From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jeremy Fitzhardinge Subject: Re: A clocksource question Date: Thu, 11 Mar 2010 16:49:30 -0800 Message-ID: <4B998F9A.3040706@goop.org> References: <4B962748.90609@invisiblethingslab.com> <4B96DB69.10101@goop.org 4B981997.4030605@invisiblethingslab.com> <56cc3abf-21f6-4178-b00e-0331538080d9@default> <4FA716B1526C7C4DB0375C6DADBC4EA3554D53F1B0@LONPMAILBOX01.citrite.net> <4B983EC9.2030105@invisiblethingslab.com> <4B98421F.7040102@goop.org> <4B984533.9030402@invisiblethingslab.com> <4B9877CA.4060204@goop.org> <4B998A70.3050500@invisiblethingslab.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <4B998A70.3050500@invisiblethingslab.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: Joanna Rutkowska Cc: Ian Pratt , "xen-devel@lists.xensource.com" , Dan Magenheimer List-Id: xen-devel@lists.xenproject.org On 03/11/2010 04:27 PM, Joanna Rutkowska wrote: > I think that the important clue is this message appearing in my dmesg > (in Dom0 and also in DomUs): > > hrtimer: interrupt too slow, forcing clock min delta to 540150561 ns > > This is almost 0.5s (!) and I think this might explain my kbd hiccup. I > wrote that I feel it every 10s or so, but when I was playing on my > system without jiffies setting today, I saw this hiccup occurring much > more often; in fact it was more of a "slow keyboard/system" feeling than > a hiccup". > Yes, its definitely a good clue. It could point to a Xen scheduler issue (I assume you don't have any other busy domains when this is going on), but that wouldn't explain why it works OK with jiffies. Perhaps there's a problem with programming the timer so that sometimes it gets missed and the system doesn't get a kick until some subsequent event (whereas with clocksource=jiffies there'll always be a timer in the next 100ms). J