Cannot create more than 32K threads?

Hi,

I was using the 'thread-limit' program from
http://people.redhat.com/alikins/tuning_utils/thread-limit.c to test the
number of threads it could create.  It seems that it was always hitting
some limit at 32K threads (cannot create thread 32762, to be exact). The
error is ENOMEM.  Here's the kernel/ulimit settings,

/proc/sys/kernel/pid_max 300000
/proc/sys/kernel/threads-max 100000

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) 100000
pipe size          (512 bytes, -p) 8
stack size            (kbytes, -s) 32
cpu time             (seconds, -t) unlimited
max user processes            (-u) 100000
virtual memory        (kbytes, -v) unlimited

It gave the same result on both a Debian 3 box with NPTL 0.56 compiled
with gcc 3.4 CVS and GlibC CVS, kernel 2.5.70, and vanilla Redhat 9.

I know I must be missing something because 100K threads with NPTL was
reported.  Thanks.

-- 
Feng Zhou
Graduate Student,
CS Division, U.C. Berkeley
http://www.cs.berkeley.edu/~zf/