I''m getting a lot of "Timer ISR: Time went backwards" printk''s, presumably thrown by xen''s arch time.c (line 395 in do_timer_interrupt). Is there some info I can provide to the team about this condition? I imagine there''s little I or the Xen team could do about this. But perhaps this alert is in there essentially as an assertion and developers are very interested in this situation. Otherwise, given that the box seems to run fine otherwise (except for presumably poor time resolution), I feel like shutting this up. Are there any approaches to managing xen''s printk or perhaps I should just maintain a local patch to comment out this notice? Platform is an old vmware 4. -- jared@wordzoo.com "Tiger gotta hunt. Bird gotta fly. Man gotta sit and wonder why, why, why. Tiger gotta sleep. Bird gotta land. Man gotta tell himself he understand." -- Kurt Vonnegut Jr. ------------------------------------------------------- The SF.Net email is sponsored by: Beat the post-holiday blues Get a FREE limited edition SourceForge.net t-shirt from ThinkGeek. It''s fun and FREE -- well, almost....http://www.thinkgeek.com/sfshirt _______________________________________________ Xen-devel mailing list Xen-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/xen-devel
> I''m getting a lot of "Timer ISR: Time went backwards" printk''s, > presumably thrown by xen''s arch time.c (line 395 in > do_timer_interrupt). > > Is there some info I can provide to the team about this condition?This is a quick ping about this issue, if indeed there is anything meaningful to say about this issue. I noticed in case more information was actually desired> I > imagine there''s little I or the Xen team could do about this. But > perhaps this alert is in there essentially as an assertion and > developers are very interested in this situation. > > Otherwise, given that the box seems to run fine otherwise (except for > presumably poor time resolution), I feel like shutting this up. Are > there any approaches to managing xen''s printk or perhaps I should just > maintain a local patch to comment out this notice? > > Platform is an old vmware 4. > > -- jared@wordzoo.com > > "Tiger gotta hunt. Bird gotta fly. > Man gotta sit and wonder why, why, why. > Tiger gotta sleep. Bird gotta land. > Man gotta tell himself he understand." -- Kurt Vonnegut Jr. >-- Jared Rhine <jared@wordzoo.com> ------------------------------------------------------- The SF.Net email is sponsored by: Beat the post-holiday blues Get a FREE limited edition SourceForge.net t-shirt from ThinkGeek. It''s fun and FREE -- well, almost....http://www.thinkgeek.com/sfshirt _______________________________________________ Xen-devel mailing list Xen-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/xen-devel
> > I''m getting a lot of "Timer ISR: Time went backwards" printk''s, > > presumably thrown by xen''s arch time.c (line 395 in > > do_timer_interrupt). > > > > Is there some info I can provide to the team about this condition?This is a quick ping about this issue, if indeed there is anything meaningful to say about this issue.> I noticed<ack, keyboard slip. sorry.> I meant to say I noticed that Scott Parish recently reported ntpd problems because of consistent backwards jumps. It occurred to me the problems might be related. I can guess, but could a developer say a few words about the issues involved with timer management and jumps under xen? I get the problems also under qemu and bochs (as well as the previously reported vmware), but I haven''t compared to a real machine yet. ------------------------------------------------------- The SF.Net email is sponsored by: Beat the post-holiday blues Get a FREE limited edition SourceForge.net t-shirt from ThinkGeek. It''s fun and FREE -- well, almost....http://www.thinkgeek.com/sfshirt _______________________________________________ Xen-devel mailing list Xen-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/xen-devel
Christian Limpach
2005-Jan-10 19:44 UTC
Re: [Xen-devel] Re: Ping: Timer ISR backwards notices
On Mon, Jan 10, 2005 at 09:42:25AM -0800, Jared Rhine wrote:> > > I''m getting a lot of "Timer ISR: Time went backwards" printk''s, > > I get the problems also under qemu and bochs (as well as the previously > reported vmware), but I haven''t compared to a real machine yet.I''ve seen these messages when running under vmware. The most likely cause for this is that the delay between when xen updates the domain''s time value and when the domain gets to read it can become arbitrarily large if the emulator gets descheduled by the host operating system or when the emulator has to schedule between multiple emulated/virtual machines. In that case the value read from the tsc can have advanced sufficiently so that the 32 bit we use to interpolate exact time has wrapped. christian ------------------------------------------------------- The SF.Net email is sponsored by: Beat the post-holiday blues Get a FREE limited edition SourceForge.net t-shirt from ThinkGeek. It''s fun and FREE -- well, almost....http://www.thinkgeek.com/sfshirt _______________________________________________ Xen-devel mailing list Xen-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/xen-devel