lkml.org 
[lkml]   [2010]   [Oct]   [8]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    From
    Date
    SubjectRE: [PATCH] bdi: use deferable timer for sync_supers task

    > On Fri, 2010-10-08 at 12:04 +0200, ext Wu, Xia wrote:
    > > On Fri, Oct 08, 2010 at 04:35:14PM +0800, Yong Wang wrote:
    > > > > sync_supers task currently wakes up periodically for superblock
    > > > > writeback. This hurts power on battery driven devices. This patch
    > > > > turns this housekeeping timer into a deferable timer so that it
    > > > > does not fire when system is really idle.
    > >
    > > > How long can the timer be defereed? We can't simply stop writing
    > > > out data for a long time. I think the current timer value should be
    > > > the upper bound, but allowing to fire earlier to run during the
    > > > same wakeup cycle as others is fine.
    > >
    > > If the system is in sleep state, this timer can be deferred to the next wake-up interrupt.
    > > If the system is busy, this timer will fire at the scheduled time.

    > However, when the next wake-up interrupt happens is not defined. It can
    > happen 1ms after, or 1 minute after, or 1 hour after. What Christoph
    > says is that there should be some guarantee that sb writeout starts,
    > say, within 5 to 10 seconds interval. Deferrable timers do not guarantee
    > this. But take a look at the range hrtimers - they do exactly this.

    If the system is in sleep state, is there any data which should be written? Must
    sb writeout start even there isn't any data?

    \
     
     \ /
      Last update: 2010-10-08 12:29    [W:0.025 / U:30.204 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site