Date: Mon, 2 Jun 2008 13:09:16 -0400
To: Rodolfo Giometti <giometti@enneenne.com>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>,
       Andrew Morton <akpm@linux-foundation.org>, linux-kernel@vger.kernel.org
Subject: Re: LinuxPPS low-level IRQs timestamps & ldisc
Message-ID: <20080602170916.GD16164@csclub.uwaterloo.ca>
References: <20080601161510.GA26854@enneenne.com> <20080602075113.60d0fdf8@core> <20080602092551.GC26854@enneenne.com> <20080602150257.54692f35@core> <20080602145603.GG26854@enneenne.com>
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From: lsorense@csclub.uwaterloo.ca (Lennart Sorensen)
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On Mon, Jun 02, 2008 at 04:56:03PM +0200, Rodolfo Giometti wrote:
> I prefere avoid the if clause for getnstimeofday() since each
> instruction delay may decrease time precision, so:

Not if the delay is always constant.  That you can adjust for.  You
already have to adjust for cable length and such for your GPS, so
adjusting for a fixed delay for a conditional is no big deal.

Of course if you have to check of the DCD changed, that may not be
constant.  A check for whether this device currently has anyone that
wants the timestamp though should be a constant time.

-- 
Len Sorensen
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