Messages in this thread | | | Date | Thu, 2 Apr 2009 09:52:02 -0400 | From | Vivek Goyal <> | Subject | Re: [PATCH 02/10] Common flat fair queuing code in elevaotor layer |
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On Wed, Apr 01, 2009 at 09:06:40PM -0700, Divyesh Shah wrote: > On Wed, Mar 11, 2009 at 6:56 PM, Vivek Goyal <vgoyal@redhat.com> wrote: > > +/* > > + * elv_exit_fq_data is called before we call elevator_exit_fn. Before > > + * we ask elevator to cleanup its queues, we do the cleanup here so > > + * that all the group and idle tree references to ioq are dropped. Later > > + * during elevator cleanup, ioc reference will be dropped which will lead > > + * to removal of ioscheduler queue as well as associated ioq object. > > + */ > > +void elv_exit_fq_data(struct elevator_queue *e) > > +{ > > + struct elv_fq_data *efqd = &e->efqd; > > + struct request_queue *q = efqd->queue; > > + > > + if (!elv_iosched_fair_queuing_enabled(e)) > > + return; > > + > > + elv_shutdown_timer_wq(e); > > + > > + spin_lock_irq(q->queue_lock); > > + /* This should drop all the idle tree references of ioq */ > > + elv_free_idle_ioq_list(e); > > + spin_unlock_irq(q->queue_lock); > > + > > + elv_shutdown_timer_wq(e); > > + > > + BUG_ON(timer_pending(&efqd->idle_slice_timer)); > > + io_free_root_group(e); > > +} > > > > Hi Vivek, > When cleaning up the elv_fq_data and ioqs for the iogs > associated with a device on elv_exit(), I don't see any iogs except > the root group being freed. In io_disconnect_groups() you remove the > ioqs from each of the iog and move them to the root iog and then > delete the root iog. Am I missing something here or are there leftover > iogs at elv_exit?
Hi Divyesh,
io_groups are linked in two lists. One list is maintained by io_cgroup to keep track of how many io_groups are there associated with this cgroup and other list is maintained in elv_fq_data to keep track of how many io_groups are actually doing IO to this device.
Upon elevator exit, we remove the io_groups (io_disconnect_groups())from the list maintained by elv_fq_data but we don't free them up. Freeing up is finally done when cgroup is being deleted (iocg_destroy()).
Thanks Vivek
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