*BSD News Article 69239


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From: dwatson@stout.entertain.com (Darryl Watson)
Newsgroups: comp.unix.bsd.bsdi.misc
Subject: MAX_USERS
Date: 23 May 1996 12:07:52 -0600
Organization: ABWAM, Inc., full service ISP, voice: 1+ 303 730-6050
Lines: 37
Message-ID: <4o29ho$1q9@stout.entertain.com>
NNTP-Posting-Host: stout.entertain.com


Hi all!

I have BSDI 2.0 with patches.

Our main server is quite busy with dialups through a Digiboard, primary 
nameservice, Apache httpd, and ftp service.  Right now, my kernel is set 
with MAX_USERS=64, and we typically have 25-30 users telnetted or dialed 
into the server.  In addition, we usually have at least 10 ftp sessions 
going at any time.

Lately, as our ftp traffic has increased, our server will occasionally 
start failing to serve POP requests, new telnet or ftp sessions, and 
other inetd services.  Inetd goes into runaway mode, and the syslog 
reports that inetd can't create any new processes, or there are too many 
files open.

My understanding is that the MAX_USERS kernel parameter controls more 
than the max number of users you can have logged in, but also gives the 
kernel hints as to how many files can be open on the system, how many 
processes can be created, etc.

Questions:  Will raising the MAX_USERS parameter from 64 to, say, 96 tend 
to get rid of the inetd race situation?  Is there a practical maximum on 
the MAX_USERS parameter?  Am I messing with a parameter that could 
seriously affect the performance of the system in mysterious ways?  Am I 
on target in my analysis of what the inetd race problem is caused by?

Any info appreciated!  I won't be able to read netnews for about a week, 
so please email dwatson@abwam.com with suggestions.

Thanks!

P.S.:  We are preparing to increase RAM on the system from 32megs to at 
least 64megs.  We've got plenty of swap space (200 megs or so!) so we 
expect better performance, but maybe putting MAX_USERS at 96 will require 
us to do the memory upgrade first, practicially speaking...