[MUD-Dev] Introduction

Jeff Kesselman jeffk at tenetwork.com
Tue May 13 21:16:01 New Zealand Standard Time 1997


At 07:16 PM 5/13/97 PST8PDT, you wrote:
>>(FWIW, someone mentioned that process context switching was
>>expensive.  This is true, but your server is going to be switched out
>>anyways, as it's unlikely that nothing else is running on the machine
>>at all.)

As JL poinetd out its EQUALLY unlikely that you have 500 system processes.
But if you spwan a process per user you will get tehre pretty good.

Three snickers bar don't cost me much money... 500...

JK

>
>Context switching is cheap if it does not become a significant part of
>your total process expense (obviously).  Run a single process, or even
>just a couple/few processes and is stays cheap.  Start running one
>process for every connection or something else equally silly and of a
>sudden context switches start becoming a major fraction of the total
>expense of running your system.
>
>Wanna try something?
>
>Write a little program (shell script will do fine) that does nothing
>but print out numbers and delay a couple seconds every now and then. 
>Run a couple copies.  They'll run very nicely and very rapidly,  The
>price of context switching between the simultaneously executing copies
>is small.  Watch your CPU utilisation and it should stay quite low.
>
>Now start up 300 instances of this little trivial program and watch
>your system crawl into the drain.  Why?  The price of context
>switching between your programs suddenly became a significant
>percentage of the total work your CPU was doing.  (Graciously ignoring
>swap, RAM etc aspects that also chime in here).
>
>-- 
>J C Lawrence                           Internet: claw at null.net
>(Contractor)                           Internet: coder at ibm.net
>---------------(*)               Internet: clawrenc at cup.hp.com
>...Honorary Member Clan McFUD -- Teamer's Avenging Monolith...
>
>
>




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