From: Vivek Goyal <vgoyal@redhat.com>
To: Jeff Moyer <jmoyer@redhat.com>
Cc: Tejun Heo <tj@kernel.org>,
axboe@kernel.dk, ctalbott@google.com, rni@google.com,
linux-kernel@vger.kernel.org,
Kent Overstreet <koverstreet@google.com>
Subject: Re: [PATCH 34/36] block: implement bio_associate_current()
Date: Wed, 22 Feb 2012 14:37:59 -0500 [thread overview]
Message-ID: <20120222193759.GB7635@redhat.com> (raw)
In-Reply-To: <x494nuizmqw.fsf@segfault.boston.devel.redhat.com>
On Wed, Feb 22, 2012 at 02:33:43PM -0500, Jeff Moyer wrote:
> Tejun Heo <tj@kernel.org> writes:
>
> > Hey, Jeff.
>
> Hi, Tejun!
>
> > On Wed, Feb 22, 2012 at 08:45:02AM -0500, Jeff Moyer wrote:
> >> Tejun Heo <tj@kernel.org> writes:
> >>
> >> > -v2: #ifdef CONFIG_BLK_CGROUP added around bio->bi_ioc dereference in
> >> > rq_ioc() to fix build breakage.
> >>
> >> This is useful for cfq without blk cgroups as well, right? Why have you
> >> limited the scope like this?
> >
> > Because blk-throttle is the only current user. We can move the
> > BLK_CGROUP to cover just bi_css later on as we add more users.
>
> I guess you're going to make me read the whole patch set. ;-) What I'm
> getting at is CFQ uses the io_context to make its scheduling decisions.
> If we can propagate the issuer's I/O context from bio creation all the
> way down to the I/O scheduler, then we can do a better job of accounting
> I/O (and hence scheduling, preemption, etc). As Vivek mentioned
> previously, we have seen performance issues with the dm-crypt target and
> CFQ, precisely because all of the I/O is submitted in the context of a
> worker thread, and the the process that initiated the I/O is unknown at
> that point.
>
> Hopefully I've either cleared up my question, or proven to you that I do
> need to go read the rest of the patch set to understand why my question
> doesn't make sense. Let me know which is the case. ;-)
Currently he has put the bio_associate() hook only in blk_throtl_bio()
which is under CONFIG_BLK_CGROUP. It is agreed upon that this mechanism
looks generally useful and probably submit_bio() is a better place to
put the hook. Tejun mentioned that once things work well, later we can
think of making the functionality more generic. In that case we shall
have to remove the cgroup specific #ifdefs.
Thansk
Vivek
next prev parent reply other threads:[~2012-02-22 19:38 UTC|newest]
Thread overview: 58+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-02-22 1:46 [PATCHSET] blkcg: accumulated blkcg updates Tejun Heo
2012-02-22 1:46 ` [PATCH 01/36] block: blk-throttle should be drained regardless of q->elevator Tejun Heo
2012-02-22 1:46 ` [PATCH 02/36] blkcg: make CONFIG_BLK_CGROUP bool Tejun Heo
2012-02-22 1:46 ` [PATCH 03/36] cfq: don't register propio policy if !CONFIG_CFQ_GROUP_IOSCHED Tejun Heo
2012-02-22 1:46 ` [PATCH 04/36] elevator: clear auxiliary data earlier during elevator switch Tejun Heo
2012-02-22 1:46 ` [PATCH 05/36] elevator: make elevator_init_fn() return 0/-errno Tejun Heo
2012-02-22 1:46 ` [PATCH 06/36] block: implement blk_queue_bypass_start/end() Tejun Heo
2012-02-22 1:46 ` [PATCH 07/36] block: extend queue bypassing to cover blkcg policies Tejun Heo
2012-02-22 1:46 ` [PATCH 08/36] blkcg: shoot down blkio_groups on elevator switch Tejun Heo
2012-02-22 1:46 ` [PATCH 09/36] blkcg: move rcu_read_lock() outside of blkio_group get functions Tejun Heo
