linux-kernel - Re: [PATCH 03/15] percpu: remove the usage of separate populated bitmap in percpu-vm

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Message-ID: <alpine.DEB.2.11.1408231054580.29970@gentwo.org>
Date:	Sat, 23 Aug 2014 10:57:47 -0500 (CDT)
From:	Christoph Lameter <cl@...ux.com>
To:	Tejun Heo <tj@...nel.org>
cc:	akpm@...ux-foundation.org, laijs@...fujitsu.com,
	linux-kernel@...r.kernel.org, vgoyal@...hat.com
Subject: Re: [PATCH 03/15] percpu: remove the usage of separate populated
 bitmap in percpu-vm

On Fri, 22 Aug 2014, Tejun Heo wrote:

> percpu-vm uses pcpu_get_pages_and_bitmap() to acquire temp pages array
> and populated bitmap and uses the two during [de]population.  The temp
> bitmap is used only to build the new bitmap that is copied to
> chunk->populated after the operation succeeds; however, the new bitmap
> can be trivially set after success without using the temp bitmap.

Ok so that follows from the all or nothing allocation approach. Either all
the pages have been allocated then you can set the bits or not then you
clear them.

Acked-by: Christoph Lameter <cl@...ux.com>
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