Time jumping on both 4.x and 5.x ...

Kris Kennaway kris at obsecurity.org
Fri Nov 28 18:51:39 PST 2003


On Fri, Nov 28, 2003 at 09:32:30PM -0400, Marc G. Fournier wrote:
> 
> In trying to isolate an issue where the PostgreSQL 'explain analyze' is
> showing "odd results" (namely, negative time estimates on queries), Tom
> Lane wrote a quick C program to test gettimeofday() (program attached) ...
> the results on a 4.9-PRERELEASE kernel of Sep 20 14:16:48 ADT 2003 shows:
> 
> neptune# time ./timetest
> out of order tv_sec: 1070068479 99040, prev 1070069174 725235
> out of order tv_usec: 1070068479 99040, prev 1070069174 725235
> out of order tv_sec: 1070069175 19687, prev 1070068479 99040
> out of order tv_usec: 1070069175 19687, prev 1070068479 99040
> out of order tv_sec: 1070068499 99377, prev 1070069194 625573
> out of order tv_usec: 1070068499 99377, prev 1070069194 625573
> out of order tv_sec: 1070069194 808542, prev 1070068499 99377
> ^C1.171u 23.461s 0:24.68 99.7%  5+169k 1+0io 0pf+0w
> 
> One person on the list has tried the same script on a 5.2 kernel, and
> reports seeing similar results, but after a longer period of time (~30min)
> ...

What hardware, kernel configuration, etc?  Do you have a misconfigured
ntpd/timed that is manually flapping the time around?

I've run that test for a few minutes on 4.9 without problems.

Kris
-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Type: application/pgp-signature
Size: 187 bytes
Desc: not available
Url : http://lists.freebsd.org/pipermail/freebsd-current/attachments/20031128/74629ac6/attachment.bin


More information about the freebsd-current mailing list