GNU C Library master sources branch master updated. glibc-2.25-392-g808fd9e

[hjl at sourceware dot org]

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http://sourceware.org/git/gitweb.cgi?p=glibc.git;a=commitdiff;h=808fd9e6fe23f96078d4e297de1131117d3898bb

commit 808fd9e6fe23f96078d4e297de1131117d3898bb
Author: H.J. Lu <hjl.tools@gmail.com>
Date:   Fri Jun 2 17:32:21 2017 -0700

    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.

diff --git a/ChangeLog b/ChangeLog
index 3ac07f0..a97f09d 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+2017-06-02  H.J. Lu  <hongjiu.lu@intel.com>
+
+	* sysdeps/x86/cacheinfo.c (__x86_shared_non_temporal_threshold):
+	Set to the 3/4 of the total shared cache size.
+
 2017-06-02  Rical Jasan  <ricaljasan@pacific.net>
 
 	* manual/errno.texi: Remove redundant error strings.
diff --git a/sysdeps/x86/cacheinfo.c b/sysdeps/x86/cacheinfo.c
index 12ffeef..f66f2b8 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

-----------------------------------------------------------------------

Summary of changes:
 ChangeLog               |    5 +++++
 sysdeps/x86/cacheinfo.c |    6 ++++--
 2 files changed, 9 insertions(+), 2 deletions(-)


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