KB Article #70399

kernel Linux Customization

Problem

Modification of Linux kernel parameters for operating Transfer CFT is identical for x86, ia64 and S/390 architectures. The following indications are valid for all kernels of the 2.4x series supplied with your Linux distribution.


Resolution

Modify the global memory segment
To display the size of the global memory segment, enter the following command:
cat /proc/sys/kernel/shmmax



If the value is greater than 33554432, you do not have to change anything.



To modify this value perform one of the following procedures:



If your system supports sysctl, add the following line to your file /etc/sysctl.conf:
kernel.shmmax = 33554432
You must restart your system for the change to take effect.
Or



Type: echo 33554432 > /proc/sys/kernel/shmmax
This modification is overwritten when you restart Linux. Use this command in an rc.d script to ensure that the parameter value is taken into account when the system starts.
Or



Edit the file /usr/src/linux/include/linux/shm.h and change the value of the SHMMAX macro. You must rebuild the Linux kernel for this modification to take effect.
Customize message queues
You can retrieve the values for msgmax, msgmnb and msgmni using the commands:



cat /proc/sys/kernel/msgmax
cat /proc/sys/kernel/msgmnb
cat /proc/sys/kernel/msgmni
To operate Transfer CFT, the following values are sufficient:



msgmax = 8192
msgmnb = 8192
msgmni = 8192.
You can change these values:



If the kernel was generated via sysctl, by adding the following lines to the file etc/sysctl.conf. Remember that you must restart your system for this change to take effect.
kernel.mgmmax = 8192
kernel.msgmnb = 8192
kernel.msgmni = 8192





Or



Type the following:
echo 8192 > /proc/sys/kernel/msgmax
echo 8192 > /proc/sys/kernel/msgmnb
echo 8192 > /proc/sys/kernel/msgmni



This modification is overwritten when you restart Linux. Use this command in an rc.d script to make sure that the parameter values are taken into account when the system starts.



Or



By editing the file /usr/src/linux/include/linux/msg.h and changing the value of the macros MSGMAX, MSGMNB et MSGMNI. You must rebuild the Linux kernel for this modification to take effect.
Rebuild the kernel
When the parameters have been changed, the kernel must be regenerated.



To regenerate your kernel, refer to the manufacturer documentation.