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<p class=MsoNormal><font size=2 color=navy face=Arial><span lang=EN-CA
style='font-size:10.0pt;font-family:Arial;color:navy'>Hi to all!<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span lang=EN-CA
style='font-size:10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span lang=EN-CA
style='font-size:10.0pt;font-family:Arial;color:navy'>I did some more search
and it appears that Mr Robert Supnik did modify in Oct 2006 the<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span lang=EN-CA
style='font-size:10.0pt;font-family:Arial;color:navy'>files PDP11/pdp11_xq.c
and pdp11_xu.c to synchronize the polling of the Ethernet interface with<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span lang=EN-CA
style='font-size:10.0pt;font-family:Arial;color:navy'>the timer clock.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span lang=EN-CA
style='font-size:10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span lang=EN-CA
style='font-size:10.0pt;font-family:Arial;color:navy'>This modification makes
the polling rate totally unused. Even if one sets the polling rate to another
value than the default of 100 polls per second, it stays at the default rate. This
change of behaviour is not documented. Further, if one do a set xq poll=1300
and then a show xq, the output indicates correctly the new polling rate, but
that rate is simply not taken into account, and simh continues to poll the
reception of Ethernet packets at it’s default rate of 100 polls per
second.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span lang=EN-CA
style='font-size:10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span lang=EN-CA
style='font-size:10.0pt;font-family:Arial;color:navy'>To fall back to the
previous setting, I did copy those two files from the sources of version 3.6-1
of simh, into the same files of version 3.7-3, and then recompile.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span lang=EN-CA
style='font-size:10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span lang=EN-CA
style='font-size:10.0pt;font-family:Arial;color:navy'>After that, I did some
tests, and it appears that for 100Mbps Ethernet, the optimal polling rate on
our setup is of 1300 polls per second.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span lang=EN-CA
style='font-size:10.0pt;font-family:Arial;color:navy'>When I do a monitor
system, I obtain a 2300 buffered IO rate per second, from a 800 buffered I/O
rate per second.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span lang=EN-CA
style='font-size:10.0pt;font-family:Arial;color:navy'>That modification and
tuning of 1300 polls per second gave us a 300% increase in Ethernet throughput!<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span lang=EN-CA
style='font-size:10.0pt;font-family:Arial;color:navy'>Also, I did see by
running PT_VAX.EXE that there is a slight performance penalty when I rise at
1300 polls per second the rate, but that penalty is of the order of passing
from 25.0 VUPS to 23.9 VUPS, for the performance gain of 300% Ethernet I/O.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span lang=EN-CA
style='font-size:10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span lang=EN-CA
style='font-size:10.0pt;font-family:Arial;color:navy'>So, for my part, this
case is closed, but I would appreciate any comments about further optimisation
of the Ethernet driving of simh.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span lang=EN-CA
style='font-size:10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span lang=EN-CA
style='font-size:10.0pt;font-family:Arial;color:navy'>Thanks,<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span lang=EN-CA
style='font-size:10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=MsoNormal><st1:PersonName ProductID="Francois Boucher" w:st="on"><font
size=2 color=navy face=Arial><span lang=EN-CA style='font-size:10.0pt;
font-family:Arial;color:navy'>Francois Boucher</span></font></st1:PersonName><font
size=2 color=navy face=Arial><span lang=EN-CA style='font-size:10.0pt;
font-family:Arial;color:navy'><o:p></o:p></span></font></p>
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