From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jeremy Fitzhardinge Subject: Re: [ RfC / patch ] kvmclock fixes Date: Mon, 21 Apr 2008 23:38:19 +1000 Message-ID: <480C98CB.4000209@goop.org> References: <20080407213457.GA4473@dmt> <20080419152947.GA30610@dmt> <5d6222a80804190922me58c7d1ycb5c38bcf13b94a8@mail.gmail.com> <20080419164947.GA31253@dmt> <480C3F05.1060009@redhat.com> <480C516D.7080809@redhat.com> <480C64FD.4040004@goop.org> <480C9011.7080507@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: kvm-devel@lists.sourceforge.net, Marcelo Tosatti To: Gerd Hoffmann Return-path: In-Reply-To: <480C9011.7080507@redhat.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: kvm-devel-bounces@lists.sourceforge.net Errors-To: kvm-devel-bounces@lists.sourceforge.net List-Id: kvm.vger.kernel.org Gerd Hoffmann wrote: > +cycle_t pvclock_clocksource_read(struct kvm_vcpu_time_info *src) > +{ > + struct pvclock_shadow_time *shadow; > + cycle_t ret; > + unsigned version; > + > + shadow = &get_cpu_var(shadow_time); > + do { > + version = pvclock_get_time_values(shadow, src); > + barrier(); > + ret = shadow->system_timestamp + pvclock_get_nsec_offset(shadow); > + barrier(); > Is barrier() strong enough? Does kvm guarantee that the per-cpu time parameters are only ever updated by that cpu? I'm pretty sure Xen does, so that's OK. J ------------------------------------------------------------------------- This SF.net email is sponsored by the 2008 JavaOne(SM) Conference Don't miss this year's exciting event. There's still time to save $100. Use priority code J8TL2D2. http://ad.doubleclick.net/clk;198757673;13503038;p?http://java.sun.com/javaone