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authorH.J. Lu <hjl.tools@gmail.com>2017-04-18 14:01:45 -0700
committerH.J. Lu <hjl.tools@gmail.com>2017-04-18 14:01:45 -0700
commit4cb334c4d6249686653137ec273d081371b3672d (patch)
tree0ddce19851595aeccad1caf222c91014f7817de2 /sysdeps/x86/cpu-features.h
parent1c53cb49de6d82d9469ccbd5aa0c55924502bd8b (diff)
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x86: Use AVX2 memcpy/memset on Skylake server [BZ #21396]
On Skylake server, AVX512 load/store instructions in memcpy/memset may lead to lower CPU turbo frequency in certain situations. Use of AVX2 in memcpy/memset has been observed to have improved overall performance in many workloads due to the higher frequency. Since AVX512ER is unique to Xeon Phi, this patch sets Prefer_No_AVX512 if AVX512ER isn't available so that AVX2 versions of memcpy/memset are used on Skylake server. [BZ #21396] * sysdeps/x86/cpu-features.c (init_cpu_features): Set Prefer_No_AVX512 if AVX512ER isn't available. * sysdeps/x86/cpu-features.h (bit_arch_Prefer_No_AVX512): New. (index_arch_Prefer_No_AVX512): Likewise. * sysdeps/x86_64/multiarch/memcpy.S (__new_memcpy): Don't use AVX512 version if Prefer_No_AVX512 is set. * sysdeps/x86_64/multiarch/memcpy_chk.S (__memcpy_chk): Likewise. * sysdeps/x86_64/multiarch/memmove.S (__libc_memmove): Likewise. * sysdeps/x86_64/multiarch/memmove_chk.S (__memmove_chk): Likewise. * sysdeps/x86_64/multiarch/mempcpy.S (__mempcpy): Likewise. * sysdeps/x86_64/multiarch/mempcpy_chk.S (__mempcpy_chk): Likewise. * sysdeps/x86_64/multiarch/memset.S (memset): Likewise. * sysdeps/x86_64/multiarch/memset_chk.S (__memset_chk): Likewise.
Diffstat (limited to 'sysdeps/x86/cpu-features.h')
-rw-r--r--sysdeps/x86/cpu-features.h3
1 files changed, 3 insertions, 0 deletions
diff --git a/sysdeps/x86/cpu-features.h b/sysdeps/x86/cpu-features.h
index 1583d65345..85a39e7d70 100644
--- a/sysdeps/x86/cpu-features.h
+++ b/sysdeps/x86/cpu-features.h
@@ -39,6 +39,7 @@
#define bit_arch_Prefer_ERMS (1 << 19)
#define bit_arch_Use_dl_runtime_resolve_opt (1 << 20)
#define bit_arch_Use_dl_runtime_resolve_slow (1 << 21)
+#define bit_arch_Prefer_No_AVX512 (1 << 22)
/* CPUID Feature flags. */
@@ -118,6 +119,7 @@
# define index_arch_Prefer_ERMS FEATURE_INDEX_1*FEATURE_SIZE
# define index_arch_Use_dl_runtime_resolve_opt FEATURE_INDEX_1*FEATURE_SIZE
# define index_arch_Use_dl_runtime_resolve_slow FEATURE_INDEX_1*FEATURE_SIZE
+# define index_arch_Prefer_No_AVX512 FEATURE_INDEX_1*FEATURE_SIZE
# if defined (_LIBC) && !IS_IN (nonlib)
@@ -302,6 +304,7 @@ extern const struct cpu_features *__get_cpu_features (void)
# define index_arch_Prefer_ERMS FEATURE_INDEX_1
# define index_arch_Use_dl_runtime_resolve_opt FEATURE_INDEX_1
# define index_arch_Use_dl_runtime_resolve_slow FEATURE_INDEX_1
+# define index_arch_Prefer_No_AVX512 FEATURE_INDEX_1
#endif /* !__ASSEMBLER__ */