'[Rxtx] High cpu use with no activity'

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List:       rxtx
Subject:    [Rxtx] High cpu use with no activity
From:       "Tivoli, Christopher" <Tivoli () pbworld ! com>
Date:       2005-01-13 15:50:08
Message-ID: 25D454F3DBD1AF46A718F761CB11ABE101857FF9 () nycmrmt1 ! corp ! pbwan ! net
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Hi Trent,

I'm attempting to run rxtx-2.1-6 under TRU-64 4.0G (don't ask!).  I'm
managing 18 channels but it appears rxtx is using ~50% of the CPU even
with no writes or pending reads.  The box is only 166 MHZ but should I
consider this normal?

Also, If you wouldn't mind entertaining a few questions from someone who
only knows enough to be dangerous.  In RXTXPort():

1) Why is there a usleep(20000) (almost) immediately after the select()?

2) Am I correct that report_serial_events() is called every 20ms whether
there's anything on the port or not?

3) Would there be any harm in removing the usleep and making the
select() timeout 20ms so I can then only call report_serial_events()
when (eis.ret > 0) instead of the current (eis.ret >= 0)?  

4) With TRU-64 how can I determine if I should have TIOCSERGETLSR or
TIOCGICOUNT defined or not?

Thanks for your hard work,

Chris Tivoli

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<P><FONT SIZE=2 FACE="Arial">Hi Trent,</FONT>
</P>

<P><FONT SIZE=2 FACE="Arial">I'm attempting to run rxtx-2.1-6 under TRU-64 4.0G \
(don't ask!).&nbsp; I'm managing 18 channels but it appears rxtx is using ~50% of the \
CPU even with no writes or pending reads.&nbsp; The box is only 166 MHZ but should I \
consider this normal?</FONT></P>

<P><FONT SIZE=2 FACE="Arial">Also, If you wouldn't mind entertaining a few questions \
from someone who only knows enough to be dangerous.&nbsp; In RXTXPort():</FONT></P>

<P><FONT SIZE=2 FACE="Arial">1) Why is there a usleep(20000) (almost) immediately \
after the select()?</FONT> </P>

<P><FONT SIZE=2 FACE="Arial">2) Am I correct that report_serial_events() is called \
every 20ms whether there's anything on the port or not?</FONT> </P>

<P><FONT SIZE=2 FACE="Arial">3) Would there be any harm in removing the usleep and \
making the select() timeout 20ms so I can then only call report_serial_events() when \
(eis.ret &gt; 0) instead of the current (eis.ret &gt;= 0)?&nbsp; </FONT></P>

<P><FONT SIZE=2 FACE="Arial">4) With TRU-64 how can I determine if I should have \
TIOCSERGETLSR or TIOCGICOUNT defined or not?</FONT> </P>

<P><FONT SIZE=2 FACE="Arial">Thanks for your hard work,</FONT>
</P>

<P><FONT SIZE=2 FACE="Arial">Chris Tivoli</FONT>
</P>

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