On Thu, Jul 17, 2003 at 11:54:09AM -0500, Austad, Jay wrote:
> > That's simply untrue, there are many IRC servers out there that handle
> > thousands of clients running on Linux, and have done so since 
> > the 2.2.x
> > kernels.
> 
> I've argued this before on this list.  :)  With FreeBSD, you just add
> -DFD_SETSIZE when you compile, and this works.  However, with linux, you
> cannot do this.  There is a hard limit of 1024 descriptors in FD_SET().
> Apparently, you can't just change it and recompile as it will break a bunch
> of things.  I would assume that these IRC servers are forking multiple
> copies or using poll() instead of select() (qmail uses select()).  
> 

They are not multithreaded, and they do not fork (beyond when you initially
start the server and it goes into daemon mode, and then the original copy exits)


mhallacy 16177  9.2  1.3 28704 27316 ?       S    14:49   0:24 ./ircd

lsof -p 16177 |grep IPv4 | wc -l
   1304

ulimit -a
core file size        (blocks, -c) 0
data seg size         (kbytes, -d) unlimited
file size             (blocks, -f) unlimited
max locked memory     (kbytes, -l) unlimited
max memory size       (kbytes, -m) unlimited
open files                    (-n) 8192
pipe size          (512 bytes, -p) 8
stack size            (kbytes, -s) 8192
cpu time             (seconds, -t) unlimited
max user processes            (-u) 7168
virtual memory        (kbytes, -v) unlimited


This is the undernet ircd daemon, with 1300 copies of energy mech running
(a simple irc bot) on the same system connecting to localhost.

For what it's worth, they can use both poll() and select(), perhaps qmail needs
to be *fixed* for use on high performance hardware instead of tossing more
and more hardware at it =)


-- 
Matthew S. Hallacy                            FUBAR, LART, BOFH Certified
http://www.poptix.net                           GPG public key 0x01938203

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