From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrew Cooper Subject: Re: [PATCH] x86/watchdog: Use real timestamps for watchdog timeout Date: Fri, 24 May 2013 15:29:34 +0100 Message-ID: <519F794E.5050802@citrix.com> References: <20130524093712.GA54769@ocelot.phlegethon.org> <519F3AED.2090209@citrix.com> <519F2E5D02000078000D8AA7@nat28.tlf.novell.com> <519F3994.7040008@citrix.com> <20130524101312.GB54769@ocelot.phlegethon.org> <519F6CD602000078000D8BE5@nat28.tlf.novell.com> <20130524124158.GC54769@ocelot.phlegethon.org> <519F61AF.2070203@citrix.com> <20130524135549.GA57961@ocelot.phlegethon.org> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20130524135549.GA57961@ocelot.phlegethon.org> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: Tim Deegan Cc: "Keir (Xen.org)" , Jan Beulich , "xen-devel@lists.xen.org" List-Id: xen-devel@lists.xenproject.org On 24/05/13 14:55, Tim Deegan wrote: > At 13:48 +0100 on 24 May (1369403327), Andrew Cooper wrote: >> On 24/05/13 13:41, Tim Deegan wrote: >>> Of those two, I prefer (1), just because it doesn't add any cost to the >>> normal users of NOW(). >> I was not planning to make any requirement to change users of NOW(). > Well, you were planning to make NOW() slightly more expensive by needing > to look up which of the banekd alternatives is valid. In any case, I > think some sort of approximate version based on tsc will do. > > Tim. I was planning to memcpy the shadow set over the main set as part of calibration, leaving no alteration whatsoever to NOW(). An approximation from the TSC alone would be better so long as it is a reasonable approximation. I am concerned about how accuate a dumb approximation would be for non-stable TSCs etc. ~Andrew