linux-kernel - Re: 2.6.33 pagemap endless read loop

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Message-ID: <20100112153208.GF3925@hack>
Date:	Tue, 12 Jan 2010 23:32:08 +0800
From:	Américo Wang <xiyou.wangcong@...il.com>
To:	Andi Kleen <andi@...stfloor.org>
Cc:	Américo Wang <xiyou.wangcong@...il.com>,
	linux-kernel@...r.kernel.org
Subject: Re: 2.6.33 pagemap endless read loop

On Sun, Jan 10, 2010 at 01:37:02PM +0100, Andi Kleen wrote:
>> Are you sure
>
>I don't know if it's really endless, but it's doing a good emulation
>of it if it's not.
>
>> 
>> On my 32bit machine, it runs for a long time, but finally exits.
>
>That was on 64bit.
>
>proc01 had accumulated several minutes of CPU time when I stopped it.
>
>> From the document of pagemap, it is the mapping of all the virtual pages
>> of a process, on x86-32, it should be 4G/4K = 1024*1024 pages, also
>
>Only the mapped ones surely?
>
>Right now it looks like it dumps all the holes and that obviously
>will never finish on 64bit which has 47bits of address space.
>

Hmm, could you please try:

     time cat /proc/self/pagemap >/dev/null

? Is it much faster than:

     time cat /proc/self/pagemap

?

Thanks!
-- 
Live like a child, think like the god.
 
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