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Date:	Thu, 14 Feb 2008 16:52:01 -0600
From:	Brian Ford <Brian DOT Ford AT FlightSafety DOT com>
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Subject:	RE: Perl with SerialPort
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On Wed, 13 Feb 2008, Dave Korn wrote:

> On 13 February 2008 22:59, Dave Korn wrote:
>
> > On 13 February 2008 22:46, Dave Korn wrote:
> >
> > t/01timing.............NOK 7#     Failed test (t/01timing.t at line 33)
> > # then: 207441765 now: 207443905 diff: 2140
> > # Looks like you failed 1 test of 7.
> > t/01timing.............dubious
>
>   That diff is absolutely reliably consistently 2140 for me.  I'd
> speculate that maybe the cygwin signal emulation requires a context
> switch or two, to or away from the signal processing thread, and so
> we're seeing an extra quantum or two of constant overhead for systematic
> reasons.

Yep, two.  The minimum quantum on NT based OSes is 1024.  See this
thread for support of your hypothesis:

http://cygwin.com/ml/cygwin-developers/2007-10/msg00040.html

-- 
Brian Ford
Lead Realtime Software Engineer
VITAL - Visual Simulation Systems
FlightSafety International
the best safety device in any aircraft is a well-trained crew...

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