Re: maximum number of processes on kernel 2.4.x
I believe I have found a fix. I'm not sure where the RLIMIT_NPROC
value of 256 was coming from, but it can be changed by creating an
initscript (5) file on your system and setting the various limits
through there. Here's the new script from my system:
#
# initscript Executed by init(8) for every program it
# wants to spawn like this:
#
# /bin/sh /etc/initscript <id> <level> <action> <process>
#
ulimit -Hu 1024
ulimit -Su 512
# Execute the program.
eval exec "$4"
<--- (cut here, insert tab a into slot b)
Also, it looks like ssh was setting its own limits via pam. Oddly
enough, it also was setting RLIMIT_NPROC to 256. On Debian, this can
be changed in /etc/security/limits.conf.
Thanks for the help, Russell. I'd probably still be looking through
the kernel sources if I hadn't asked! =)
Wayne
--
Wayne A. Tucker - wtucker@donobi.com
Network Engineer, Donobi Inc.
On Mon, Mar 11, 2002 at 06:58:50PM -0800, Wayne Tucker wrote:
> On Tue, Mar 12, 2002 at 02:52:36AM +0100, Russell Coker wrote:
> > On Tue, 12 Mar 2002 02:33, Wayne Tucker wrote:
> > > > I guess that you have some problem related to ulimit...
> > >
> > > [snip]
> > >
> > > Is the "default" number of processes allowed by ulimit/setrlimit
> > > determined in the kernel, or is it being set from somewhere in the
> > > init scripts? Are resource limits inherited from the parent process,
> > > and can the default for daemons be changed somewhere in the init
> > > process so that they can be effective for daemon processes that start
> > > on bootup? The system does not have any users other than admins, so
> > > for our purposes it would be safe for us to have RLIMIT_NPROC set to
> > > something higher such as 512.
> >
> > I think that generally ulimit is not set in init scripts. However some init
> > scripts may end up sourcing /etc/profile (this is not a good idea), and
> > people often put ulimit commands in /etc/profile...
> >
> > The kernel definately doesn't put any significant limits in.
> >
> > Are you certain that it's a limit on the number of processes? Or might it be
> > some other limit that hits in when you have 256 processes?
> >
> > Check in /proc/sys/fs and see if the first field in file-nr is near the value
> > of file-max. Also do the same check for inode-max if it exists.
>
>
> The limit of 256 is coming from the `ulimit -s` command (bash). Just
> as a test, I also threw together a program to call getrlimit and
> display the result. Here's what I get:
>
> wayne@ironman:~$ cat /proc/version
> Linux version 2.4.17 (root@ironman) (gcc version 2.95.4 20011006 (Debian prerelease)) #1 Wed Jan 2 21:55:45 PST 2002
> wayne@ironman:~$ ./showrlimit
> cur: 256 max: 4294967295
>
> (now I really understand what you mwant when you said that my system
> would be dead long before it got there ;)
>
> I thought that this may have been coming from somewhere in bash, so I
> set up another account using tcsh, but I get the same result. I also
> ran an strace on bash, but I don't see any getrlimit calls in there.
>
> The system is running woody, and most of the init scripts are
> untouched. Interestingly enough, this is what I get on a system that
> is running potato with (Adrian?) Bunk's 2.4-series kernel packages:
>
> groucho:~$ cat /proc/version
> Linux version 2.4.14 (root@ironman) (gcc version 2.95.4 20011006 (Debian prerelease)) #1 Fri Nov 9 10:44:55 PST 2001
> groucho:~$ ./showrlimit
> cur: 2038 max: 2038
>
> It doesn't seem to be a kernel issue, either, as I this is what I get
> on another woody system:
>
> harpo:~$ cat /proc/version
> Linux version 2.4.14 (root@ironman) (gcc version 2.95.4 20011006 (Debian prerelease)) #1 Fri Nov 9 10:44:55 PST 2001
> harpo:~$ ./showrlimit
> cur: 256 max: 4294967295
>
> The hardware in these last 2 machines is virtually identical, with the
> exception of the latter one having a larger hard drive.
>
>
> If I do a ulimit -n 1024 and then su to another account, RLIMIT_NPROC
> is set back to 256. I'm trying to figure out how to run strace on the
> su session, but I can't get it to take the password.
>
> Here's the code that I used to call getrlimit:
>
> #include <sys/time.h>
> #include <sys/resource.h>
> #include <unistd.h>
> #include <stdio.h>
>
> int main(void)
> {
> struct rlimit rlimit_cur;
>
> getrlimit(RLIMIT_NPROC, &rlimit_cur);
> printf("cur: %lu max: %lu\n", rlimit_cur.rlim_cur, rlimit_cur.rlim_max);
> return(0);
> }
>
>
> Any thoughts?
>
> Many thanks,
>
> Wayne
>
>
> --
> Wayne A. Tucker - wtucker@donobi.com
> Network Engineer, Donobi Inc.
>
>
>
> --
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