lkml.org 
[lkml]   [2013]   [Dec]   [13]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH 1/7] mm: page_alloc: exclude unreclaimable allocations from zone fairness policy
On 12/13/2013 09:10 AM, Mel Gorman wrote:
> From: Johannes Weiner <hannes@cmpxchg.org>
>
> Dave Hansen noted a regression in a microbenchmark that loops around
> open() and close() on an 8-node NUMA machine and bisected it down to
> 81c0a2bb515f ("mm: page_alloc: fair zone allocator policy"). That
> change forces the slab allocations of the file descriptor to spread
> out to all 8 nodes, causing remote references in the page allocator
> and slab.
>
> The round-robin policy is only there to provide fairness among memory
> allocations that are reclaimed involuntarily based on pressure in each
> zone. It does not make sense to apply it to unreclaimable kernel
> allocations that are freed manually, in this case instantly after the
> allocation, and incur the remote reference costs twice for no reason.
>
> Only round-robin allocations that are usually freed through page
> reclaim or slab shrinking.
>
> Cc: <stable@kernel.org>
> Bisected-by: Dave Hansen <dave.hansen@intel.com>
> Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
> Signed-off-by: Mel Gorman <mgorman@suse.de>

Reviewed-by: Rik van Riel <riel@redhat.com>

--
All rights reversed


\
 
 \ /
  Last update: 2013-12-13 18:21    [W:0.227 / U:0.044 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site