X-Spam-Check-By: sourceware.org
Message-ID: <ba40711f0702111650u4c036648vc60947dd220b859b@mail.gmail.com>
Date: Sun, 11 Feb 2007 19:50:18 -0500
From: "Lev Bishop" <lev DOT bishop AT gmail DOT com>
To: cygwin AT cygwin DOT com
Subject: Re: strange bug in gettimeofday function
In-Reply-To: <20070211181603.GA4950@trixie.casa.cgf.cx>
MIME-Version: 1.0
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Content-Transfer-Encoding: 7bit
Content-Disposition: inline
References: <1562006224 DOT 20070211192014 AT gnu DOT org> 	 <20070211181603 DOT GA4950 AT trixie DOT casa DOT cgf DOT cx>
Mailing-List: contact cygwin-help AT cygwin DOT com; run by ezmlm
Precedence: bulk
List-Id: <cygwin.cygwin.com>
List-Unsubscribe: <mailto:cygwin-unsubscribe-archive-cygwin=delorie DOT com AT cygwin DOT com>
List-Subscribe: <mailto:cygwin-subscribe AT cygwin DOT com>
List-Archive: <http://sourceware.org/ml/cygwin/>
List-Post: <mailto:cygwin AT cygwin DOT com>
List-Help: <mailto:cygwin-help AT cygwin DOT com>, <http://sourceware.org/ml/#faqs>
Sender: cygwin-owner AT cygwin DOT com
Mail-Followup-To: cygwin AT cygwin DOT com
Delivered-To: mailing list cygwin AT cygwin DOT com

On 2/11/07, Christopher Faylor wrote:
> On Sun, Feb 11, 2007 at 07:20:14PM +0300, Andrew Makhorin wrote:
> >Hi,
> >
> >I detected a strange bug in the standard function gettimeofday.
> >It *sometimes* reports the time which being expressed as the integer
> >number of milliseconds is *less* than the time obtained *earlier* with
> >the same function.
> >
> >The expression 1000000 * tv.tv_sec + tv.tv_usec is calculated in
> >64-bit arithmetic, so overflow cannot happen. The negative difference
> >in the time values on two successive calls is about 100 milliseconds.
> >
> >cygcheck.out is attached.
>
> In cases like this a simple test case is really required.  If this is
> really true then calling gettimeofday in a loop should be enough to
> demonstrate the problem.

I have a hunch that it will be a good idea to have a look at what the
result of GetSystemTimeAdjustment() is on the machine exhibiting this
behaviour, at the time it exhibits this behaviour.

--
Unsubscribe info:      http://cygwin.com/ml/#unsubscribe-simple
Problem reports:       http://cygwin.com/problems.html
Documentation:         http://cygwin.com/docs.html
FAQ:                   http://cygwin.com/faq/