2012-02-22 1:46 ` [PATCH 10/36] blkcg: update blkg get functions take blkio_cgroup as parameter Tejun Heo
2012-02-22 1:46 ` [PATCH 11/36] blkcg: use q and plid instead of opaque void * for blkio_group association Tejun Heo
2012-02-22 1:46 ` [PATCH 12/36] blkcg: add blkio_policy[] array and allow one policy per policy ID Tejun Heo
2012-02-22 1:46 ` [PATCH 13/36] blkcg: use the usual get blkg path for root blkio_group Tejun Heo
2012-02-22 1:46 ` [PATCH 14/36] blkcg: factor out blkio_group creation Tejun Heo
2012-02-22 1:46 ` [PATCH 15/36] blkcg: don't allow or retain configuration of missing devices Tejun Heo
2012-02-22 1:46 ` [PATCH 16/36] blkcg: kill blkio_policy_node Tejun Heo
2012-02-22 1:46 ` [PATCH 17/36] blkcg: kill the mind-bending blkg->dev Tejun Heo
2012-02-22 1:46 ` [PATCH 18/36] blkcg: let blkio_group point to blkio_cgroup directly Tejun Heo
2012-02-22 1:46 ` [PATCH 19/36] blkcg: add blkcg_{init|drain|exit}_queue() Tejun Heo
2012-02-22 1:46 ` [PATCH 20/36] blkcg: clear all request_queues on blkcg policy [un]registrations Tejun Heo
2012-02-22 1:46 ` [PATCH 21/36] blkcg: let blkcg core handle policy private data allocation Tejun Heo
2012-02-22 1:46 ` [PATCH 22/36] blkcg: move refcnt to blkcg core Tejun Heo
2012-02-22 1:46 ` [PATCH 23/36] blkcg: make blkg->pd an array and move configuration and stats into it Tejun Heo
2012-02-22 1:46 ` [PATCH 24/36] blkcg: don't use blkg->plid in stat related functions Tejun Heo
2012-02-22 1:46 ` [PATCH 25/36] blkcg: move per-queue blkg list heads and counters to queue and blkg Tejun Heo
2012-02-22 1:46 ` [PATCH 26/36] blkcg: let blkcg core manage per-queue blkg list and counter Tejun Heo
2012-02-22 1:46 ` [PATCH 27/36] blkcg: unify blkg's for blkcg policies Tejun Heo
2012-03-05 21:01 ` [PATCH UPDATED " Tejun Heo
2012-02-22 1:46 ` [PATCH 28/36] blkcg: use double locking instead of RCU for blkg synchronization Tejun Heo
2012-02-22 1:46 ` [PATCH 29/36] blkcg: drop unnecessary RCU locking Tejun Heo
2012-02-23 18:51 ` [PATCH UPDATED " Tejun Heo
2012-02-22 1:46 ` [PATCH 30/36] block: restructure get_request() Tejun Heo
2012-02-22 1:46 ` [PATCH 31/36] block: interface update for ioc/icq creation functions Tejun Heo
2012-02-22 1:46 ` [PATCH 32/36] block: ioc_task_link() can't fail Tejun Heo
2012-02-22 1:47 ` [PATCH 33/36] block: add io_context->active_ref Tejun Heo
2012-02-22 18:47 ` Vivek Goyal
2012-02-22 19:13 ` Tejun Heo
2012-02-23 18:20 ` Vivek Goyal
2012-02-22 1:47 ` [PATCH 34/36] block: implement bio_associate_current() Tejun Heo
2012-02-22 13:45 ` Jeff Moyer
2012-02-22 19:07 ` Tejun Heo
2012-02-22 19:33 ` Jeff Moyer
2012-02-22 19:37 ` Vivek Goyal [this message]
2012-02-22 19:41 ` Jeff Moyer
2012-02-22 1:47 ` [PATCH 35/36] block: make block cgroup policies follow bio task association Tejun Heo
2012-02-22 1:47 ` [PATCH 36/36] block: make blk-throttle preserve the issuing task on delayed bios Tejun Heo
2012-02-22 19:34 ` [PATCHSET] blkcg: accumulated blkcg updates Vivek Goyal
2012-02-22 22:04 ` Tejun Heo
2012-03-05 20:59 ` [PATCH 17.5] blkcg: skip blkg printing if q isn't associated with disk Tejun Heo
2012-03-05 21:07 ` [PATCHSET] blkcg: accumulated blkcg updates Tejun Heo
2012-03-05 21:08 ` Tejun Heo
2012-03-06 15:07 ` Vivek Goyal
2012-03-06 16:24 ` Vivek Goyal
2012-03-06 18:39 ` Vivek Goyal
2012-03-06 18:39 ` Vivek Goyal
2012-03-06 19:02 ` Vivek Goyal
2012-03-08 0:06 ` Tejun Heo
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