lkml.org 
[lkml]   [2008]   [Feb]   [27]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: [RFC][PATCH] page reclaim throttle take2
    On Tue, 26 Feb 2008 23:19:08 -0800 (PST)
    David Rientjes <rientjes@google.com> wrote:
    > My suggestion is merely to make the number of concurrent page reclaim
    > threads be a function of how many online cpus there are. Threads can
    > easily be added or removed for cpu hotplug events by callback functions.
    >
    > That's different than allowing users to change the number of threads with
    > yet another sysctl. Unless there are situations that can be presented
    > where tuning the number of threads is advantageous to reduce lock
    > contention, for example, and not simply working around other VM problems,
    > then I see no point for an additional sysctl.
    >
    > So my suggestion is to implement this in terms of
    > CONFIG_NUM_RECLAIM_THREADS_PER_CPU and add callback functions for cpu
    > hotplug events that add or remove this number of threads.
    >

    Hmm, but kswapd, which is main worker of page reclaiming, is per-node.
    And reclaim is done based on zone.
    per-zone/per-node throttling seems to make sense.

    I know his environment has 4cpus per node but throttle to 3 was the best
    number in his measurement. Then it seems num-per-cpu is excessive.
    (At least, ratio(%) is better.)
    When zone-reclaiming is improved to be scale well, we'll have to change
    this throttle.

    BTW, could someone try his patch on x86_64/ppc ?
    I'd like to see how contention is heavy on other machines.

    Thanks,
    -kame




    \
     
     \ /
      Last update: 2008-02-27 08:57    [W:0.021 / U:94.188 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site