Setting per-user kernel parameters for parallel jobs (AIX)

Per-user kernel parameters ensure that users who run parallel jobs have sufficient resources. Use the chuser command to set appropriate values.

About this task

The following table describes the parameters that control memory resources and recommends a value for each parameter. Complete the following steps for each user on each processing node in your parallel environment.
Table 1. Per-user kernel parameter values
Parameter Description Value
fsize The largest file that a user can create. 2 GB minus 512 bytes (4,194,303 512-byte blocks). For no limit, specify -1.
data The largest data segment, or heap, that a program can have. 128 MB (262,144 512-byte blocks) or more. For no limit, specify -1.
stack The largest stack that a program can have. 32 MB (65,536 512-byte blocks) or more.
rss The maximum amount of physical memory that a user process can use. 64 MB (131,072 512-byte blocks) or more.

Procedure

  1. Run the following command to determine the value of the memory size parameters for a user:
    /usr/sbin/lsuser -f user_name
    
    This command displays various parameters, including fsize, data, stack, and rss. For example:
    fsize=2097151 data=262144 stack=65536 rss=131072
    

    These numbers represent the number of 512-byte blocks.

  2. Log in as the root user.
  3. Set the parameters for each user as defined by the values in Table 1.
    The command has the form:
    /usr/sbin/chuser param=value user_name

    For example:

    /usr/sbin/chuser fsize=4194303 operator2
    /usr/sbin/chuser data=262144 operator2
    /usr/sbin/chuser stack=65536 operator2
    /usr/sbin/chuser rss=131072 operator2
    
  4. In an AIX® cluster, you can use the dsh command to set the kernel parameters on all cluster nodes. This command must be issued from the control workstation.
    dsh -a chuser param=value user_name
    

What to do next

Users whose per-user kernel parameters have changed must log out and log in again for the changes to take effect.