lkml.org 
[lkml]   [2010]   [Nov]   [30]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    From
    SubjectRe: Free memory never fully used, swapping
    Date
    Hi

    > > > > > out:
    > > > > > - if (!all_zones_ok) {
    > > > > > + if (!(all_zones_ok || (order && any_zone_ok))) {
    > > > >
    > > > > This doesn't work ;)
    > > > > kswapd have to clear ZONE_CONGESTED flag before enter sleeping.
    > > > > otherwise nobody can clear it.
    > > > >
    > > >
    > > > Does it not do it earlier in balance_pgdat() here
    > > >
    > > > /*
    > > > * If a zone reaches its high watermark,
    > > > * consider it to be no longer congested. It's
    > > > * possible there are dirty pages backed by
    > > > * congested BDIs but as pressure is
    > > > * relieved, spectulatively avoid congestion waits
    > > > */
    > > > zone_clear_flag(zone, ZONE_CONGESTED);
    > > > if (i <= pgdat->high_zoneidx)
    > > > any_zone_ok = 1;
    > >
    > > zone_clear_flag(zone, ZONE_CONGESTED) only clear one zone status. other
    > > zone remain old status.
    > >
    >
    > Ah now I get you. kswapd does not necessarily balance all zones so it needs
    > to unconditionally clear them all before it goes to sleep in case. At
    > some time in the future, the tagging of ZONE_CONGESTED needs more
    > thinking about.
    >

    This is a option.


    > > > > Say, we have to fill below condition.
    > > > > - All zone are successing zone_watermark_ok(order-0)
    > > >
    > > > We should loop around at least once with order == 0 where all_zones_ok
    > > > is checked.
    > >
    > > But no gurantee. IOW kswapd early stopping increase GFP_ATOMIC allocation
    > > failure risk, I think.
    > >
    >
    > Force all zones to be balanced for order-0?

    Yes.

    I think following change does.

    if (i <= pgdat->high_zoneidx)
    - any_zone_ok = 1;
    + order = sc.order = 0;


    This is more conservative.





    \
     
     \ /
      Last update: 2010-11-30 12:21    [W:0.024 / U:0.196 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site