Subject: Re: NetBSD is not Linux
To: Stephane St Hilaire <>
From: Matthias Buelow <>
List: netbsd-users
Date: 06/11/2001 23:06:13
Stephane St Hilaire writes:

>I'm not sure what is your point... Is 4090 processes an insufficient number
>? Does a program made up of one executable/two threads require more
>ressources and run slower than a program that forks itself up and uses twice
>the amount of memory ? Are you saying that threads are not useful in an OS
>and should never be a part of NetBSD ? 

The problem wojtek was probably hinting at is, since lignux maps
each user library thread onto one kernel process entry, running
applications which use many threads (like, several thousand[1]) is
prohibitive, from a resource consumption pov, and often simply not
possible, when the number of threads is larger than the max number
of proctable entries.
Normally, thread libraries multiplex many user threads onto a few
system threads so that problem is not so serious there.  This seems
not to be the case with the linuxthreads libraries, however.


[1] You might say applications with several thousand threads do
not exist?  Think of server applications that don't use the
poll(2)/select(2) mechanism for i/o multiplexing and instead use
a single thread per client connection.  Such a thing should be
fairly common in the Windoze "server" world, for example.  Also,
with the broader acceptance of Java[tm], there would be an increased
base of thread-hungry server applications.