autonuma: reduce cache footprint when scanning page tables
authorHuang Ying <ying.huang@intel.com>
Sun, 1 Dec 2019 01:57:32 +0000 (17:57 -0800)
committerLinus Torvalds <torvalds@linux-foundation.org>
Sun, 1 Dec 2019 20:59:09 +0000 (12:59 -0800)
commita818f5363a0eba04bcff986c64c919d3f44b8017
treefc05add8627a44fe3082cfe47933f9c2a096bb3a
parentbfe9d006c971a5daefe7a8b27819ccd497090fd8
autonuma: reduce cache footprint when scanning page tables

In auto NUMA balancing page table scanning, if the pte_protnone() is
true, the PTE needs not to be changed because it's in target state
already.  So other checking on corresponding struct page is unnecessary
too.

So, if we check pte_protnone() firstly for each PTE, we can avoid
unnecessary struct page accessing, so that reduce the cache footprint of
NUMA balancing page table scanning.

In the performance test of pmbench memory accessing benchmark with 80:20
read/write ratio and normal access address distribution on a 2 socket
Intel server with Optance DC Persistent Memory, perf profiling shows
that the autonuma page table scanning time reduces from 1.23% to 0.97%
(that is, reduced 21%) with the patch.

Link: http://lkml.kernel.org/r/20191101075727.26683-3-ying.huang@intel.com
Signed-off-by: "Huang, Ying" <ying.huang@intel.com>
Acked-by: Mel Gorman <mgorman@suse.de>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
mm/mprotect.c