WARNING - OLD ARCHIVES

This is an archived copy of the Xen.org mailing list, which we have preserved to ensure that existing links to archives are not broken. The live archive, which contains the latest emails, can be found at http://lists.xen.org/
   
 
 
Xen 
 
Home Products Support Community News
 
   
 

xen-devel

[Xen-devel] Re: Why p2m allocation is from hap or shadow preallocated me

To: "Li, Xin B" <xin.b.li@xxxxxxxxx>
Subject: [Xen-devel] Re: Why p2m allocation is from hap or shadow preallocated memory?
From: Tim Deegan <Tim.Deegan@xxxxxxxxxxxxx>
Date: Tue, 7 Aug 2007 09:28:57 +0100
Cc: xen-devel@xxxxxxxxxxxxxxxxxxx
Delivery-date: Tue, 07 Aug 2007 01:27:58 -0700
Envelope-to: www-data@xxxxxxxxxxxxxxxxxx
In-reply-to: <B30DA1341B0CFA4893EF8A36B40B5C5D017D4B95@xxxxxxxxxxxxxxxxxxxxxxxxxxxx>
List-help: <mailto:xen-devel-request@lists.xensource.com?subject=help>
List-id: Xen developer discussion <xen-devel.lists.xensource.com>
List-post: <mailto:xen-devel@lists.xensource.com>
List-subscribe: <http://lists.xensource.com/cgi-bin/mailman/listinfo/xen-devel>, <mailto:xen-devel-request@lists.xensource.com?subject=subscribe>
List-unsubscribe: <http://lists.xensource.com/cgi-bin/mailman/listinfo/xen-devel>, <mailto:xen-devel-request@lists.xensource.com?subject=unsubscribe>
References: <B30DA1341B0CFA4893EF8A36B40B5C5D017D4B95@xxxxxxxxxxxxxxxxxxxxxxxxxxxx>
Sender: xen-devel-bounces@xxxxxxxxxxxxxxxxxxx
User-agent: Mutt/1.5.13 (2006-08-11)
Hi Xin,

At 15:54 +0800 on 07 Aug (1186502042), Li, Xin B wrote:
> And can we make p2m memory allocation from domain heap directly?

We shouldn't pull from the domheap directly because it's not accounted
for.  This was a problem with the old shadow code, which just kept
pulling un-owned pages from the domheap until it (or sometimes Xen) fell
over.  The shadow memory allocation is explicitly separate and can be
accounted to the guest that's using it and tracked by the tools.

There are still a number of places, particularly in the HVM platform
code, where unaccounted domheap memory is used for per-domain or
per-vcpu structures, but at least they're usually small (~1 page) and
static (no need to allocate more at run-time and have domains blow up
unpredictably, and reasonable confidence that domheap won't drain away
when we're not looking).

Tim.

-- 
Tim Deegan <Tim.Deegan@xxxxxxxxxxxxx>, XenSource UK Limited
Registered office c/o EC2Y 5EB, UK; company number 05334508

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel