From: Andrew Morton <akpm@linux-foundation.org>
To: Vivek Goyal <vgoyal@redhat.com>
Cc: Tejun Heo <tj@kernel.org>,
avi@redhat.com, nate@cpanel.net, cl@linux-foundation.org,
oleg@redhat.com, axboe@kernel.dk, linux-kernel@vger.kernel.org
Subject: Re: [PATCHSET] block, mempool, percpu: implement percpu mempool and fix blkcg percpu alloc deadlock
Date: Tue, 27 Dec 2011 13:25:01 -0800 [thread overview]
Message-ID: <20111227132501.ad7f895f.akpm@linux-foundation.org> (raw)
In-Reply-To: <20111223145856.GB16818@redhat.com>
On Fri, 23 Dec 2011 09:58:56 -0500
Vivek Goyal <vgoyal@redhat.com> wrote:
> > Why do the allocation during I/O? Can't it be done in the hotplug handler?
> >
>
> Even if we can do it in hotplug handler it will be very wasteful of
> memory. So if there are 100 IO cgroups in the system, upon every block
> device hotplug, we will allocate per cpu memory for all the 100 cgroups,
> irrespective of the fact whether they are doing IO to the device or not.
>
> Now expand this to a system with 100 cgroups and 100 Luns. 10000
> allocations for no reason. (Even if we do it for cgroups needing stats,
> does not help much). Current scheme allocates memory for the group
> only if a sepcific cgroup is doing IO to a specific block device.
umm, we've already declared that it is OK to completely waste this
memory for the users (probably a majority) who will not be using
these stats.
Also, has this stuff been tested at that scale? I fear to think what
10000 allocations will do to fragmetnation of the vmalloc() arena.
next prev parent reply other threads:[~2011-12-27 21:25 UTC|newest]
Thread overview: 51+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-12-22 21:45 Tejun Heo
2011-12-22 21:45 ` [PATCH 1/7] mempool: fix and document synchronization and memory barrier usage Tejun Heo
2011-12-22 21:45 ` [PATCH 2/7] mempool: drop unnecessary and incorrect BUG_ON() from mempool_destroy() Tejun Heo
2011-12-22 21:45 ` [PATCH 3/7] mempool: fix first round failure behavior Tejun Heo
2011-12-22 21:45 ` [PATCH 4/7] mempool: factor out mempool_fill() Tejun Heo
2011-12-22 21:45 ` [PATCH 5/7] mempool: separate out __mempool_create() Tejun Heo
2011-12-22 21:45 ` [PATCH 6/7] mempool, percpu: implement percpu mempool Tejun Heo
2011-12-22 21:45 ` [PATCH 7/7] block: fix deadlock through percpu allocation in blk-cgroup Tejun Heo
2011-12-23 1:00 ` Vivek Goyal
2011-12-23 22:54 ` Tejun Heo
2011-12-22 21:59 ` [PATCHSET] block, mempool, percpu: implement percpu mempool and fix blkcg percpu alloc deadlock Andrew Morton
2011-12-22 22:09 ` Tejun Heo
2011-12-22 22:20 ` Andrew Morton
2011-12-22 22:41 ` Tejun Heo
2011-12-22 22:54 ` Andrew Morton
2011-12-22 23:00 ` Tejun Heo
2011-12-22 23:16 ` Andrew Morton
2011-12-22 23:24 ` Tejun Heo
2011-12-22 23:41 ` Andrew Morton
2011-12-22 23:54 ` Tejun Heo
2011-12-23 1:14 ` Andrew Morton
2011-12-23 15:17 ` Vivek Goyal
2011-12-27 18:34 ` Tejun Heo
2011-12-27 21:20 ` Andrew Morton
2011-12-27 21:44 ` Tejun Heo
2011-12-27 21:58 ` Andrew Morton
2011-12-27 22:22 ` Tejun Heo
2011-12-23 1:21 ` Vivek Goyal
2011-12-23 1:38 ` Andrew Morton
2011-12-23 2:54 ` Vivek Goyal
2011-12-23 3:11 ` Andrew Morton
2011-12-23 14:58 ` Vivek Goyal
2011-12-27 21:25 ` Andrew Morton [this message]
2011-12-27 22:07 ` Tejun Heo
2011-12-27 22:21 ` Andrew Morton
2011-12-27 22:30 ` Tejun Heo
2012-01-16 15:26 ` Vivek Goyal
2011-12-23 1:40 ` Vivek Goyal
2011-12-23 1:58 ` Andrew Morton
2011-12-23 2:56 ` Vivek Goyal
2011-12-26 6:05 ` KAMEZAWA Hiroyuki
2011-12-27 17:52 ` Tejun Heo
2011-12-28 0:14 ` KAMEZAWA Hiroyuki
2011-12-28 0:41 ` Tejun Heo
2012-01-05 1:28 ` Tejun Heo
2012-01-16 15:28 ` Vivek Goyal
2012-02-09 23:58 ` Tejun Heo
2012-02-10 16:26 ` Vivek Goyal
2012-02-13 22:31 ` Tejun Heo
2012-02-15 15:43 ` Vivek Goyal
2011-12-23 14:46 ` Vivek Goyal
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