When vm.overcommit_memory = 2 and there appears to be about 2M of memory
readily available and about 12M of memory allocated to pagecache (this
is info gathered from /proc/meminfo) , a call to malloc(5000000) returns
NULL. I would have expected that somehow, the call to malloc(5000000)
would request the memory in pagecache to be released for use by the app.
-----Original Message-----
From: Robert Hancock [mailto:[email protected]]
Sent: Tuesday, April 10, 2007 10:15 AM
To: Mouawad, Tony
Cc: [email protected]
Subject: Re: Help Understanding Linux memory management
Mouawad, Tony wrote:
> Hello,
>
> I've been a MS Windows based programmer for a very long time and was
> recently tossed in an environment where I am developing embedded apps
on
> the m68k / Linux platform. That makes me a Linux newbie. I started
> asking a few questions on various IRC channels and was directed to
this
> group. So, I will start asking:
>
> These are questions derived from observations on the MCF 5475 CPU
> running Linux 2.6.10 built for the m68k platform. Disk swapping is
> disabled.
>
> 1) When physical memory runs low, the memory manager will try to use
> memory currently allocated to the pagecache. Is this true?
Yes.
> 2) When vm.overcommit_memory = 2 (overcommit disabled), and memory
runs
> low, it appears that the memory manager does not try to use memory
> currently allocated to pagecache. Is this true?
Shouldn't be, what makes you think this is happening?
> 3) Is it possible to disable the pagecache?
Not as far as I know, it's unlikely this would be of any benefit.
--
Robert Hancock Saskatoon, SK, Canada
To email, remove "nospam" from [email protected]
Home Page: http://www.roberthancock.com/
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