From: Tejun Heo <tj@kernel.org>
To: Vivek Goyal <vgoyal@redhat.com>
Cc: lizefan@huawei.com, axboe@kernel.dk,
containers@lists.linux-foundation.org, cgroups@vger.kernel.org,
linux-kernel@vger.kernel.org, ctalbott@google.com,
rni@google.com
Subject: Re: [PATCH 23/24] cfq-iosched: collect stats from dead cfqgs
Date: Wed, 2 Jan 2013 11:52:42 -0500 [thread overview]
Message-ID: <20130102165242.GD11220@mtj.dyndns.org> (raw)
In-Reply-To: <20130102164415.GB4306@redhat.com>
Hey, Vivek.
On Wed, Jan 02, 2013 at 11:44:15AM -0500, Vivek Goyal wrote:
> > > In fact if we have a realiable way of resetting status then online/offline
> > > infrastructure might not be required? I think per cpu stats will be a
> > > problem though and that's why we probably require logic to online/offline
> > > the group?
> >
> > Hmmm? What do you mean?
>
> I mean if we had a reliable way of resetting stats after transferring
> then we would not need to keep a track of whether group is online/offline.
> We could add everything and adding zero will not change anything. In fact
> it will also take care of residual IO (IO which happened after transfer
> of stats).
Ah... yeah, if we can do atomic transfer, we might be able to do away
with on/offlining. Couldn't think of a way to do that without
incurring overhead to hot paths.
> Or I missed the real reason of why do we have group online/offline
> infrastructure.
But given that on/offline state is something common to cgroup, I don't
think adding the states to blkcg is a bad idea. We need it for
reliable iterations anyways.
Thanks.
--
tejun
next prev parent reply other threads:[~2013-01-02 16:52 UTC|newest]
Thread overview: 56+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-12-28 20:35 [PATCHSET] block: implement blkcg hierarchy support in cfq, take#2 Tejun Heo
2012-12-28 20:35 ` [PATCH 01/24] cfq-iosched: Properly name all references to IO class Tejun Heo
2012-12-28 20:35 ` [PATCH 02/24] cfq-iosched: More renaming to better represent wl_class and wl_type Tejun Heo
2012-12-28 20:35 ` [PATCH 03/24] cfq-iosched: Rename "service_tree" to "st" at some places Tejun Heo
2012-12-28 20:35 ` [PATCH 04/24] cfq-iosched: Rename few functions related to selecting workload Tejun Heo
2012-12-28 20:35 ` [PATCH 05/24] cfq-iosched: Get rid of unnecessary local variable Tejun Heo
2012-12-28 20:35 ` [PATCH 06/24] cfq-iosched: Print sync-noidle information in blktrace messages Tejun Heo
2012-12-28 20:35 ` [PATCH 07/24] blkcg: fix minor bug in blkg_alloc() Tejun Heo
2012-12-28 20:35 ` [PATCH 08/24] blkcg: reorganize blkg_lookup_create() and friends Tejun Heo
2012-12-28 20:35 ` [PATCH 09/24] blkcg: cosmetic updates to blkg_create() Tejun Heo
2012-12-28 20:35 ` [PATCH 10/24] blkcg: make blkcg_gq's hierarchical Tejun Heo
2012-12-28 20:35 ` [PATCH 11/24] cfq-iosched: add leaf_weight Tejun Heo
2013-01-08 15:34 ` Vivek Goyal
2013-01-08 17:24 ` Tejun Heo
2012-12-28 20:35 ` [PATCH 12/24] cfq-iosched: implement cfq_group->nr_active and ->children_weight Tejun Heo
2013-01-08 15:51 ` Vivek Goyal
2012-12-28 20:35 ` [PATCH 13/24] cfq-iosched: implement hierarchy-ready cfq_group charge scaling Tejun Heo
2013-01-08 16:16 ` Vivek Goyal
2012-12-28 20:35 ` [PATCH 14/24] cfq-iosched: convert cfq_group_slice() to use cfqg->vfraction Tejun Heo
2013-01-08 16:42 ` Vivek Goyal
2012-12-28 20:35 ` [PATCH 15/24] cfq-iosched: enable full blkcg hierarchy support Tejun Heo
2013-01-07 16:34 ` [PATCH UPDATED " Tejun Heo
2013-01-08 14:42 ` Vivek Goyal
2013-01-08 17:19 ` Tejun Heo
2012-12-28 20:35 ` [PATCH 16/24] blkcg: add blkg_policy_data->plid Tejun Heo
2013-01-08 16:51 ` Vivek Goyal
2012-12-28 20:35 ` [PATCH 17/24] blkcg: implement blkcg_policy->on/offline_pd_fn() and blkcg_gq->online Tejun Heo
2013-01-02 19:38 ` Vivek Goyal
2013-01-02 20:37 ` Tejun Heo
2013-01-08 16:58 ` Vivek Goyal
2012-12-28 20:35 ` [PATCH 18/24] blkcg: s/blkg_rwstat_sum()/blkg_rwstat_total()/ Tejun Heo
2013-01-08 16:59 ` Vivek Goyal
2012-12-28 20:35 ` [PATCH 19/24] blkcg: implement blkg_[rw]stat_recursive_sum() and blkg_[rw]stat_merge() Tejun Heo
2013-01-08 18:03 ` Vivek Goyal
2012-12-28 20:35 ` [PATCH 20/24] block: RCU free request_queue Tejun Heo
2013-01-02 18:48 ` Vivek Goyal
2013-01-02 20:43 ` Tejun Heo
2013-01-08 18:05 ` Vivek Goyal
2012-12-28 20:35 ` [PATCH 21/24] blkcg: make blkcg_print_blkgs() grab q locks instead of blkcg lock Tejun Heo
2013-01-02 19:27 ` Vivek Goyal
2013-01-02 20:45 ` Tejun Heo
2013-01-08 18:08 ` Vivek Goyal
2012-12-28 20:35 ` [PATCH 22/24] cfq-iosched: separate out cfqg_stats_reset() from cfq_pd_reset_stats() Tejun Heo
2013-01-08 18:09 ` Vivek Goyal
2012-12-28 20:35 ` [PATCH 23/24] cfq-iosched: collect stats from dead cfqgs Tejun Heo
2013-01-02 16:24 ` Vivek Goyal
2013-01-02 16:30 ` Tejun Heo
2013-01-02 16:44 ` Vivek Goyal
2013-01-02 16:52 ` Tejun Heo [this message]
2013-01-08 18:12 ` Vivek Goyal
2012-12-28 20:35 ` [PATCH 24/24] cfq-iosched: add hierarchical cfq_group statistics Tejun Heo
2013-01-08 18:27 ` Vivek Goyal
2012-12-28 23:18 ` [PATCH 18.5/24] blkcg: export __blkg_prfill_rwstat() take#2 Tejun Heo
2013-01-02 18:20 ` [PATCHSET] block: implement blkcg hierarchy support in cfq, take#2 Vivek Goyal
2013-01-07 16:34 ` Tejun Heo
2013-01-08 18:28 ` Vivek Goyal
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