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Re: [Xen-devel] How much memory does a domain REALLY use...

To: "Graham, Simon" <Simon.Graham@xxxxxxxxxxx>, <xen-devel@xxxxxxxxxxxxxxxxxxx>
Subject: Re: [Xen-devel] How much memory does a domain REALLY use...
From: Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>
Date: Sat, 24 Feb 2007 19:38:05 +0000
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On 24/2/07 19:26, "Graham, Simon" <Simon.Graham@xxxxxxxxxxx> wrote:

>> Yes, there's an overhead of 7MB per 1GB on i386, and 12MB per 1GB on
>> x86/64.
> 
> What is the overhead for and where would I find it allocated?

24 bytes per 'struct page_info' and 4 bytes per machine_to_phys array entry.
The former is allocated at start-of-day near the top of arch/x86/mm.c. The
array of page_info structs is pointed at by 'frame_table'.

The overheads on x86/64 are 40 bytes per 'struct page_info' and 8 bytes per
machine_to_phys array entry.

 -- Keir



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