEROUPPER;
else
{
- cpu_features->preferred[index_arch_Prefer_No_AVX512]
- |= bit_arch_Prefer_No_AVX512;
+ /* Processors with AVX512 and AVX-VNNI won't lower CPU frequency
+ when ZMM load and store instructions are used. */
+ if (!CPU_FEATURES_CPU_P (cpu_features, AVX_VNNI))
+ cpu_features->preferred[index_arch_Prefer_No_AVX512]
+ |= bit_arch_Prefer_No_AVX512;
/* Avoid RTM abort triggered by VZEROUPPER inside a
transactionally executing RTM region. */
--
2.33.1
next reply other threads:[~2021-12-06 3:23 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-12-06 3:23 H.J. Lu [this message]
2021-12-07 7:47 ` Noah Goldstein
2021-12-07 12:53 ` H.J. Lu
2021-12-07 13:17 ` Arjan van de Ven
2021-12-07 13:34 ` H.J. Lu
2021-12-07 14:05 ` Florian Weimer
2021-12-07 14:15 ` H.J. Lu
2021-12-07 15:47 ` Florian Weimer
2021-12-07 15:52 ` H.J. Lu
2021-12-07 16:22 ` Thiago Macieira
2021-12-07 19:32 ` Noah Goldstein
2022-04-23 1:51 ` Sunil Pandey
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