Date: Sat, 16 Feb 2002 16:28:26 -0800 (PST) From: Matthew Dillon <dillon@apollo.backplane.com> To: freebsd-current@freebsd.org Subject: 'microuptime() went backwards ...' using ACPI timer. Shouldn't that be impossible? Message-ID: <200202170028.g1H0SQZ41827@apollo.backplane.com>
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Testing with a 'make -j 10 buildworld' on a -current box I am getting
regular:
microuptime() went backwards (146.826785 -> 146.156715)
microuptime() went backwards (146.826782 -> 146.228636)
...
microuptime() went backwards (8945.938288 -> 8945.251603)
microuptime() went backwards (8945.938306 -> 8945.347173)
microuptime() went backwards (9142.847550 -> 9142.847546)
This occurs both with and without the gettimeofday Giant-removal patch, so
I am fairly sure it has nothing to do with any of my current work. This is
running -current on a DELL2550 (2xCPUs), compiled with the SMP option.
Timecounter "i8254" frequency 1193182 Hz
...
Timecounter "ACPI" frequency 3579545 Hz
acpi_timer0: <32-bit timer at 3.579545MHz> port 0x808-0x80b on acpi0
acpi_cpu0: <CPU> on acpi0
acpi_cpu1: <CPU> on acpi0
acpi_pcib0: <Host-PCI bridge> on acpi0
...
Question: How can this be occuring at all? Isn't the ACPI counter a
32 bit counter that does not have the rollover problems that the 8254 timer
has?
-Matt
Matthew Dillon
<dillon@backplane.com>
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