lkml.org 
[lkml]   [2012]   [Mar]   [20]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: [PATCHSET] block: remove ioc_*_changed()
    On Mon, Mar 19, 2012 at 03:10:55PM -0700, Tejun Heo wrote:
    > Hello, guys.
    >
    > The changed notification used by cfq is rather odd. cfq caches the
    > associated cfqqs per cic and uses the changed notification to expire
    > those lookup caches.
    >
    > The explicit notification mechanism might make sense if determining
    > whether the current cache is up-to-date is difficult or expensive;
    > however, that isn't the case here. Determining whether ioprio or
    > cgroup has changed is straight-forward and inexpensive.
    >
    > This patchset updates cfq to so that it remembers the current ioprio
    > and blkcg in the cic and determines whether cfqq's need to be reset
    > without using the changed notification and drops the changed
    > notification code.

    Hi Tejun,

    So this patch still breaks cic->cfqq association in asynchronous
    manner, when new request comes in. So it will still not solve the
    problem I reported where after doing IO a task changes cgroup and
    tries to delete the old cgroup and hangs forever as cic->cfqq is still
    holding a reference to cgroup?

    Thanks
    Vivek


    \
     
     \ /
      Last update: 2012-03-20 16:53    [from the cache]
    ©2003-2014 Jasper Spaans. hosted at Digital Ocean