lkml.org 
[lkml]   [2010]   [Dec]   [13]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    SubjectRe: [PATCH 16/35] writeback: increase min pause time on concurrent dirtiers
    From
    Date
    On Mon, 13 Dec 2010 22:47:02 +0800, Wu Fengguang said:
    > Target for >60ms pause time when there are 100+ heavy dirtiers per bdi.
    > (will average around 100ms given 200ms max pause time)

    > --- linux-next.orig/mm/page-writeback.c 2010-12-13 21:46:16.000000000 +0800
    > +++ linux-next/mm/page-writeback.c 2010-12-13 21:46:16.000000000 +0800
    > @@ -659,6 +659,27 @@ static unsigned long max_pause(unsigned
    > }
    >
    > /*
    > + * Scale up pause time for concurrent dirtiers in order to reduce CPU overheads.
    > + * But ensure reasonably large [min_pause, max_pause] range size, so that
    > + * nr_dirtied_pause (and hence future pause time) can stay reasonably stable.
    > + */
    > +static unsigned long min_pause(struct backing_dev_info *bdi,
    > + unsigned long max)
    > +{
    > + unsigned long hi = ilog2(bdi->write_bandwidth);
    > + unsigned long lo = ilog2(bdi->throttle_bandwidth);
    > + unsigned long t;
    > +
    > + if (lo >= hi)
    > + return 1;
    > +
    > + /* (N * 10ms) on 2^N concurrent tasks */
    > + t = (hi - lo) * (10 * HZ) / 1024;

    Either I need more caffeine, or the comment doesn't match the code
    if HZ != 1000?
    [unhandled content-type:application/pgp-signature]
    \
     
     \ /
      Last update: 2010-12-13 19:27    [W:3.220 / U:0.436 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site