Re: [Xen-devel] RE: tmem - really default to on?

[Tim Deegan <Tim.Deegan@xxxxxxxxxx>]

Hi,

At 17:18 +0000 on 08 Feb (1265649531), Dan Magenheimer wrote:
> The order=2 shadow page allocation should also probably be
> considered a "bug" for post-4.0 as, I think, even ballooning
> will eventually fragment memory and theoretically 75% of
> physical memory might be unused and domain creation (or PV
> migration) will fail.

I think the correct approach to all of this is to move system-wide to
allocating memory in 2MB contiguous aligned chunks.  There's no sense in
doing guest allocations any finer-grained than that and there are
noticeable performance wins from all the superpage support that's gone
in recently.  Then little things like needing 16k contiguous areas just
go away.

If that's not acceptable, I believe Christian Limpach looked at removing
the requirement for shadow memory to be contiguous as part of his
hosted-Xen project.  

Tim.

-- 
Tim Deegan <Tim.Deegan@xxxxxxxxxx>
Principal Software Engineer, XenServer Engineering
Citrix Systems UK Ltd.  (Company #02937203, SL9 0BG)

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