Date: Thu, 20 Jan 2000 22:39:50 +0000 From: Ben Smithurst <ben@scientia.demon.co.uk> To: Scott Blachowicz <Scott.Blachowicz@seaslug.org> Cc: freebsd-questions@freebsd.org Subject: Re: Odd gettimeofday() return values Message-ID: <20000120223950.A24986@strontium.scientia.demon.co.uk> In-Reply-To: <uaem1v3l5.fsf@seaslug.org> References: <uaem1v3l5.fsf@seaslug.org>
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Scott Blachowicz wrote:
> $1 = {tv_sec = 948333207, tv_usec = -694210779}
>
> I'm not sure when this really started happening - I think it's been going
> on for a while now (the earliest I see in my log files is mid-November, so
> I guess it's not a Y2K bug :-)). At any rate, shouldn't that tv_usec
> field be in the range of 0..999999? If not, how should I hack the source
> here to interpret the above return value? Borrow enough seconds off of
> tv_sec until tv_usec is positive? Clamp tv_usec to zero? Or do something
> equivalent to this:
>
> if (tv_usec < 0 || tv_usec > 1000000) {
> now.tv_sec = time(NULL);
this is just as unreliable, since time() just calls gettimeofday().
> now.tv_usec = 0;
> }
>
> ??? Any ideas/suggestions?
>
> Also...I don't know if it's related or not, but I've gotten some of those
>
> Jan 19 06:28:55 sabmail /kernel: calcru: negative time of -695391396 usec for pid 85131 (awk)
I'd guess they're related, the numbers are quite close (relatively at
least). All I can suggest really is upgrade to the latest -STABLE,
unless someone has a better idea. I recall talk of this calcru problem
being fixed (I used to see it a bit, too, though I never noticed the
gettimeofday problem).
For a temporary hack (*only* if upgrading is too much trouble) I'd
probably set tv_usec to zero and leave tv_sec alone (probably writing
some log message so you can tell if that's a possible cause of something
else breaking). Alternatively, write a loop to try gettimeofday up to
(say) five times until you get a valid result. Both of these hacks seem
unspeakably ugly though, upgrading doesn't. :-)
--
Ben Smithurst | PGP: 0x99392F7D
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