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] Atomic operations

To: Timothy Hayes <hayesti@xxxxxx>
Subject: Re: [Xen-devel] Atomic operations
From: Keir Fraser <keir.fraser@xxxxxxxxxxxxx>
Date: Fri, 27 Mar 2009 17:56:24 +0000
Cc: Juergen Gross <juergen.gross@xxxxxxxxxxxxxxxxxxx>, "xen-devel@xxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxx>
Delivery-date: Fri, 27 Mar 2009 10:56:50 -0700
Envelope-to: www-data@xxxxxxxxxxxxxxxxxxx
In-reply-to: <f6ed2720903271022x7402508bsf2f7282f14fc08fd@xxxxxxxxxxxxxx>
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>
Sender: xen-devel-bounces@xxxxxxxxxxxxxxxxxxx
Thread-index: AcmvAKpTMk8HGTwdRoW7E0BFHewuugABK2AU
Thread-topic: [Xen-devel] Atomic operations
User-agent: Microsoft-Entourage/12.15.0.081119
The problem is that we dynamically remove LOCK_PREFIX when the guest has
only one vcpu. You need your own version of atomic.h in which you do not use
LOCK_PREFIX but use ?lock¹ directly instead. See
include/asm-i386/mach-xen/asm/sync_bitops.h for example, which is our
guaranteed inter-domain safe version of bitops.h.

 -- Keir

On 27/03/2009 17:22, "Timothy Hayes" <hayesti@xxxxxx> wrote:

> CONFIG_SMP=y
> CONFIG_X86_FIND_SMP_CONFIG=y
> CONFIG_X86_MPPARSE=y
> # CONFIG_X86_PC is not set
> CONFIG_X86_XEN=y
> 
> The problem occurs when I limit the VCPUs in each guest to 1, presumably they
> get scheduled into unique physical CPUs in parallel. Is there anything else I
> should be aware of? I'm quite optimistic that the XenSocket logic is sound,
> the only thing I can attribute this to is a lack of atomicity.



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

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