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| author | H.J. Lu <hjl.tools@gmail.com> | 2020-07-06 11:48:09 -0700 |
|---|---|---|
| committer | H.J. Lu <hjl.tools@gmail.com> | 2020-07-06 11:48:42 -0700 |
| commit | 3f4b61a0b8de67ef9f20737919c713ddfc4bd620 (patch) | |
| tree | 521cfbc4f297a2fe5d4fc91e6c30d590f1225027 /sysdeps/x86_64 | |
| parent | 6c010c5dde1735f93cc3a6597cdcc2b482af85f8 (diff) | |
| download | glibc-3f4b61a0b8de67ef9f20737919c713ddfc4bd620.zip glibc-3f4b61a0b8de67ef9f20737919c713ddfc4bd620.tar.gz glibc-3f4b61a0b8de67ef9f20737919c713ddfc4bd620.tar.bz2 | |
x86: Add thresholds for "rep movsb/stosb" to tunables
Add x86_rep_movsb_threshold and x86_rep_stosb_threshold to tunables
to update thresholds for "rep movsb" and "rep stosb" at run-time.
Note that the user specified threshold for "rep movsb" smaller than
the minimum threshold will be ignored.
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
Diffstat (limited to 'sysdeps/x86_64')
| -rw-r--r-- | sysdeps/x86_64/multiarch/memmove-vec-unaligned-erms.S | 16 | ||||
| -rw-r--r-- | sysdeps/x86_64/multiarch/memset-vec-unaligned-erms.S | 12 |
2 files changed, 2 insertions, 26 deletions
diff --git a/sysdeps/x86_64/multiarch/memmove-vec-unaligned-erms.S b/sysdeps/x86_64/multiarch/memmove-vec-unaligned-erms.S index 7495324..bd5dc1a 100644 --- a/sysdeps/x86_64/multiarch/memmove-vec-unaligned-erms.S +++ b/sysdeps/x86_64/multiarch/memmove-vec-unaligned-erms.S @@ -56,17 +56,6 @@ # endif #endif -/* Threshold to use Enhanced REP MOVSB. Since there is overhead to set - up REP MOVSB operation, REP MOVSB isn't faster on short data. The - memcpy micro benchmark in glibc shows that 2KB is the approximate - value above which REP MOVSB becomes faster than SSE2 optimization - on processors with Enhanced REP MOVSB. Since larger register size - can move more data with a single load and store, the threshold is - higher with larger register size. */ -#ifndef REP_MOVSB_THRESHOLD -# define REP_MOVSB_THRESHOLD (2048 * (VEC_SIZE / 16)) -#endif - #ifndef PREFETCH # define PREFETCH(addr) prefetcht0 addr #endif @@ -253,9 +242,6 @@ L(movsb): leaq (%rsi,%rdx), %r9 cmpq %r9, %rdi /* Avoid slow backward REP MOVSB. */ -# if REP_MOVSB_THRESHOLD <= (VEC_SIZE * 8) -# error Unsupported REP_MOVSB_THRESHOLD and VEC_SIZE! -# endif jb L(more_8x_vec_backward) 1: mov %RDX_LP, %RCX_LP @@ -331,7 +317,7 @@ L(between_2_3): #if defined USE_MULTIARCH && IS_IN (libc) L(movsb_more_2x_vec): - cmpq $REP_MOVSB_THRESHOLD, %rdx + cmp __x86_rep_movsb_threshold(%rip), %RDX_LP ja L(movsb) #endif L(more_2x_vec): diff --git a/sysdeps/x86_64/multiarch/memset-vec-unaligned-erms.S b/sysdeps/x86_64/multiarch/memset-vec-unaligned-erms.S index af22997..2bfc95d 100644 --- a/sysdeps/x86_64/multiarch/memset-vec-unaligned-erms.S +++ b/sysdeps/x86_64/multiarch/memset-vec-unaligned-erms.S @@ -58,16 +58,6 @@ # endif #endif -/* Threshold to use Enhanced REP STOSB. Since there is overhead to set - up REP STOSB operation, REP STOSB isn't faster on short data. The - memset micro benchmark in glibc shows that 2KB is the approximate - value above which REP STOSB becomes faster on processors with - Enhanced REP STOSB. Since the stored value is fixed, larger register - size has minimal impact on threshold. */ -#ifndef REP_STOSB_THRESHOLD -# define REP_STOSB_THRESHOLD 2048 -#endif - #ifndef SECTION # error SECTION is not defined! #endif @@ -181,7 +171,7 @@ ENTRY (MEMSET_SYMBOL (__memset, unaligned_erms)) ret L(stosb_more_2x_vec): - cmpq $REP_STOSB_THRESHOLD, %rdx + cmp __x86_rep_stosb_threshold(%rip), %RDX_LP ja L(stosb) #endif L(more_2x_vec): |