In message <[EMAIL PROTECTED]>, Bruce Evans writes:
>> 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.
The Gian removal doesn't come anywhere near this.
>The fact that the timecounter usually goes backwards by about 0.68 seconds
>is probably significant, but I can't quite explain it.
>> acpi_timer0: <32-bit timer at 3.579545MHz> port 0x808-0x80b on acpi0
2^32 / 3579545 = 1199.86 seconds.
2^24 / 3579545 = 4.68 seconds.
So even assuming that ACPI reported a wrong width, four seconds should
still be enough to prevent a wraparound even though we cycle through
the timecounter ring in one second.
>I just wrote the following fix for some of the overflow problems.
It is true that if a process is not running for arbitrary long time
the timecounter may be modified underneat it, and bruce's patch is
actually a pretty elegant solution for that case. By all means
I have had one other report of a similar problem, with the added
information that changing to the TSC or i8254 instead of PIXX
made it go away so I am not entirely convinced this is really what
we are looking for in this case.
Poul-Henning Kamp | UNIX since Zilog Zeus 3.20
[EMAIL PROTECTED] | TCP/IP since RFC 956
FreeBSD committer | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.
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