linux-kernel - Re: [PATCH percpu/for-3.17 2/2] blk-throttle: replace custom async percpu alloc mechanism with percpu

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Message-ID: <20140722005104.GI12921@htj.dyndns.org>
Date:	Mon, 21 Jul 2014 20:51:04 -0400
From:	Tejun Heo <tj@...nel.org>
To:	linux-kernel@...r.kernel.org
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Jens Axboe <axboe@...nel.dk>, Vivek Goyal <vgoyal@...hat.com>
Subject: Re: [PATCH percpu/for-3.17 2/2] blk-throttle: replace custom async
 percpu alloc mechanism with percpu_pool

On Fri, Jul 18, 2014 at 04:08:34PM -0400, Tejun Heo wrote:
> From 0a4bd997ba9725565883c688d7dcee8264abf71c Mon Sep 17 00:00:00 2001
> From: Tejun Heo <tj@...nel.org>
> Date: Fri, 18 Jul 2014 16:07:14 -0400
> 
> throtl_pd_init() is called under the queue lock but needs to allocate
> the percpu stats area.  This is currently handled by queueing it on a
> list and scheduling a work item to allocate and fill the percpu stats
> area.  Now that perpcu_pool is available, this custom mechanism can be
> replaced.
> 
> Add tg_stats_cpu_pool and implement tg_ensure_stats_cpu() which tries
> to make sure that tg->stats_cpu is populated to replace the custom
> async alloc mechanism.  As percpu_pool allocation can fail,
> tg_ensure_stats_cpu() is invoked whenever ->stats_cpu is about to be
> accessed.  This is similar to the way code was structured before as
> the custom async alloc could take arbitrary amount of time and each
> access should verify that ->stats_cpu is populated.
> 
> This simplifies the code.  There shouldn't be noticeable functional
> difference.
> 
> Signed-off-by: Tejun Heo <tj@...nel.org>
> Cc: Vivek Goyal <vgoyal@...hat.com>
> Cc: Jens Axboe <axboe@...nel.dk>

Jens, can I route this patch through percpu tree?

Thanks.

-- 
tejun
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