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Re: [Xen-devel] Page cache shared across domain

To: Mark Williamson <mark.williamson@xxxxxxxxxxxx>
Subject: Re: [Xen-devel] Page cache shared across domain
From: Amit Patel <amitpate@xxxxxxxxx>
Date: Mon, 30 Jan 2006 08:36:18 -0800
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Thanks for quick response. As you mentioned some of the efforts are
underway. If I want to contirbute how do I get more information? Is
there specific people working on this or if I can help with testing
out this stuff.


On 1/24/06, Mark Williamson <mark.williamson@xxxxxxxxxxxx> wrote:
> There are a number of routes for this.  The most obvious is to implement
> content-based page sharing mechanisms for the hypervisor itself - I believe
> people are working on this already.  This is what VMware ESX does when
> running multiple guests, and can unify storage for pages when they have the
> same content.
> Another approach is to use a shared interdomain ramdisk and do Execute In
> Place (XIP) on the contents.  It's not a full shared page cache, but it gives
> you sharing for program text, etc.  I'm implementing infrastructure to
> support the dcssblk driver used on IBM zSeries mainframes, which will give us
> this functionality.
> The most invasive approach is to implement a Xen-aware filesystem - I'm
> working on this too.  XenFS and the DCSS work require similar infrastructure
> (including an enhanced version of grant tables, and more functionality in the
> Xenstore to support more complicated "device" sharing relationships) so the
> two efforts are symbiotic.  The port of the dcssblk driver is less
> sophisticated and will likely be available substantially sooner.
> HTH,
> Mark
> On Tuesday 24 January 2006 07:38, Amit Patel wrote:
> > Hi,
> >
> > I just got started using Xen. Is there any mechanism in Xen which
> > allows pages shared across multiple domains? I was reading documents
> > regarding grant tables but one limitation it states, is that a page
> > using this mechanism  can only be shared between two domains and only
> > one of them has control over pages at anytime. I was looking for
> > something where any domain has access to this shared memory and can be
> > accessed by any domain in read only mode. Any help if its possible to
> > do with Xen and where can I look for information is appreciated.
> >
> >
> > TIA
> >
> > Siva
> >
> > _______________________________________________
> > Xen-devel mailing list
> > Xen-devel@xxxxxxxxxxxxxxxxxxx
> > http://lists.xensource.com/xen-devel
> --
> Dave: Just a question. What use is a unicyle with no seat?  And no pedals!
> Mark: To answer a question with a question: What use is a skateboard?
> Dave: Skateboards have wheels.
> Mark: My wheel has a wheel!

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