The patch titled
mmap: add alignment for some variables
has been added to the -mm tree. Its filename is
mmap-add-alignment-for-some-variables.patch
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------------------------------------------------------
Subject: mmap: add alignment for some variables
From: Shaohua Li <shaohua.li@xxxxxxxxx>
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@xxxxxxxxx>
Cc: Andi Kleen <andi@xxxxxxxxxxxxxx>
Cc: Rik van Riel <riel@xxxxxxxxxx>
Cc: Hugh Dickins <hughd@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/mmap.c | 10 +++++++---
1 file changed, 7 insertions(+), 3 deletions(-)
diff -puN mm/mmap.c~mmap-add-alignment-for-some-variables mm/mmap.c
--- a/mm/mmap.c~mmap-add-alignment-for-some-variables
+++ a/mm/mmap.c
@@ -84,10 +84,14 @@ pgprot_t vm_get_page_prot(unsigned long
}
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
_
Patches currently in -mm which might be from shaohua.li@xxxxxxxxx are
origin.patch
mmap-add-alignment-for-some-variables.patch
mmap-avoid-unnecessary-anon_vma-lock.patch
mmap-avoid-merging-cloned-vmas.patch
mm-batch-activate_page-to-reduce-lock-contention.patch
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