From: H.J. Lu Date: Mon, 6 Dec 2021 15:14:12 +0000 (-0800) Subject: x86: Don't set Prefer_No_AVX512 for processors with AVX512 and AVX-VNNI X-Git-Tag: glibc-2.35~285 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=ceeffe968c01b1202e482f4855cb6baf5c6cb713;p=thirdparty%2Fglibc.git x86: Don't set Prefer_No_AVX512 for processors with AVX512 and AVX-VNNI 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. --- diff --git a/sysdeps/x86/cpu-features.c b/sysdeps/x86/cpu-features.c index be2498b2e7c..311ade1f263 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. */