SUMMARY: What's a good value for maxusers...

From: John R. Neil (
Date: Fri Sep 25 1992 - 21:54:27 CDT

I would like to thank all those who gave responses to my inquiry about a
good value for maxusers in the kernel configuration of our IPX. Based on
what those responses were, I chose to set the value at 64. While our
current load does not necessitate that level, we are expecting to add a
few X-terminals to that machine and will, no doubt, increase the amount
of processes required. By setting a value of 64, we now have a little over
1000 available processes. Even with this increase, we have yet to top
300. However, that is more than we had available before.

Here are the responses I received on this questions (edited slightly to
save a bit on band-width):

Respose 1 from

how many users are you expecting at a time?

as i recall, the default is 8 users. each separate window also counts
(rule of thumb) as a user as well. so if you have 3 users (r)logged in,
each running 3 windows, you should figure 9 users.

item: GET MORE RAM! it's cheap, and will solve MANY MANY MANY problems.

after that, bumping up maxusers to say, 32, won't hurt anything. actually,
bumping it to 128 won't hurt anything either. all you're doing is increasing
the kernel size (buffers, etc), which isn't going to get HUGE anyway.


Respose 2 from (Mike Rembis 6259)

Typical MAXUSERS are:

        Desktop = 64
        Server (490) = 128

This, from my Sun rep.

Reponse 3 from (Nathan Hess)

I would recommend at least 32...


Response 4 from Lawson A S <>

I believe it's something like 8 processes per maxuser unit, so that
maxusers=4 would allow 32 processes before running out.
Tony lawson
Department of Computer science
University of Essex
Wivenhoe Park
Essex C04 3SQ

Response 5 from ups!upstage!glenn@fourx.Aus.Sun.COM (Glenn Satchell)

Hi John,

It depends on your usage pattern... The golden rule is to increment it
a bit and test. I assume that you have either 8 or 16 currently (8 is
the default for a generic kernel). Just try doubling it and see how
you go. If you are still running out then double it again. Remember
that for each increase the kernel will reserve more memory for its
pointers, etc, so that you will start to swap a lot more. I wouldn't
suggest you go past 64 though without increasing your memory to at
least 32M.

| Glenn Satchell | "The answer is no, |
| Uniq Professional Services Pty Ltd | and I'll negotiate |
| "Sun Accredited System Consultants" | from there." |
| ups! | -my boss |

Response 6 from (Phil Blanchfield)

This is what I use on a 670 and SS2 systems, no problems for 6 months or so.
(This I dug up from a former sun-managers summary)

From: Mike Raffety <>
You can't use 256 maxusers ... there's some kernel ints wrapping around
as a result ... using AnswerBook, and searching for "maxusers", I
immediately found a table in the 4.1.2 Release Manual, section 8.3,
page 8-6:

----- begin included message -----

For best performance, you want to set the manusers value in the kernel
configuration file to a high value. Use the formula described below to
determine the maxusers value, but be aware of the following limitations;
if you exceed these values, your kernel may not boot.

Table 8-4: Maximum maxusers Values for Sun-4, Sun-4c, Sun-4m

Arch <=64MB 128MB 640MB 2.5GB RAM
sun4 225 225 NA NA
sun4c 225 225 NA NA
sun4m 185 180 155 45

Note that the maximum maxusers value for a SPARCsystem 600MP system is
between 45 adn 185, depending on the system configuration -- the more
memory, the lower the maxusers value. These maxusers values correspond
to 1024 and 3253 processes, respectively.

----- end included message -----

There's more on how to calculate a good maxusers value.

Response 7 from (Celeste Stokely)

It depends on what you're doing on the machine. I run Frame, netnews, openwin,
and lots of other fairly large progesses. I run w/ MAXUSERS=64. I also
have 24MB of memory and 73MB of swap.

Hope this helps,

..Celeste Stokely

Response 8 from David Holmes <>

With "several" users I would probably go with a maxusers of 16.
Do post a summary though as it would be interesting to see what
others think about this magic.


Response 9 from (Martin Kelly)

Hello John,

Why don't you put in more memory and increase maxusers to about 128 ...

- martin

Response 10 from Mike Raffety <>

What's your current maxusers value? How many users do you have logged
in at any given time (i.e., what's "several")? How much memory do you
have (this affects the choice of maxuers)? The default number of
maxuers is 8. If you're still at 8, then try 16. If that's not
enough, then try 32 ... This is the sort of thing that's highly host
dependent, and easy to experiment with.

Please be sure to summarize back to the list; thanks.

John Neil, Graduate Teaching Assistant e-mail:
Mathematics Department NeXTMail:
Portland State University

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