From mboxrd@z Thu Jan 1 00:00:00 1970 From: Peter Zijlstra Subject: Re: [PATCH v2 5/6] KVM-GST: adjust scheduler cpu power Date: Tue, 01 Feb 2011 19:59:31 +0100 Message-ID: <1296586771.26581.298.camel@laptop> References: <1296244340-15173-1-git-send-email-glommer@redhat.com> <1296244340-15173-6-git-send-email-glommer@redhat.com> <1296473120.15234.375.camel@laptop> <1296575996.5081.20.camel@mothafucka.localdomain> <1296577168.26581.240.camel@laptop> <1296577358.5081.23.camel@mothafucka.localdomain> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, aliguori@us.ibm.com, Rik van Riel , Jeremy Fitzhardinge , Avi Kivity To: Glauber Costa Return-path: In-Reply-To: <1296577358.5081.23.camel@mothafucka.localdomain> Sender: linux-kernel-owner@vger.kernel.org List-Id: kvm.vger.kernel.org On Tue, 2011-02-01 at 14:22 -0200, Glauber Costa wrote: > > > Which tick accounting? In your other e-mail , you pointed that this only > runs in touch_steal_time, which is fine, will change. That tick ;-), all the account_foo muck is per tick. > But all the rest > here, that is behind the hypervisor specific vs generic code has nothing > to do with ticks at all. But I don't get it, there is no generic code needed, all that's needed is u64 steal_time_clock(int cpu), and the first part of your kvm_account_steal_time() function is exactly that if you add the cpu argument. +static u64 steal_time_clock(int cpu) +{ + u64 steal_time; + struct kvm_steal_time *src; + int version; + + preempt_disable(); + src = &per_cpu_ptr(steal_time, cpu); + do { + version = src->version; + rmb(); + steal_time = src->steal; + rmb(); + } while ((src->version & 1) || (version != src->version)); + preempt_enable(); + + return steal_time +} And you're done.. no need to for any of that steal_time_{read,write} business.