limitiation on memory allocation

Chuck Swiger cswiger at
Mon Mar 12 19:14:03 UTC 2007

On Mar 12, 2007, at 12:02 PM, Dima Sorkin wrote:
> Something is probably wrong.
> kern.dfldsiz on my machine does not influence.

I don't believe you can change that value after the system has  
booted-- you have to set it either in the kernel's config file, or  
in /boot/loader.conf, for this to actually take effect.

> I.e. after booting I run
> $ limits
> and it shows me the old 500M.
> Now, a point about 'maxdsiz'= 3.0-3.5G instead of 4G - this one I  
> must check.
> I tried 3.9G   :)

Try using 3GB, agreed.

Also, please note that the dftdsiz keyword affects the "hard" limit,  
not the "soft" limit...your shell might well have 500MB "soft" dsize  
limit by default, but would permit you to change that upward to the  
maximum set by the "hard" limit once you've changed that value.

See "man getrlimit":

      A resource limit is specified as a soft limit and a hard  
limit.  When a
      soft limit is exceeded a process may receive a signal (for  
example, if
      the cpu time or file size is exceeded), but it will be allowed  
to con-
      tinue execution until it reaches the hard limit (or modifies  
its resource
      limit).  The rlimit structure is used to specify the hard and  
soft limits
      on a resource,

            struct rlimit {
                    rlim_t  rlim_cur;       /* current (soft) limit */
                    rlim_t  rlim_max;       /* maximum value for  
rlim_cur */

      Only the super-user may raise the maximum limits.  Other users  
may only
      alter rlim_cur within the range from 0 to rlim_max or  
      lower rlim_max.


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