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Date:      Fri, 19 Jul 2002 08:06:05 +0100
From:      David Malone <dwmalone@maths.tcd.ie>
To:        Jeremy D'Hoinne <jeremy.dhoinne@netasq.com>
Cc:        freebsd-hackers@FreeBSD.org
Subject:   Re: select() behavior when system date changes precisions.
Message-ID:  <20020719070605.GA60918@walton.maths.tcd.ie>
In-Reply-To: <20020718175856.2a5dd923.jeremy.dhoinne@netasq.com>
References:  <20020718175856.2a5dd923.jeremy.dhoinne@netasq.com>

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On Thu, Jul 18, 2002 at 05:58:56PM +0200, Jeremy D'Hoinne wrote:
> I've forgottent to precise that servers involved use thread library
> (compilation with -pthread flag)

Ahhh - this may explain what you are seeing - I think that the
threaded library uses gettimeofday, which would see the time going
backwards. The non-threaded version of select uses a kernel
"getmicrouptime" call, which shouldn't have this problem.

It is possible a getuptime call might be useful for people implimenting
things like the threading library.

OTOH, there is usually no need to step the clock backwards on FreeBSD
after boot. Because get gettimeofday returns the time in UTC there
will be no jump for daylight savings. The only remaining problem
are leap seconds, which don't happen very often.

	David.

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