lkml.org 
[lkml]   [2016]   [Oct]   [13]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    SubjectRe: [RFC PATCH 3/5] mm/page_alloc: stop instantly reusing freed page
    From
    Date
    On 10/13/2016 10:08 AM, js1304@gmail.com wrote:
    > From: Joonsoo Kim <iamjoonsoo.kim@lge.com>
    >
    > Allocation/free pattern is usually sequantial. If they are freed to
    > the buddy list, they can be coalesced. However, we first keep these freed
    > pages at the pcp list and try to reuse them until threshold is reached
    > so we don't have enough chance to get a high order freepage. This reusing
    > would provide us some performance advantages since we don't need to
    > get the zone lock and we don't pay the cost to check buddy merging.
    > But, less fragmentation and more high order freepage would compensate
    > this overhead in other ways. First, we would trigger less direct
    > compaction which has high overhead. And, there are usecases that uses
    > high order page to boost their performance.
    >
    > Instantly resuing freed page seems to provide us computational benefit
    > but the other affects more precious things like as I/O performance and
    > memory consumption so I think that it's a good idea to weight
    > later advantage more.

    Again, there's also cache hotness to consider. And whether the
    sequential pattern is still real on a system with higher uptime. Should
    be possible to evaluate with tracepoints?


    \
     
     \ /
      Last update: 2016-10-13 13:15    [W:4.814 / U:0.016 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site