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| author | H.J. Lu <hjl.tools@gmail.com> | 2021-07-22 20:26:25 -0700 |
|---|---|---|
| committer | H.J. Lu <hjl.tools@gmail.com> | 2021-07-28 13:23:57 -0700 |
| commit | 91cc803d27bda34919717b496b53cf279e44a922 (patch) | |
| tree | 0a6d0b00a94015f1554b6de690a620600dc7513d /sysdeps/x86/cpu-features.c | |
| parent | c25c32165d8b7c506442fdc0304f7a3a223e1f42 (diff) | |
| download | glibc-91cc803d27bda34919717b496b53cf279e44a922.tar.gz glibc-91cc803d27bda34919717b496b53cf279e44a922.tar.xz glibc-91cc803d27bda34919717b496b53cf279e44a922.zip | |
x86-64: Add Avoid_Short_Distance_REP_MOVSB
commit 3ec5d83d2a237d39e7fd6ef7a0bc8ac4c171a4a5
Author: H.J. Lu <hjl.tools@gmail.com>
Date: Sat Jan 25 14:19:40 2020 -0800
x86-64: Avoid rep movsb with short distance [BZ #27130]
introduced some regressions on Intel processors without Fast Short REP
MOV (FSRM). Add Avoid_Short_Distance_REP_MOVSB to avoid rep movsb with
short distance only on Intel processors with FSRM. bench-memmove-large
on Skylake server shows that cycles of __memmove_evex_unaligned_erms
improves for the following data size:
before after Improvement
length=4127, align1=3, align2=0: 479.38 349.25 27%
length=4223, align1=9, align2=5: 405.62 333.25 18%
length=8223, align1=3, align2=0: 786.12 496.38 37%
length=8319, align1=9, align2=5: 727.50 501.38 31%
length=16415, align1=3, align2=0: 1436.88 840.00 41%
length=16511, align1=9, align2=5: 1375.50 836.38 39%
length=32799, align1=3, align2=0: 2890.00 1860.12 36%
length=32895, align1=9, align2=5: 2891.38 1931.88 33%
Diffstat (limited to 'sysdeps/x86/cpu-features.c')
| -rw-r--r-- | sysdeps/x86/cpu-features.c | 5 |
1 files changed, 5 insertions, 0 deletions
diff --git a/sysdeps/x86/cpu-features.c b/sysdeps/x86/cpu-features.c index 706a172ba9..645bba6314 100644 --- a/sysdeps/x86/cpu-features.c +++ b/sysdeps/x86/cpu-features.c @@ -555,6 +555,11 @@ init_cpu_features (struct cpu_features *cpu_features) cpu_features->preferred[index_arch_Prefer_AVX2_STRCMP] |= bit_arch_Prefer_AVX2_STRCMP; } + + /* Avoid avoid short distance REP MOVSB on processor with FSRM. */ + if (CPU_FEATURES_CPU_P (cpu_features, FSRM)) + cpu_features->preferred[index_arch_Avoid_Short_Distance_REP_MOVSB] + |= bit_arch_Avoid_Short_Distance_REP_MOVSB; } /* This spells out "AuthenticAMD" or "HygonGenuine". */ else if ((ebx == 0x68747541 && ecx == 0x444d4163 && edx == 0x69746e65) |