linux-kernel - Re: [RFC v2] percpu: Add a separate function to merge free areas

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Message-ID: <20141204204534.GE4080@htj.dyndns.org>
Date:	Thu, 4 Dec 2014 15:45:34 -0500
From:	Tejun Heo <tj@...nel.org>
To:	Christoph Lameter <cl@...ux.com>
Cc:	Leonard Crestez <lcrestez@...acom.com>, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org, Sorin Dumitru <sdumitru@...acom.com>
Subject: Re: [RFC v2] percpu: Add a separate function to merge free areas

Hello, Christoph.

On Thu, Dec 04, 2014 at 02:28:10PM -0600, Christoph Lameter wrote:
> Well this is not a common use case and that is not what the per cpu
> allocator was designed for. There is bound to be signifcant fragmentation
> with the current design. The design was for rare allocations when
> structures are initialized.

My unverified gut feeling is that fragmentation prolly is a lot less
of a problem for percpu allocator given that most percpu allocations
are fairly small.  On the other hand, we do wanna pack them tight as
percpu memory is really expensive space-wise.  I could be wrong tho.

Thanks.

-- 
tejun
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