From mboxrd@z Thu Jan 1 00:00:00 1970 From: Benjamin LaHaise Subject: Re: [patch 28/34] Xen-pv_ops: Xen SMP guest support Date: Wed, 14 Mar 2007 09:28:20 -0400 Message-ID: <20070314132820.GL6209@kvack.org> References: <20070313233017.933601256@goop.org> <20070313233034.586018620@goop.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <20070313233034.586018620@goop.org> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: Jeremy Fitzhardinge Cc: Zachary Amsden , xen-devel@lists.xensource.com, virtualization@lists.osdl.org, Rusty Russell , linux-kernel@vger.kernel.org, Andi Kleen , Chris Wright , Andi Kleen , Ingo Molnar , Andrew Morton List-Id: virtualization@lists.linuxfoundation.org On Tue, Mar 13, 2007 at 04:30:45PM -0700, Jeremy Fitzhardinge wrote: > [ brcl, mingo: Would you mind having a close look at the code in > xen_exit_mm and drop_mm_ref? - Thanks ] I see what you're doing here, and this comment seems to allude to the reasons behind it without spelling it out. > +/* > + * We aggressively remove defunct pgd from cr3. We execute unmap_vmas() > + * *much* faster this way. > + */ Are you switching mms in order to avoid all of the overhead associated with flushing an active mm during task exit? If so, it makes much more sense to do this in the generic helper, as it should be a win on x86 and x86-64 where switching to init_mm is relatively low cost given the support for global pages. I'll run some tests on a couple of systems this evening and post the results. -ben -- "Time is of no importance, Mr. President, only life is important." Don't Email: .