On Mon, Jun 29, 2009 at 01:27:47PM +0800, Gui Jianfeng wrote: > Hi Vivek, > > There's no need to travel the iocg->group_data for each iog > when exiting a elevator, that costs too much. An alternative > solution is reseting iocg_id as soon as an io group unlinking > from a iocg. Make a decision that whether it's need to carry > out deleting action by checking iocg_id. >
Thanks Gui. This makes sense to me. We can check iog->iocg_id to determine wheter group is still on iocg list or not instead of traversing the list. Nauman, do you see any issues with the patch? Thanks Vivek > Signed-off-by: Gui Jianfeng <[email protected]> > --- > block/elevator-fq.c | 29 ++++++++++------------------- > 1 files changed, 10 insertions(+), 19 deletions(-) > > diff --git a/block/elevator-fq.c b/block/elevator-fq.c > index d779282..b26fe0f 100644 > --- a/block/elevator-fq.c > +++ b/block/elevator-fq.c > @@ -2218,8 +2218,6 @@ void io_group_cleanup(struct io_group *iog) > BUG_ON(iog->sched_data.active_entity != NULL); > BUG_ON(entity != NULL && entity->tree != NULL); > > - iog->iocg_id = 0; > - > /* > * Wait for any rcu readers to exit before freeing up the group. > * Primarily useful when io_get_io_group() is called without queue > @@ -2376,6 +2374,7 @@ remove_entry: > group_node); > efqd = rcu_dereference(iog->key); > hlist_del_rcu(&iog->group_node); > + iog->iocg_id = 0; > spin_unlock_irqrestore(&iocg->lock, flags); > > spin_lock_irqsave(efqd->queue->queue_lock, flags); > @@ -2403,35 +2402,27 @@ done: > void io_group_check_and_destroy(struct elv_fq_data *efqd, struct io_group > *iog) > { > struct io_cgroup *iocg; > - unsigned short id = iog->iocg_id; > - struct hlist_node *n; > - struct io_group *__iog; > unsigned long flags; > struct cgroup_subsys_state *css; > > rcu_read_lock(); > > - BUG_ON(!id); > - css = css_lookup(&io_subsys, id); > + css = css_lookup(&io_subsys, iog->iocg_id); > > - /* css can't go away as associated io group is still around */ > - BUG_ON(!css); > + if (!css) > + goto out; > > iocg = container_of(css, struct io_cgroup, css); > > spin_lock_irqsave(&iocg->lock, flags); > - hlist_for_each_entry_rcu(__iog, n, &iocg->group_data, group_node) { > - /* > - * Remove iog only if it is still in iocg list. Cgroup > - * deletion could have deleted it already. > - */ > - if (__iog == iog) { > - hlist_del_rcu(&iog->group_node); > - __io_destroy_group(efqd, iog); > - break; > - } > + > + if (iog->iocg_id) { > + hlist_del_rcu(&iog->group_node); > + __io_destroy_group(efqd, iog); > } > + > spin_unlock_irqrestore(&iocg->lock, flags); > +out: > rcu_read_unlock(); > } > > -- 1.5.4.rc3 _______________________________________________ Containers mailing list [email protected] https://lists.linux-foundation.org/mailman/listinfo/containers _______________________________________________ Devel mailing list [email protected] https://openvz.org/mailman/listinfo/devel
