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authorH.J. Lu <hjl.tools@gmail.com>2017-06-02 17:32:21 -0700
committerH.J. Lu <hjl.tools@gmail.com>2017-06-02 17:32:37 -0700
commit808fd9e6fe23f96078d4e297de1131117d3898bb (patch)
tree76336f1f7937cfd45db787e7b659a77da655ba26 /sysdeps
parent3e6def237a5681387b27ac55298b3ab25a054dbf (diff)
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x86: Update __x86_shared_non_temporal_threshold
__x86_shared_non_temporal_threshold was set to 6 times of per-core
shared cache size, based on the large memcpy micro benchmark in glibc
on a 8-core processor.  For a processor with more than 8 cores, the
threshold is too low.  Set __x86_shared_non_temporal_threshold to the
3/4 of the total shared cache size so that it is unchanged on 8-core
processors.  On processors with less than 8 cores, the threshold is
lower.

	* sysdeps/x86/cacheinfo.c (__x86_shared_non_temporal_threshold):
	Set to the 3/4 of the total shared cache size.
Diffstat (limited to 'sysdeps')
-rw-r--r--sysdeps/x86/cacheinfo.c6
1 files changed, 4 insertions, 2 deletions
diff --git a/sysdeps/x86/cacheinfo.c b/sysdeps/x86/cacheinfo.c
index 12ffeef5b5..f66f2b86e0 100644
--- a/sysdeps/x86/cacheinfo.c
+++ b/sysdeps/x86/cacheinfo.c
@@ -767,8 +767,10 @@ intel_bug_no_cache_info:
 
   /* 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;
+     store becomes faster on a 8-core processor.  This is the 3/4 of the
+     total shared cache size.  */
+  __x86_shared_non_temporal_threshold
+    = __x86_shared_cache_size * threads * 3 / 4;
 }
 
 #endif