From 808fd9e6fe23f96078d4e297de1131117d3898bb Mon Sep 17 00:00:00 2001 From: "H.J. Lu" Date: Fri, 2 Jun 2017 17:32:21 -0700 Subject: [PATCH] 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. --- ChangeLog | 5 +++++ sysdeps/x86/cacheinfo.c | 6 ++++-- 2 files changed, 9 insertions(+), 2 deletions(-) diff --git a/ChangeLog b/ChangeLog index 3ac07f0517..a97f09d3da 100644 --- a/ChangeLog +++ b/ChangeLog @@ -1,3 +1,8 @@ +2017-06-02 H.J. Lu + + * 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 * manual/errno.texi: Remove redundant error strings. 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