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/
Home Products Support Community News


Re: [Xen-devel] Re: [GIT PULL] Xen for 2.6.30 #2

To: William Pitcock <nenolod@xxxxxxxxxxxxxxxx>
Subject: Re: [Xen-devel] Re: [GIT PULL] Xen for 2.6.30 #2
From: Ingo Molnar <mingo@xxxxxxx>
Date: Wed, 8 Apr 2009 16:38:37 +0200
Cc: Jeremy Fitzhardinge <jeremy@xxxxxxxx>, the arch/x86 maintainers <x86@xxxxxxxxxx>, Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>, Xen-devel <xen-devel@xxxxxxxxxxxxxxxxxxx>, Linux Kernel Mailing List <linux-kernel@xxxxxxxxxxxxxxx>
Delivery-date: Wed, 08 Apr 2009 07:40:04 -0700
Envelope-to: www-data@xxxxxxxxxxxxxxxxxxx
In-reply-to: <1238899134.5814.172.camel@petrie>
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: <49D1209A.9000800@xxxxxxxx> <49D25A42.7060300@xxxxxxxx> <20090331185541.GA17807@xxxxxxx> <49D2713D.6090401@xxxxxxxx> <20090403173623.GB6295@xxxxxxx> <1238899134.5814.172.camel@petrie>
Sender: xen-devel-bounces@xxxxxxxxxxxxxxxxxxx
User-agent: Mutt/1.5.18 (2008-05-17)
* William Pitcock <nenolod@xxxxxxxxxxxxxxxx> wrote:

> Hi,
> On Fri, 2009-04-03 at 19:36 +0200, Ingo Molnar wrote:
> > * Jeremy Fitzhardinge <jeremy@xxxxxxxx> wrote:
> > 
> > >> You know our stance which is very simple: dont put in Xen-only 
> > >> hooks that slow down native, and get rid of the existing Xen-only 
> > >> hooks.
> > >
> > > Yes, I understand that.  Unlike the pvops stuff, the dom0 changes 
> > > are largely all init-time and setup, and so have no performance 
> > > impact.
> > 
> > Yes, but once dom0 goes in your incentive to fix the native 
> > kernel performance drain we accumulated along the years of 
> > paravirt layers will be strongly weakened, right? :)
> There's plenty of incentive for everyone who has a stake in this 
> thing to ensure that paravirt performs equally to native. I do not 
> see how you could be legitimately concerned about that.

Well, instead of supposedly plenty of speculative incentives in the 
future i'd like to see the existing performance impact of paravirt 
features to be fixed here and now, before piling up new features. 
Which did not get fixed in the past two years, despite those plenty 
of incentives you claim.

This is a basic engineering principle: fix up existing performance 
impact before piling up more overhead.


Xen-devel mailing list

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