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Re: [Xen-devel] [PATCH] ioemu: directly project all memory on x86_64

To: Isaku Yamahata <yamahata@xxxxxxxxxxxxx>
Subject: Re: [Xen-devel] [PATCH] ioemu: directly project all memory on x86_64
From: Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>
Date: Thu, 24 Jan 2008 07:51:23 +0000
Cc: xen-ia64-devel@xxxxxxxxxxxxxxxxxxx, xen-devel@xxxxxxxxxxxxxxxxxxx, Samuel Thibault <samuel.thibault@xxxxxxxxxxxxx>
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On 24/1/08 02:40, "Isaku Yamahata" <yamahata@xxxxxxxxxxxxx> wrote:

>> Sure. I expect ia64 lags behind x86 in this respect.
> IA64 doesn't support HVM domain balloon yet.
> Presumably the first step for ia64 suport is to switch from direct
> mapping to mapcache (with 1:1 hash?) and see if perfromance degration
> is acceptable. But no one hasn't tried it yet.
> Anyway on ia64 memory might not be populated continuously,
> so some kind of tracking allocate/unallocate memory in qemu-dm
> is necessary in long term.

You won't have any degradation if you make mapcache a 1:1 map for ia64 (and
then also we can steal that code for x86_64!). mapcache already has the code
for tracking missing pages.

 -- Keir

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