From: "Jan Beulich" <jbeulich@novell.com>
To: ruby young <yangyang@les.buaa.edu.cn>
Cc: xen-devel@lists.xensource.com
Subject: Re: Questions about memory zone
Date: Tue, 05 May 2009 09:25:32 +0100 [thread overview]
Message-ID: <4A00141C.76EA.0078.0@novell.com> (raw)
In-Reply-To: <4046dbfd0905050105l1054343ch6bac7b30eb0dde2c@mail.gmail.com>
>>> ruby young <yangyang@les.buaa.edu.cn> 05.05.09 10:05 >>>
>Hi, all~
>I'm interested in memory of xen. And I wondered what does the real mean of
>xen 'zone'. It seems different from linux 'zone'.
>In the source code of xen-3.3.0/xen/common/page_alloc.c, there is defined:
>#define pfn_dom_zone_type(_pfn) (fls(_pfn)-1)
>
>and NR_ZONES is defined:
>#define NR_ZONES (PADDR_BITS - PAGE_SHIFT)
>
>It seems Zone in xen set up as physic address and are separate by the last
>pfn bit set.
Correct.
>But Why does Xen Zone organize like this? And What does the Zone mean?
In order to be able to allocate memory based on address width restrictions,
without adding overhead on sorting memory as it gets (or after it got) freed.
Jan
prev parent reply other threads:[~2009-05-05 8:25 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-05-05 8:05 Questions about memory zone ruby young
2009-05-05 8:25 ` Jan Beulich [this message]
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