lkml.org 
[lkml]   [2011]   [Jun]   [7]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: [PATCH 02/15] writeback: update dirtied_when for synced inode to prevent livelock
    On Wed, 08 Jun 2011 05:32:38 +0800
    Wu Fengguang <fengguang.wu@intel.com> wrote:

    > Explicitly update .dirtied_when on synced inodes, so that they are no
    > longer considered for writeback in the next round.

    It sounds like this somewhat answers my questions for [1/15].

    But I'm not seeing a description of exactly what caused the livelock.

    > We'll do more aggressive "keep writeback as long as we wrote something"
    > logic in wb_writeback(). The "use LONG_MAX .nr_to_write" trick in commit
    > b9543dac5bbc ("writeback: avoid livelocking WB_SYNC_ALL writeback") will
    > no longer be enough to stop sync livelock.
    >
    > It can prevent both of the following livelock schemes:
    >
    > - while true; do echo data >> f; done
    > - while true; do touch f; done

    You're kidding. This livelocks sync(1)? When did we break this?

    Why is this? Because the inode keeps on getting rotated to head-of-list?


    \
     
     \ /
      Last update: 2011-06-08 01:07    [W:0.020 / U:0.352 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site