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] Linux spin lock enhancement on xen

To: Keir Fraser <keir.fraser@xxxxxxxxxxxxx>
Subject: Re: [Xen-devel] Linux spin lock enhancement on xen
From: Mukesh Rathor <mukesh.rathor@xxxxxxxxxx>
Date: Wed, 18 Aug 2010 19:52:31 -0700
Cc: Jeremy Fitzhardinge <jeremy@xxxxxxxx>, "Xen-devel@xxxxxxxxxxxxxxxxxxx" <Xen-devel@xxxxxxxxxxxxxxxxxxx>
Delivery-date: Wed, 18 Aug 2010 19:54:38 -0700
Envelope-to: www-data@xxxxxxxxxxxxxxxxxxx
In-reply-to: <C891D252.1E4BD%keir.fraser@xxxxxxxxxxxxx>
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>
Organization: Oracle Corporation
References: <4C6C0C3D.2070508@xxxxxxxx> <C891D252.1E4BD%keir.fraser@xxxxxxxxxxxxx>
Sender: xen-devel-bounces@xxxxxxxxxxxxxxxxxxx
On Wed, 18 Aug 2010 18:09:22 +0100
Keir Fraser <keir.fraser@xxxxxxxxxxxxx> wrote:

> On 18/08/2010 17:37, "Jeremy Fitzhardinge" <jeremy@xxxxxxxx> wrote:
> 
> > I don't see why the guest should micromanage Xen's scheduler
> > decisions. If a VCPU is waiting for another VCPU and can put itself
> > to sleep in the meantime, then its up to Xen to take advantage of
> > that newly freed PCPU to schedule something.  It may decide to run
> > something in your domain that's runnable, or it may decide to run
> > something else.  There's no reason why the spinlock holder is the
> > best VCPU to run overall, or even the best VCPU in your domain.
> > 
> > My view is you should just put any VCPU which has nothing to do to
> > sleep, and let Xen sort out the scheduling of the remainder.
> 
> Yeah, I'm no fan of yield or yield-to type operations. I'd reserve
> the right to implement both of them as no-op.
> 
>  -- Keir
> 

I think making them advisory makes sense. Ultimately xen decides. 

thanks,
Mukesh


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