lkml.org 
[lkml]   [2009]   [May]   [1]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: [PATCH] vmscan: evict use-once pages first (v3)
    On Wed, 29 Apr 2009 13:14:36 -0400
    Rik van Riel <riel@redhat.com> wrote:

    > When the file LRU lists are dominated by streaming IO pages,
    > evict those pages first, before considering evicting other
    > pages.
    >
    > This should be safe from deadlocks or performance problems
    > because only three things can happen to an inactive file page:
    > 1) referenced twice and promoted to the active list
    > 2) evicted by the pageout code
    > 3) under IO, after which it will get evicted or promoted
    >
    > The pages freed in this way can either be reused for streaming
    > IO, or allocated for something else. If the pages are used for
    > streaming IO, this pageout pattern continues. Otherwise, we will
    > fall back to the normal pageout pattern.
    >
    > ..
    >
    > +int mem_cgroup_inactive_file_is_low(struct mem_cgroup *memcg)
    > +{
    > + unsigned long active;
    > + unsigned long inactive;
    > +
    > + inactive = mem_cgroup_get_local_zonestat(memcg, LRU_INACTIVE_FILE);
    > + active = mem_cgroup_get_local_zonestat(memcg, LRU_ACTIVE_FILE);
    > +
    > + return (active > inactive);
    > +}

    This function could trivially be made significantly more efficient by
    changing it to do a single pass over all the zones of all the nodes,
    rather than two passes.

    > static unsigned long shrink_list(enum lru_list lru, unsigned long nr_to_scan,
    > struct zone *zone, struct scan_control *sc, int priority)
    > {
    > int file = is_file_lru(lru);
    >
    > - if (lru == LRU_ACTIVE_FILE) {
    > + if (lru == LRU_ACTIVE_FILE && inactive_file_is_low(zone, sc)) {
    > shrink_active_list(nr_to_scan, zone, sc, priority, file);
    > return 0;
    > }

    And it does get called rather often.


    \
     
     \ /
      Last update: 2009-05-02 00:41    [W:0.033 / U:46.556 seconds]
    ©2003-2017 Jasper Spaans. hosted at Digital OceanAdvertise on this site