From mboxrd@z Thu Jan 1 00:00:00 1970 From: "David S. Ahern" Subject: Re: [RFC PATCH 0/3] generic hypercall support Date: Sat, 09 May 2009 22:27:10 -0600 Message-ID: <4A06579E.6060908@cisco.com> References: <4A010927.6020207@novell.com> <20090506072212.GV3036@sequoia.sous-sol.org> <4A018DF2.6010301@novell.com> <20090506160712.GW3036@sequoia.sous-sol.org> <4A031471.7000406@novell.com> <20090507233503.GA9103@amt.cnet> <20090507234311.GA9517@amt.cnet> <4A03E579.8030201@redhat.com> <20090508143507.GA8319@amt.cnet> <4A0445A0.4060104@novell.com> <20090508155109.GA9269@amt.cnet> <4A048E78.6020605@cisco.com> <4A048F93.1050601@novell.com> <4A04BEE5.2080600@cisco.com> <4A054296.4070604@redhat.com> <4A05689F.7020108@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: Avi Kivity , Gregory Haskins , Marcelo Tosatti , Chris Wright , kvm@vger.kernel.org, Anthony Liguori To: Gregory Haskins Return-path: Received: from sj-iport-6.cisco.com ([171.71.176.117]:12112 "EHLO sj-iport-6.cisco.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751079AbZEJE1P (ORCPT ); Sun, 10 May 2009 00:27:15 -0400 In-Reply-To: <4A05689F.7020108@gmail.com> Sender: kvm-owner@vger.kernel.org List-ID: Gregory Haskins wrote: > Avi Kivity wrote: >> David S. Ahern wrote: >>> I ran another test case with SMT disabled, and while I was at it >>> converted TSC delta to operations/sec. The results without SMT are >>> confusing -- to me anyways. I'm hoping someone can explain it. >>> Basically, using a count of 10,000,000 (per your web page) with SMT >>> disabled the guest detected a soft lockup on the CPU. So, I dropped the >>> count down to 1,000,000. So, for 1e6 iterations: >>> >>> without SMT, with EPT: >>> HC: 259,455 ops/sec >>> PIO: 226,937 ops/sec >>> MMIO: 113,180 ops/sec >>> >>> without SMT, without EPT: >>> HC: 274,825 ops/sec >>> PIO: 247,910 ops/sec >>> MMIO: 111,535 ops/sec >>> >>> Converting the prior TSC deltas: >>> >>> with SMT, with EPT: >>> HC: 994,655 ops/sec >>> PIO: 875,116 ops/sec >>> MMIO: 439,738 ops/sec >>> >>> with SMT, without EPT: >>> HC: 994,304 ops/sec >>> PIO: 903,057 ops/sec >>> MMIO: 423,244 ops/sec >>> >>> Running the tests repeatedly I did notice a fair variability (as much as >>> -10% down from these numbers). >>> >>> Also, just to make sure I converted the delta to ops/sec, the formula I >>> used was cpu_freq / dTSC * count = operations/sec >>> >>> >> The only think I can think of is cpu frequency scaling lying about the >> cpu frequency. Really the test needs to use time and not the time >> stamp counter. >> >> Are the results expressed in cycles/op more reasonable? > > FWIW: I always used kvm_stat instead of my tsc printk > kvm_stat shows same approximate numbers as with the TSC-->ops/sec conversions. Interestingly, MMIO writes are not showing up as mmio_exits in kvm_stat; they are showing up as insn_emulation. david >