On Jan 8,  6:24am, George Toft wrote:

> So if I issue the cat command as described, and compare that against 
> a ulimit command, I get the following discrepancy:
> [georgetoft@biff georgetoft]$ ulimit -a | grep files
> open files                  1024
> [georgetoft@biff georgetoft]$ cat /proc/sys/fs/file-max
> 4096
> [georgetoft@biff georgetoft]$
> 
> The number given by ulimit is the one that takes effect (243 virtual
> hosts * 4 log files per host = 979, plus a few other open files for
> mail, logs, login shells, etc is pretty close to 1024), so I'm 
> wondering what effect /proc/sys/fs/file-max has.  The write up you
> pointed me to seems to conflict with what I observed.
> 
> Any clarification would be appreciated.

The ulimit command specifies a per-process limit.  The value contained
in /proc/sys/fs/file-max is the overall limit for the entire system.

With the values that you cite above, it would only take four processes
to max out the limit contained in /proc/sys/fs/file-max.

For your application, it sounds to me like you need to increase your
per-process open file limit.  (You may need to increase the overall
system limit too.)  I notice that as root, I'm able to do 
``ulimit -n 2048'' and then ``ulimit -a'' actually shows that the limit
has been increased.

I've done some tests (using calls to pipe()) and have determined that
I'm able to create more than 1024 open files when I do this.  However,
it seems to me that not all functions implemented by glibc will
support more than 1024 files.  In particular, the select() function
relies on the fd_set data structure to know which file descriptors to
wait for.  It appears to me that you can't use this function for file
descriptor numbers past 1023.  In /usr/include/bits/types.h (which is
included by /usr/include/sys/types.h), I see the following:

    /* Number of descriptors that can fit in an `fd_set'.  */
    #define __FD_SETSIZE	1024

I think you're okay if your application uses poll() instead of
select() though.

Kevin


From Don Harrop <don@nis4u.com>  Tue Jan  9 00:46:02 2001
From: Don Harrop <don@nis4u.com> (Don Harrop)
Date: Mon, 8 Jan 2001 17:46:02 -0700 (MST)
Subject: fsck and fstab
Message-ID: <Pine.LNX.4.21.0101081742030.6646-100000@tech1.nis4u.com>

I remember either reading or finding some information a while back
regarding the mounging process at bootup.  After a certain number of
system restarts fsck is forced.  What file keeps track of this number?  Is
it the same file that you can adjust the how often fsck is forced?  I've
been trying to find it again and I guess my brain is toast.  It must be
the end of the day or something.. :-)

Don