Date: Wed, 19 Dec 2001 16:01:38 -0800 (PST) From: Matthew Dillon <dillon@apollo.backplane.com> To: Doug White <dwhite@resnet.uoregon.edu> Cc: <freebsd-current@FreeBSD.ORG> Subject: Re: Seeing a lot of 'microuptime() went backwards' messages during heavy disk I/O Message-ID: <200112200001.fBK01c721879@apollo.backplane.com> References: <Pine.BSF.4.33.0112191507080.36795-100000@resnet.uoregon.edu>
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:This has been asked on just about every FreeBSD list since the printf was
:added. Use the archives, man! :)
:
:This is when you have a device generating too much interrupt latency --
:enough to stall the RTC. Usually the offender is video cards, but in this
:case it could be your IDE controller.
This is on a SCSI machine, but I get your drift.
:The usual fix is to try changing timecounters; sysctl
:kern.timecounter.hardware tells you what you're currently using. If
:you're on CURRENT, it's probably using ACPI. If you want to override it
:back to TSC, put 'hint.acpi_timer.0.disabled="1"' in your
:/boot/device.hints. Also try compiling with or without apm since this
:influences the timecounter as well (although if you're on SMP you might be
:stuck with the i8254).
:
:phk can clarify. :)
:
:Doug White | FreeBSD: The Power to Serve
I would prefer that it figure out the correct time counter itself
rather then plague us with fraggin microuptime messages for the last N
years :-(
-Matt
Matthew Dillon
<dillon@backplane.com>
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