Messages in this thread | | | Date | Mon, 2 Jun 2008 19:22:03 +0200 | From | Rodolfo Giometti <> | Subject | Re: LinuxPPS low-level IRQs timestamps & ldisc |
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On Mon, Jun 02, 2008 at 04:48:40PM +0100, Alan Cox wrote: > > I prefere avoid the if clause for getnstimeofday() since each > > instruction delay may decrease time precision, so: > > Why should everyone else pay the cost of the getnstimeofday they don't > need ? > > The single conditional check at the start won't make the slightest > material difference to your accuracy.
In the past we noticed that just moving up the getnstimeofday() of only one instruction, from:
port->icount.dcd++; getnstimeofday(&ts);
to:
getnstimeofday(&ts); port->icount.dcd++;
the time precision improved from 5ms to 2ms...
However, if you prefere that I add the if clause, I'll do it.
Thanks,
Rodolfo
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GNU/Linux Solutions e-mail: giometti@enneenne.com Linux Device Driver giometti@linux.it Embedded Systems phone: +39 349 2432127 UNIX programming skype: rodolfo.giometti
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