On Thu, Dec 06, 2012 at 04:59:04PM -0800, Greg Kroah-Hartman wrote: > 3.6-stable review patch. If anyone has any objections, please let me know. > > ------------------ > > From: Heiko Carstens <heiko.carst...@de.ibm.com> > > 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 <heiko.carst...@de.ibm.com> > Signed-off-by: Martin Schwidefsky <schwidef...@de.ibm.com> > Signed-off-by: CAI Qian <caiq...@redhat.com> > Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>
Same as for 3.4: compare and swap double is not available for 3.6 on s390. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
