From: Tejun Heo <tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
To: Jeff Moyer <jmoyer-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
Cc: axboe-tSWWG44O7X1aa/9Udqfwiw@public.gmane.org,
vgoyal-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org,
ctalbott-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org,
rni-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org,
linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
containers-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org,
fengguang.wu-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org,
hughd-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org,
akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org
Subject: Re: [PATCH 11/11] blkcg: implement per-blkg request allocation
Date: Fri, 27 Apr 2012 08:02:17 -0700 [thread overview]
Message-ID: <20120427150217.GK27486@google.com> (raw)
In-Reply-To: <x49wr51usxi.fsf-RRHT56Q3PSP4kTEheFKJxxDDeQx5vsVwAInAS/Ez/D0@public.gmane.org>
Hello,
On Fri, Apr 27, 2012 at 10:54:01AM -0400, Jeff Moyer wrote:
> > This patch implements per-blkg request_list. Each blkg has its own
> > request_list and any IO allocates its request from the matching blkg
> > making blkcgs completely isolated in terms of request allocation.
>
> So, nr_requests is now actually nr_requests * # of blk cgroups. Is that
> right? Are you at all concerned about the amount of memory that can be
> tied up as the number of cgroups increases?
Yeah, I thought about it and I don't think there's a single good
solution here. The other extreme would be splitting nr_requests by
the number of cgroups but that seems even worse - each cgroup should
be able to hit maximum throughput. Given that a lot of workloads tend
to regulate themselves before hitting nr_requests, I think it's best
to leave it as-is and treat each cgroup as having separate channel for
now. It's a configurable parameter after all.
Thanks.
--
tejun
WARNING: multiple messages have this Message-ID (diff)
From: Tejun Heo <tj@kernel.org>
To: Jeff Moyer <jmoyer@redhat.com>
Cc: axboe@kernel.dk, vgoyal@redhat.com, ctalbott@google.com,
rni@google.com, linux-kernel@vger.kernel.org,
cgroups@vger.kernel.org, containers@lists.linux-foundation.org,
fengguang.wu@intel.com, hughd@google.com,
akpm@linux-foundation.org
Subject: Re: [PATCH 11/11] blkcg: implement per-blkg request allocation
Date: Fri, 27 Apr 2012 08:02:17 -0700 [thread overview]
Message-ID: <20120427150217.GK27486@google.com> (raw)
In-Reply-To: <x49wr51usxi.fsf@segfault.boston.devel.redhat.com>
Hello,
On Fri, Apr 27, 2012 at 10:54:01AM -0400, Jeff Moyer wrote:
> > This patch implements per-blkg request_list. Each blkg has its own
> > request_list and any IO allocates its request from the matching blkg
> > making blkcgs completely isolated in terms of request allocation.
>
> So, nr_requests is now actually nr_requests * # of blk cgroups. Is that
> right? Are you at all concerned about the amount of memory that can be
> tied up as the number of cgroups increases?
Yeah, I thought about it and I don't think there's a single good
solution here. The other extreme would be splitting nr_requests by
the number of cgroups but that seems even worse - each cgroup should
be able to hit maximum throughput. Given that a lot of workloads tend
to regulate themselves before hitting nr_requests, I think it's best
to leave it as-is and treat each cgroup as having separate channel for
now. It's a configurable parameter after all.
Thanks.
--
tejun
next prev parent reply other threads:[~2012-04-27 15:02 UTC|newest]
Thread overview: 77+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-04-26 21:59 [PATCHSET] block: implement per-blkg request allocation Tejun Heo
2012-04-26 21:59 ` Tejun Heo
2012-04-26 21:59 ` [PATCH 09/11] block: add q->nr_rqs[] and move q->rq.elvpriv to q->nr_rqs_elvpriv Tejun Heo
[not found] ` <1335477561-11131-1-git-send-email-tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
2012-04-26 21:59 ` [PATCH 01/11] blkcg: fix blkg_alloc() failure path Tejun Heo
2012-04-26 21:59 ` Tejun Heo
[not found] ` <1335477561-11131-2-git-send-email-tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
2012-04-27 14:26 ` Vivek Goyal
2012-04-27 14:26 ` Vivek Goyal
[not found] ` <20120427142652.GH10579-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2012-04-27 14:27 ` Tejun Heo
2012-04-27 14:27 ` Tejun Heo
