19.2K on a 3b1

Brian D. Botton botton at i88.isc.com
Fri Apr 5 15:49:39 AEST 1991

In article <1991Apr04.144939.587 at quest.UUCP> ssb at quest.UUCP (Scott Bertilson) writes:

  [ stuff deleted ]

>have to run the terminal manager under MGR.  Someone suggested that
>MGR was too CPU-intensive to run a terminal emulator, so my second
>test was to "Suspd" myself to another "wind.o" window and run the
>terminal emulator..which normally shuts down MGR and drops you into
>a shell in the window you left.  That worked just fine . . . . .

  Brad and I found out about this a couple of months ago, and Brad has
been too busy to really look into it.

  [ more stuff deleted ]

>  I don't know that much about the internals of MGR, but I
>am inclined strongly to believe that the only thing it is
>doing when "idle" but alive is calling "select".

  The select call does indeed seem to be the problem, but at least
you have source so you can investigate instead of speculate.

>						   I'm
>convinced that somewhere in "select" there is a long critical
>section run with interrupts blocked, but I can't figure out
>where it is.

  I'm sure Brad wouldn't mind it if you should happen to find the problem
and fix it.

>		The fact that Ethernet exhibits the same symptoms
>leads me to believe that this is an insurmountable problem
>inherent in applying the "select" wart to our SysV hog.  (I
>assume that BSD on VAXen solves it using the NETISR code,
>but I haven't had access to BSD kernel source for a number
>of years so I can't see how they make "select" work better.)

  The code for select was based on code from the person that did the
TCP/IP port and from the BSD 4.3 select code.

>I've wondered if one might be able to solve this problem by
>carefully applied optimizations to "select", but I don't know
>what part of the code to concentrate on and haven't had time
>to experiment until I figured out.

  You're not alone.  Good hunting.

     ...     ___	     ***
   _][_n_n___i_i ________  *******		Brian D. Botton
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