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From: Nick Piggin <nickpiggin@yahoo.com.au>
To: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: Eric Dumazet <dada1@cosmosbay.com>,
	Rik van Riel <riel@redhat.com>,
	linux-kernel <linux-kernel@vger.kernel.org>,
	linux-mm <linux-mm@kvack.org>,
	Ulrich Drepper <drepper@redhat.com>
Subject: Re: [PATCH] make MADV_FREE lazily free memory
Date: Thu, 12 Apr 2007 16:12:42 +1000	[thread overview]
Message-ID: <461DCDDA.2030502@yahoo.com.au> (raw)
In-Reply-To: <461DCCEB.70004@yahoo.com.au>

Nick Piggin wrote:
> Eric Dumazet wrote:
> 

>>> Two things can happen here.
>>>
>>> If this program used the pages before the kernel needed
>>> them, the program will be reusing its old pages.
>>
>>
>>
>> ah ok, this is because accessed/dirty bits are set by hardware and not 
>> a page fault.
> 
> 
> No it isn't.

That is to say, it isn't required for correctness. But if the
question was about avoiding a fault, then yes ;)

But as Linus recently said, even hardware handled faults still
take expensive microarchitectural traps.

> 
>> Is it true for all architectures ?
> 
> 
> No.
> 


-- 
SUSE Labs, Novell Inc.

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  reply	other threads:[~2007-04-12  6:12 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-04-11  4:30 Rik van Riel
2007-04-11 22:41 ` Eric Dumazet
2007-04-11 22:56   ` Rik van Riel
2007-04-12  5:44     ` Eric Dumazet
2007-04-12  6:08       ` Nick Piggin
2007-04-12  6:12         ` Nick Piggin [this message]
2007-04-12  7:22           ` Rik van Riel
2007-04-12 13:14             ` Nick Piggin
2007-04-12 20:58               ` Rik van Riel
2007-04-13  0:34                 ` Nick Piggin
2007-04-16 16:10             ` Anton Blanchard
2007-04-16 16:30               ` Jakub Jelinek
2007-04-16 18:39                 ` Anton Blanchard

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