0a5f4e5b45
When freeing a batch of pages from Per-CPU-Pages(PCP) back to buddy, the zone->lock is held and then pages are chosen from PCP's migratetype list. While there is actually no need to do this 'choose part' under lock since it's PCP pages, the only CPU that can touch them is us and irq is also disabled. Moving this part outside could reduce lock held time and improve performance. Test with will-it-scale/page_fault1 full load: kernel Broadwell(2S) Skylake(2S) Broadwell(4S) Skylake(4S) v4.16-rc2+ 9034215 7971818 13667135 15677465 this patch 9536374 +5.6% 8314710 +4.3% 14070408 +3.0% 16675866 +6.4% What the test does is: starts $nr_cpu processes and each will repeatedly do the following for 5 minutes: - mmap 128M anonymouse space - write access to that space - munmap. The score is the aggregated iteration. https://github.com/antonblanchard/will-it-scale/blob/master/tests/page_fault1.c Link: http://lkml.kernel.org/r/20180301062845.26038-3-aaron.lu@intel.com Signed-off-by: Aaron Lu <aaron.lu@intel.com> Acked-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Cc: Andi Kleen <ak@linux.intel.com> Cc: Dave Hansen <dave.hansen@intel.com> Cc: David Rientjes <rientjes@google.com> Cc: Huang Ying <ying.huang@intel.com> Cc: Kemi Wang <kemi.wang@intel.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Tim Chen <tim.c.chen@linux.intel.com> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
See Documentation/00-INDEX for a list of what is contained in each file.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.