Subject: Re: kern/18910: time(1) reports garbage user and system times
To: None <email@example.com>
From: David Laight <firstname.lastname@example.org>
Date: 11/04/2002 08:35:56
> on a dual AMD Athlon 1800 running a multiprocessor kernel, the output
> from time(1) frequently has garbage in the user and/or system time
> fields. Here are two specimens:
> 9051.58 real 4255.13 user -140461532.55 sys
> 3970.16 real -1306333211.13 user -1446799052.29 sys
These are 'usually' caused by microtime going backwards.
The MP kernel (and current 1.6) use a completely different microtime
implementation to the systems Chuck and I did a lot of investigation
on, I think MP systems use a different timer interrupt as well.....
Anything that sets the clock (eg NTP) is very likely to cause
microtime to decrease, unfortunately the scheduler doesn't really
There are also a few other lurking problems that cause the output from
time to be incorrect. I think I've already raised PRs for them.
David Laight: email@example.com