Date: Sat, 5 Jul 2008 15:56:49 -0700 From: "David Allen" <the.real.david.allen@gmail.com> To: freebsd-questions@freebsd.org Subject: Re: calcru: runtime went backwards errors Message-ID: <2daa8b4e0807051556t2ac2f42bgd5d2f23bf2c880d7@mail.gmail.com> In-Reply-To: <54db43990806300738n33d10fe7te27b9c9f3c295a4@mail.gmail.com> References: <2daa8b4e0806300627s39d49347r9e0e5675e4c25088@mail.gmail.com> <54db43990806300738n33d10fe7te27b9c9f3c295a4@mail.gmail.com>
next in thread | previous in thread | raw e-mail | index | archive | help
On Mon, Jun 30, 2008 at 7:38 AM, Bob Johnson <fbsdlists@gmail.com> wrote: > On 6/30/08, David Allen <the.real.david.allen@gmail.com> wrote: >> I've been seeing errors like the following appearing: >> >> Jun 30 03:13:57 ford kernel: calcru: runtime went backwards from 261 >> usec to 258 usec for pid 516 (devd) > [...] >> Jun 30 03:13:57 ford kernel: calcru: runtime went backwards from 486 >> usec to 481 usec for pid 0 (swapper) >> >> and narrowed down the cause to openntpd. >> >> Do these errors fall into the Mostly Harmless category? > > It's probably just an annoyance, unless it is happening so often it > causes other problems. I'll not worry then, but what's perplexing is that if "time going backwards" leads to confusion, why is that ntpd, as a matter of course, doesn't result in these error messages, but openntpd does? And then, why isn't anyone using openntpd getting the errors? > The FreeBSD FAQ used to have a nice explanation of this, but it has > been replaced by a discussion that simply assumes the problem is > caused by the Intel SpeedStep implementation on your motherboard: > http://www.freebsd.org/doc/en_US.ISO8859-1/books/faq/troubleshoot.html#Q5.24. My web searches turned a lot of noise about the above issue. Thanks for clarifying what I was reading. As for the FAQ, didn't there was one. I guess I've not needed it until now. ;-) > But in general, this error can be caused by several things, including > a device that is slow to respond to interrupts. One thing that often > helps on SMP systems is to make sure your timecounter isn't using TSC: > > $ sysctl kern.timecounter > kern.timecounter.tick: 1 > kern.timecounter.choice: TSC(-100) HPET(900) ACPI-fast(1000) i8254(0) > dummy(-1000000) > kern.timecounter.hardware: ACPI-fast > [...] Good to know, but this is an older single processor system (ACPI-safe). Seems I'll have to decide whether I drop openntpd and shuffle things around to other systems, or learn to live with the errors. Thanks to everyone that replied.
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?2daa8b4e0807051556t2ac2f42bgd5d2f23bf2c880d7>