CPU usage of telnetd

[Jerry Toporek]

In article <10620 at amdcad.UUCP> phil at amdcad.UUCP (Phil Ngai) writes:
>There's a vendor who wants to sell me an ethernet interface that looks
>like a DMF serial interface. (actually, there's several of them) They
>claim telnetd uses a lot of resources. I was dubious but then I used
>the 'top' utility and saw a telnetd doing continous output at an
>effective rate of 9600 baud uses 20% of a 780.
>
>It sounds like the vendor is right. Any comments? Are there any
>implementations of telnetd which are more efficient or is this just
>inherent in the nature of the system?

Phil:

I don't know if you are referencing our product or not, but from the des-
cription you certainly might be.

If the telnet daemon is intended to extensively inspect both the input and
output streams, then resource utilization such as you describe might occur.
Our net terminal driver looks like a DMF only in the sense that it interfaces
with the VMS terminal class handler just like a DMF, or DZ, or whatever.  The
telnet daemon in this sort of setup is not required to do any input or output
processing, that is all left to the class handler.  In this case a good bit of
resource can be wasted passing off output to the telnet daemon to pass onn to
the net.  (This is what we were doing in our initial version.)  This can be
improved upon by arranging to pass data received by the terminal driver from
the class handler directly to the network driver.  (This is what we now do.
We still route keyboard input through the daemon, since there are a few things
we want to handle there, like urgent data.)  In this configuration, the test
you mention above, monitoring a continuous output to the net terminal, should
show resource utilization by the daemon of 0.

jt

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