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Date:Mon Feb 7 17:38:16 2003 
Subject:(forwarded for Brian Logan) Poplog timers ... 
From:A . Sloman 
Volume-ID:1030207.01 

Non-member submission from [Brian Logan <bsl@cs.nott.ac.uk>]

I have been trying to write some procedures to time the execution of Poplog
code.

systime has fairly poor resolution (1/100th of a second), so I happily wrote
some timing procedures using sys_timer and trap procedures.  This didn't
work, and on closer reading of REF TIMES I discovered that the maximum
resolution of the asynchronous trap procedures created by sys_time is also
1/100th of a second.

usecs_or_false -> sys_timer(ast_p, flags)
usecs_or_false -> sys_timer(ast_p)
        This  procedure  and  its  updater  provide  multiple  real   or
        `virtual'  interval  timers,  each  attached  to  a   particular
        asynchronous trap procedure ast_p that  gets run when the  timer
        expires.

and then ...

        usecs may  be  a  biginteger, the  largest  time  allowed  being
        pop_max_int seconds plus 999999  microseconds (i.e. the  seconds
        part of usecs must be within the range of a simple integer). The
        smallest time allowed is 0, but assigning a non-zero time  value
        smaller than the resolution of the system clock sets a timer for
        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
        that resolution (e.g. 1/100th second on VAXen and Sun-4 systems,
        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
        1/50th sec on MC68000  systems, etc). A  zero time value  causes
        the timer to expire immediately.

which is what seems to happen.  When I created timers with what I thought
was microsecond resolution, I was surprised how fast my programs seemed to
be running (based on the number of timer ticks).  When scaled four orders of
magnitude, things made more sense.

Is there any way to get better than 1/00th of a second resolution timing in
Poplog?

Thanks


-- Brian

  Brian Logan,  School of Computer Science & IT, University of Nottingham
 Email: bsl@cs.nott.ac.uk,  Phone: +44 115 846 6509, Fax: +44 115 951 4254