From mboxrd@z Thu Jan 1 00:00:00 1970 From: Hollis Blanchard Subject: Re: [PATCH 0 of 6] PowerPC KVM patches for 2.6.29 Date: Wed, 03 Dec 2008 10:04:29 -0600 Message-ID: <1228320269.10084.7.camel@localhost.localdomain> References: <49366E68.4080904@redhat.com> Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Cc: kvm-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, kvm-ppc-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Christian Ehrhardt To: Avi Kivity Return-path: In-Reply-To: <49366E68.4080904-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org> Sender: kvm-ppc-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: kvm.vger.kernel.org On Wed, 2008-12-03 at 13:32 +0200, Avi Kivity wrote: > Hollis Blanchard wrote: > > Hi Avi, here's the latest batch of PowerPC kernel patches. > > > > The first set dramatically improve performance. Most importantly, we add > > support for large host pages with KVM (i.e. PAGE_SHIFT > 12). (Large *guest* > > pages have already been supported since day 1, since the guest kernel uses > > them for the linear map.) Followup patches further improve performance by > > changing how we manage the shadow TLB. > > > > The last two add some accounting code to easily discover performance > > bottlenecks. This is especially important since the 440 core lacks performance > > monitoring hardware. > > > > These patches, in conjunction with 64KB pages on guest and host, get us to 96% > > of native performance for compute-bound workloads, which I'm pretty happy > > with. See http://kvm.qumranet.com/kvmwiki/PowerPC_Exittimings for more > > details (those statistics were gathered using the accounting patches). > > > > These have been tested pretty thoroughly for several weeks. Please apply for > > 2.6.29. Thanks! > > > > Applied all, thanks. Thanks. > I'm not thrilled about the private exit timing statistics gathering, > hopefully it can be morphed into the more general framework. Is there anything in particular you have in mind? I think it could be generally useful, but since x86 has hardware support for performance monitoring, oprofile will already give you more accurate information. Of course, I don't think you could extract standard deviation from an oprofile report, and that has been very useful for us because it can tell us e.g. 99% of instruction emulation is handled in the minimum amount of time, but 1% takes hundreds of ms. I'll let Christian comment when he gets back from vacation on Monday. -- Hollis Blanchard IBM Linux Technology Center -- To unsubscribe from this list: send the line "unsubscribe kvm-ppc" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html