Check -non_temporal_store in GLIBC_IFUNC
Commit Message
The x86 non-temporal threshold is an approximate value. This patch
checks -non_temporal_store in GLIBC_IFUNC to disable non-temporal store.
* sysdeps/x86/cacheinfo.c (init_cacheinfo): Set
__x86_shared_non_temporal_threshold only if it is not set.
* sysdeps/x86/cpu-features.c (__x86_shared_non_temporal_threshold):
New.
(init_cpu_features): Check -non_temporal_store in GLIBC_IFUNC
to disable non-temporal store.
---
sysdeps/x86/cacheinfo.c | 13 +++++++++----
sysdeps/x86/cpu-features.c | 14 ++++++++++++++
2 files changed, 23 insertions(+), 4 deletions(-)
@@ -762,8 +762,13 @@ intel_bug_no_cache_info:
__x86_shared_cache_size = shared;
}
- /* The large memcpy micro benchmark in glibc shows that 6 times of
- shared cache size is the approximate value above which non-temporal
- store becomes faster. */
- __x86_shared_non_temporal_threshold = __x86_shared_cache_size * 6;
+ /* Set non-temporal threshold to an approximate value if it hasn't
+ been set. */
+ if (__x86_shared_non_temporal_threshold == 0)
+ {
+ /* The large memcpy microbenchmark in glibc shows that 6 times
+ of shared cache size is the approximate value above which
+ non-temporal store becomes faster. */
+ __x86_shared_non_temporal_threshold = __x86_shared_cache_size * 6;
+ }
}
@@ -220,6 +220,8 @@ equal (const char *a, const char *b, size_t len)
break; \
}
+extern long int __x86_shared_non_temporal_threshold attribute_hidden;
+
static inline void
init_cpu_features (struct cpu_features *cpu_features, char **env)
{
@@ -540,6 +542,18 @@ no_cpuid:
CHECK_GLIBC_IFUNC_ARCH_BOTH (Fast_Rep_String, disable);
break;
case 18:
+ if (disable)
+ {
+ if (equal (n, "non_temporal_store",
+ sizeof ("non_temporal_store") - 1))
+ {
+ /* Disable non-temporal store with
+ "-non_temporal_store". */
+ __x86_shared_non_temporal_threshold
+ = (long int) -1;
+ break;
+ }
+ }
CHECK_GLIBC_IFUNC_ARCH_BOTH (Fast_Copy_Backward,
disable);
break;