This is a note to let you know that I've just added the patch titled
s390/mm: have 16 byte aligned struct pages
to the 3.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
s390-mm-have-16-byte-aligned-struct-pages.patch
and it can be found in the queue-3.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <[email protected]> know about it.
>From 4bffbb3455372a26816e364fb4448810f7014452 Mon Sep 17 00:00:00 2001
From: Heiko Carstens <[email protected]>
Date: Thu, 8 Nov 2012 14:18:47 +0100
Subject: s390/mm: have 16 byte aligned struct pages
From: Heiko Carstens <[email protected]>
commit 4bffbb3455372a26816e364fb4448810f7014452 upstream.
Select HAVE_ALIGNED_STRUCT_PAGE on s390, so that the slub allocator can make
use of compare and swap double for lockless updates. This increases the size
of struct page to 64 bytes (instead of 56 bytes), however the performance gain
justifies the increased size:
- now excactly four struct pages fit into a single cache line; the
case that accessing a struct page causes two cache line loads
does not exist anymore.
- calculating the offset of a struct page within the memmap array
is only a simple shift instead of a more expensive multiplication.
A "hackbench 200 process 200" run on a 32 cpu system did show an 8% runtime
improvement.
Signed-off-by: Heiko Carstens <[email protected]>
Signed-off-by: Martin Schwidefsky <[email protected]>
Signed-off-by: CAI Qian <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
arch/s390/Kconfig | 1 +
1 file changed, 1 insertion(+)
--- a/arch/s390/Kconfig
+++ b/arch/s390/Kconfig
@@ -93,6 +93,7 @@ config S390
select ARCH_SAVE_PAGE_KEYS if HIBERNATION
select HAVE_MEMBLOCK
select HAVE_MEMBLOCK_NODE_MAP
+ select HAVE_ALIGNED_STRUCT_PAGE if SLUB
select ARCH_DISCARD_MEMBLOCK
select ARCH_INLINE_SPIN_TRYLOCK
select ARCH_INLINE_SPIN_TRYLOCK_BH
Patches currently in stable-queue which might be from [email protected]
are
queue-3.4/s390-mm-have-16-byte-aligned-struct-pages.patch
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