Solaris: Increasing the Maximum Processes per User ID

This blog post attempts to show the steps involved {with an example} in increasing the maximum processes allowed per user id on Solaris.

Steps

• Examine the current limit.
  

  
  % ulimit -a
  core file size          (blocks, -c) unlimited
  data seg size           (kbytes, -d) unlimited
  file size               (blocks, -f) unlimited
  open files                      (-n) 256
  pipe size            (512 bytes, -p) 10
  stack size              (kbytes, -s) 8480
  cpu time               (seconds, -t) unlimited
  max user processes              (-u) 9989
  virtual memory          (kbytes, -v) unlimited
  
  # echo maxuprc/D | adb -k
  physmem 5f75e
  maxuprc:
  maxuprc:        9989
  
  # sysdef | grep v_maxup
      9989        maximum processes per user id (v.v_maxup)
  
  

  
  
  On Solaris:
  
         max_nprocs = (10 + 16 * maxusers)
         maxuprc = (max_nprocs - 5)
  
  Where:
  
  max_nprocs = Total number of system wide processes
  
  maxuprc = Total number of processes a non-root user can have occupying a process table slot at any point in time
  
  maxusers is a tunable parameter at the kernel level that is by default set to the lesser of the amount of memory in Mbytes or 2048. Range: 1 to 2048, based on physical memory if not set in the /etc/system file; and 1 to 4096, if set in the /etc/system file.
  
  
  Proceeding with the same example:
  
  

  
  # echo maxusers/D | adb -k
  physmem 5f75e
  maxusers:
  maxusers:       624
  
  

  
  Therefore, maxuprc = (10 + (16 * 624) - 5) = 9989.
  
  
• If rebooting the system is not an option, dynamically increase the maximum user processes limit as shown in the example. The following example increases the limit to 20,000.
  
  

  
  # adb -kw
  physmem 5f75e
  maxuprc/D  <-- type this line
  maxuprc:
  maxuprc:        9989           
  v+0x1c/W0x4e20             <-- type this line. 0x4e20 is the hexa-decimal equivalent of 20,000
  v+0x1c:         0x2705          =       0x4e20
  $q         <-- type this to quit adb
  
  

  
  Check the maximum user processes limit one more time.
  

  
  % ulimit -a | grep processes
  max user processes              (-u) 20000
  
  % sysdef | grep v_maxup
     20000        maximum processes per user id (v.v_maxup)
  
  

  
  Note:
  Even though the maxuprc gets updated in the system, abd still shows the old value that it picked up during the system boot up process.
  
  
• If the system can be rebooted or if you want the new maxuprc value to be presistent across multiple reboots, add the following line to /etc/system.
  
         set maxuprc = <DesiredNumber>

Alternatively increase maxusers from the current value by setting set maxusers = <DesiredMbytes> in /etc/system. Then the maximum number of processes on the system will be derived from the maxusers.

Check Process-Sizing Parameters section of Solaris Tunable Parameters Reference Manual for more.

Reference:
Sunsolve Document 202586: How is the maximum size of the process table determined?
Solaris kernel tunables
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