linux-kernel - Re: [PATCHSET] block, mempool, percpu: implement percpu mempool and fix blkcg percpu alloc deadlock

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Message-ID: <20111222220911.GK17084@google.com>
Date:	Thu, 22 Dec 2011 14:09:11 -0800
From:	Tejun Heo <tj@...nel.org>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	avi@...hat.com, nate@...nel.net, cl@...ux-foundation.org,
	oleg@...hat.com, axboe@...nel.dk, vgoyal@...hat.com,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCHSET] block, mempool, percpu: implement percpu mempool
 and fix blkcg percpu alloc deadlock

Hello,

On Thu, Dec 22, 2011 at 01:59:25PM -0800, Andrew Morton wrote:
> How about we just delete those statistics and then this patchset?
> 
> Or how about we change those statistics to not do percpu allocations,
> then delete this patchset?

I'm not against above both but apparently those percpu stats reduced
CPU overhead significantly.

> Or how about we fix the percpu memory allocation code so that it
> propagates the gfp flags, then delete this patchset?

Oh, no, this is gonna make things *way* more complex.  I tried.  If
we're gonna have many more NOIO percpu users, which I don't think we
would or should, that might make sense but, for fringe cases,
extending mempool to cover percpu is a much better sized solution.

Thanks.

-- 
tejun
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