From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Longpeng (Mike)" Subject: Re: [PATCH v2 0/4] KVM: optimize the kvm_vcpu_on_spin Date: Tue, 8 Aug 2017 16:14:27 +0800 Message-ID: <598972E3.1030807@huawei.com> References: <1502165135-4784-1-git-send-email-longpeng2@huawei.com> <20170808094153.1b5bf8f4@gondolin> Mime-Version: 1.0 Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: 7bit Cc: , , , , , , , , , , , , , To: Cornelia Huck Return-path: In-Reply-To: <20170808094153.1b5bf8f4@gondolin> Sender: linux-kernel-owner@vger.kernel.org List-Id: kvm.vger.kernel.org On 2017/8/8 15:41, Cornelia Huck wrote: > On Tue, 8 Aug 2017 12:05:31 +0800 > "Longpeng(Mike)" wrote: > >> This is a simple optimization for kvm_vcpu_on_spin, the >> main idea is described in patch-1's commit msg. > > I think this generally looks good now. > >> >> I did some tests base on the RFC version, the result shows >> that it can improves the performance slightly. > > Did you re-run tests on this version? Hi Cornelia, I didn't re-run tests on V2. But the major difference between RFC and V2 is that V2 only cache result for X86 (s390/arm needn't) and V2 saves a expensive operation ( 440-1400 cycles on my test machine ) for X86/VMX. So I think V2's performance is at least the same as RFC or even slightly better. :) > > I would also like to see some s390 numbers; unfortunately I only have a > z/VM environment and any performance numbers would be nearly useless > there. Maybe somebody within IBM with a better setup can run a quick > test? > > . > -- Regards, Longpeng(Mike)