linux-kernel - Re: Pagecache zeroing: zero_user_segment, zero_user_segments and zero

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Message-ID: <464A9BD1.1030300@yahoo.com.au>
Date:	Wed, 16 May 2007 15:51:13 +1000
From:	Nick Piggin <nickpiggin@...oo.com.au>
To:	Andrew Morton <akpm@...ux-foundation.org>
CC:	Christoph Lameter <clameter@....com>, linux-kernel@...r.kernel.org,
	Satyam Sharma <satyam.sharma@...il.com>,
	Nate Diller <nate.diller@...il.com>
Subject: Re: Pagecache zeroing: zero_user_segment, zero_user_segments and
 zero_user

Andrew Morton wrote:
> On Wed, 16 May 2007 14:52:05 +1000 Nick Piggin <nickpiggin@...oo.com.au> wrote:

>>>On the other hand non highmem platforms are burdened with always repeating
>>>the same KM_USER0 in every function call. Isnt it enough to know that 
>>>standard functions use KM_USER0 for their operations?
>>
>>Couldn't that be filtered out inline?
> 
> 
> It is - there is no runtime overhead for non-highmem machines.
> 
> The problem nowadays is all the developers who don't need, have, compile
> for or test on highmem machines.

Well sure, if that's all Christoph is worried about, then it isn't
really valid because in generic code we have to follow the architecture
abstraction API -- there is no "non highmem platform" in generic code :)

-- 
SUSE Labs, Novell Inc.
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