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

Re: [Xen-devel] Re: [PATCH 0/6] xen: don't call vmalloc_sync_all() when

To: Jeremy Fitzhardinge <jeremy@xxxxxxxx>
Subject: Re: [Xen-devel] Re: [PATCH 0/6] xen: don't call vmalloc_sync_all() when mapping foreign pages
From: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
Date: Thu, 22 Sep 2011 12:06:58 +0100
Cc: "xen-devel@xxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxx>, Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>, Stefano Stabellini <Stefano.Stabellini@xxxxxxxxxxxxx>, "linux-kernel@xxxxxxxxxxxxxxx" <linux-kernel@xxxxxxxxxxxxxxx>, David Vrabel <david.vrabel@xxxxxxxxxx>, Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Delivery-date: Thu, 22 Sep 2011 04:10:00 -0700
Envelope-to: www-data@xxxxxxxxxxxxxxxxxxx
In-reply-to: <4E7A3394.3090806@xxxxxxxx>
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/mailman/listinfo/xen-devel>, <mailto:xen-devel-request@lists.xensource.com?subject=subscribe>
List-unsubscribe: <http://lists.xensource.com/mailman/listinfo/xen-devel>, <mailto:xen-devel-request@lists.xensource.com?subject=unsubscribe>
References: <1316090411-22608-1-git-send-email-david.vrabel@xxxxxxxxxx> <4E727017.4030001@xxxxxxxx> <alpine.DEB.2.00.1109211124050.8700@kaball-desktop> <4E7A3394.3090806@xxxxxxxx>
Sender: xen-devel-bounces@xxxxxxxxxxxxxxxxxxx
User-agent: Alpine 2.00 (DEB 1167 2008-08-23)
On Wed, 21 Sep 2011, Jeremy Fitzhardinge wrote:
> On 09/21/2011 03:42 AM, Stefano Stabellini wrote:
> > On Thu, 15 Sep 2011, Jeremy Fitzhardinge wrote:
> >> This series is relying on regular ram mappings are already synced to all
> >> tasks, but I'm not sure that's necessarily guaranteed (for example, if
> >> you hotplug new memory into the domain, the new pages won't be mapped
> >> into every mm unless they're synced).
> > the series is using GFP_KERNEL, so this problem shouldn't occur, right?
> 
> What properties do you think GFP_KERNEL guarantees?

That the memory is below 4G and always mapped in the kernel 1:1 region.

Regarding memory hotplug it looks like that x86_32 is mapping new memory
ZONE_HIGHMEM, therefore avoiding any problems with GFP_KERNEL allocations.
On the other hand x86_64 is mapping the memory ZONE_NORMAL and calling
init_memory_mapping on the new range right away. AFAICT changes to
the 1:1 mapping in init_mm are automatically synced across all mm's
because the pgd is shared?

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

<Prev in Thread] Current Thread [Next in Thread>