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| author | Noah Goldstein <goldstein.w.n@gmail.com> | 2024-05-24 12:38:51 -0500 |
|---|---|---|
| committer | Noah Goldstein <goldstein.w.n@gmail.com> | 2024-05-30 12:36:09 -0500 |
| commit | 46b5e98ef6f1b9f4b53851f152ecb8209064b26c (patch) | |
| tree | f3008f5bbe51de418ade2aeb13363408c7ba2536 /manual | |
| parent | 5bf0ab80573d66e4ae5d94b094659094336da90f (diff) | |
| download | glibc-46b5e98ef6f1b9f4b53851f152ecb8209064b26c.zip glibc-46b5e98ef6f1b9f4b53851f152ecb8209064b26c.tar.gz glibc-46b5e98ef6f1b9f4b53851f152ecb8209064b26c.tar.bz2 | |
x86: Add seperate non-temporal tunable for memset
The tuning for non-temporal stores for memset vs memcpy is not always
the same. This includes both the exact value and whether non-temporal
stores are profitable at all for a given arch.
This patch add `x86_memset_non_temporal_threshold`. Currently we
disable non-temporal stores for non Intel vendors as the only
benchmarks showing its benefit have been on Intel hardware.
Reviewed-by: H.J. Lu <hjl.tools@gmail.com>
Diffstat (limited to 'manual')
| -rw-r--r-- | manual/tunables.texi | 16 |
1 files changed, 15 insertions, 1 deletions
diff --git a/manual/tunables.texi b/manual/tunables.texi index baaf751..8dd02d8 100644 --- a/manual/tunables.texi +++ b/manual/tunables.texi @@ -52,6 +52,7 @@ glibc.elision.skip_lock_busy: 3 (min: 0, max: 2147483647) glibc.malloc.top_pad: 0x20000 (min: 0x0, max: 0xffffffffffffffff) glibc.cpu.x86_rep_stosb_threshold: 0x800 (min: 0x1, max: 0xffffffffffffffff) glibc.cpu.x86_non_temporal_threshold: 0xc0000 (min: 0x4040, max: 0xfffffffffffffff) +glibc.cpu.x86_memset_non_temporal_threshold: 0xc0000 (min: 0x4040, max: 0xfffffffffffffff) glibc.cpu.x86_shstk: glibc.pthread.stack_cache_size: 0x2800000 (min: 0x0, max: 0xffffffffffffffff) glibc.cpu.hwcap_mask: 0x6 (min: 0x0, max: 0xffffffffffffffff) @@ -495,7 +496,8 @@ thread stack originally backup by Huge Pages to default pages. @cindex shared_cache_size tunables @cindex tunables, shared_cache_size @cindex non_temporal_threshold tunables -@cindex tunables, non_temporal_threshold +@cindex memset_non_temporal_threshold tunables +@cindex tunables, non_temporal_threshold, memset_non_temporal_threshold @deftp {Tunable namespace} glibc.cpu Behavior of @theglibc{} can be tuned to assume specific hardware capabilities @@ -574,6 +576,18 @@ like memmove and memcpy. This tunable is specific to i386 and x86-64. @end deftp +@deftp Tunable glibc.cpu.x86_memset_non_temporal_threshold +The @code{glibc.cpu.x86_memset_non_temporal_threshold} tunable allows +the user to set threshold in bytes for non temporal store in +memset. Non temporal stores give a hint to the hardware to move data +directly to memory without displacing other data from the cache. This +tunable is used by some platforms to determine when to use non +temporal stores memset. + +This tunable is specific to i386 and x86-64. +@end deftp + + @deftp Tunable glibc.cpu.x86_rep_movsb_threshold The @code{glibc.cpu.x86_rep_movsb_threshold} tunable allows the user to set threshold in bytes to start using "rep movsb". The value must be |