2012-04-27 14:27 ` Tejun Heo
2012-04-27 14:26 ` Vivek Goyal
2012-04-26 21:59 ` [PATCH 02/11] blkcg: __blkg_lookup_create() doesn't have to fail on radix tree preload failure Tejun Heo
2012-04-26 21:59 ` Tejun Heo
[not found] ` <1335477561-11131-3-git-send-email-tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
2012-04-27 14:42 ` Vivek Goyal
2012-04-27 14:42 ` Vivek Goyal
[not found] ` <20120427144258.GI10579-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2012-04-27 14:47 ` Tejun Heo
2012-04-27 14:47 ` Tejun Heo
2012-04-27 14:47 ` Tejun Heo
2012-04-27 21:18 ` [PATCH UPDATED 02/11] blkcg: __blkg_lookup_create() doesn't need radix preload Tejun Heo
2012-04-27 21:18 ` Tejun Heo
2012-04-27 21:18 ` Tejun Heo
2012-04-26 21:59 ` [PATCH 03/11] blkcg: make root blkcg allocation use %GFP_KERNEL Tejun Heo
2012-04-26 21:59 ` Tejun Heo
[not found] ` <1335477561-11131-4-git-send-email-tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
2012-04-27 21:19 ` [PATCH UPDATED " Tejun Heo
2012-04-27 21:19 ` Tejun Heo
2012-04-26 21:59 ` [PATCH 04/11] mempool: add @gfp_mask to mempool_create_node() Tejun Heo
2012-04-26 21:59 ` Tejun Heo
2012-04-26 21:59 ` [PATCH 05/11] block: drop custom queue draining used by scsi_transport_{iscsi|fc} Tejun Heo
2012-04-26 21:59 ` Tejun Heo
[not found] ` <1335477561-11131-6-git-send-email-tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
2012-05-02 4:55 ` Mike Christie
2012-05-02 4:55 ` Mike Christie
2012-05-02 4:55 ` Mike Christie
2012-04-26 21:59 ` [PATCH 06/11] block: refactor get_request[_wait]() Tejun Heo
2012-04-26 21:59 ` Tejun Heo
2012-04-26 21:59 ` [PATCH 07/11] block: allocate io_context upfront Tejun Heo
2012-04-26 21:59 ` Tejun Heo
2012-04-26 21:59 ` [PATCH 08/11] blkcg: inline bio_blkcg() and friends Tejun Heo
2012-04-26 21:59 ` Tejun Heo
2012-04-26 21:59 ` [PATCH 09/11] block: add q->nr_rqs[] and move q->rq.elvpriv to q->nr_rqs_elvpriv Tejun Heo
2012-04-26 21:59 ` [PATCH 10/11] block: prepare for multiple request_lists Tejun Heo
2012-04-26 21:59 ` Tejun Heo
2012-04-26 21:59 ` [PATCH 11/11] blkcg: implement per-blkg request allocation Tejun Heo
2012-04-26 21:59 ` Tejun Heo
[not found] ` <1335477561-11131-12-git-send-email-tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
2012-04-27 14:54 ` Jeff Moyer
2012-04-27 14:54 ` Jeff Moyer
[not found] ` <x49wr51usxi.fsf-RRHT56Q3PSP4kTEheFKJxxDDeQx5vsVwAInAS/Ez/D0@public.gmane.org>
2012-04-27 15:02 ` Tejun Heo
2012-04-27 15:02 ` Tejun Heo [this message]
2012-04-27 15:02 ` Tejun Heo
[not found] ` <20120427150217.GK27486-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>
2012-04-27 15:40 ` Vivek Goyal
2012-04-27 15:40 ` Vivek Goyal
[not found] ` <20120427154033.GJ10579-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2012-04-27 15:45 ` Tejun Heo
2012-04-27 15:45 ` Tejun Heo
2012-04-27 15:45 ` Tejun Heo
[not found] ` <20120427154502.GM27486-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>
2012-04-27 15:48 ` Vivek Goyal
2012-04-27 15:48 ` Vivek Goyal
2012-04-27 15:48 ` Vivek Goyal
[not found] ` <20120427154841.GA16237-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2012-04-27 15:51 ` Tejun Heo
2012-04-27 15:51 ` Tejun Heo
[not found] ` <20120427155140.GN27486-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>
2012-04-27 15:56 ` Vivek Goyal
2012-04-27 15:56 ` Vivek Goyal
[not found] ` <20120427155612.GK10579-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2012-04-27 16:19 ` Vivek Goyal
2012-04-27 16:19 ` Vivek Goyal
2012-04-27 16:20 ` Tejun Heo
2012-04-27 16:20 ` Tejun Heo
[not found] ` <20120427162012.GP27486-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>
2012-04-27 17:21 ` Vivek Goyal
2012-04-27 17:21 ` Vivek Goyal
[not found] ` <20120427172110.GM10579-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2012-04-27 17:25 ` Tejun Heo
2012-04-27 17:25 ` Tejun Heo
2012-04-27 17:25 ` Tejun Heo
2012-04-27 17:21 ` Vivek Goyal
2012-04-27 19:46 ` Vivek Goyal
2012-04-27 19:46 ` Vivek Goyal
[not found] ` <20120427194654.GN10579-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2012-04-27 20:15 ` Tejun Heo
2012-04-27 20:15 ` Tejun Heo
[not found] ` <20120427201516.GJ26595-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>
2012-04-27 20:21 ` Vivek Goyal
2012-04-27 20:21 ` Vivek Goyal
2012-04-27 20:21 ` Vivek Goyal
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