From 34679d7eac9ecc20face093db9aa610f1e9c893a Mon Sep 17 00:00:00 2001 From: Shaohua Li <shaohua.li@intel.com> Date: Tue, 24 May 2011 17:11:18 -0700 Subject: [PATCH] mmap: add alignment for some variables Make some variables have correct alignment/section to avoid cache issue. In a workload which heavily does mmap/munmap, the variables will be used frequently. Signed-off-by: Shaohua Li <shaohua.li@intel.com> Cc: Andi Kleen <andi@firstfloor.org> Cc: Rik van Riel <riel@redhat.com> Cc: Hugh Dickins <hughd@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> --- mm/mmap.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) diff --git a/mm/mmap.c b/mm/mmap.c index 772140c53ab1..eaec3df82a2b 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -84,10 +84,14 @@ pgprot_t vm_get_page_prot(unsigned long vm_flags) } EXPORT_SYMBOL(vm_get_page_prot); -int sysctl_overcommit_memory = OVERCOMMIT_GUESS; /* heuristic overcommit */ -int sysctl_overcommit_ratio = 50; /* default is 50% */ +int sysctl_overcommit_memory __read_mostly = OVERCOMMIT_GUESS; /* heuristic overcommit */ +int sysctl_overcommit_ratio __read_mostly = 50; /* default is 50% */ int sysctl_max_map_count __read_mostly = DEFAULT_MAX_MAP_COUNT; -struct percpu_counter vm_committed_as; +/* + * Make sure vm_committed_as in one cacheline and not cacheline shared with + * other variables. It can be updated by several CPUs frequently. + */ +struct percpu_counter vm_committed_as ____cacheline_aligned_in_smp; /* * Check that a process has enough memory to allocate a new virtual -- 2.34.1