Red Hat ENTERPRISE LINUX AS 2.1 - Przewodnik Instalacji Pobierz pdf (Strona 79)

Appendix F. Additional Information for S/390 and zSeries Users 71

• Create a conﬁguration script.

Create a ﬁle in /etc/sysconfig/network-scripts/ with a name like the following:

ifcfg-iucv<n>

The ﬁle should look like this:

/etc/sysconfig/network-scripts/ifcfg-iucv0

# IBM IUCV

DEVICE=iucv0

BOOTPROTO=static

IPADDR=192.168.70.136

GATEWAY=172.16.70.136

NETMASK=255.255.255.255

ONBOOT=yes

NETTYPE=iucv

PEERID=TCPIP

TYPE=IUCV

• Activate the device.

Based on the type interface being added, issue an ifup command like the following:

# ifup iucv<n>

F.7. Kernel-Related Information

Red Hat Enterprise Linux includes a modiﬁcation to the way the Linux kernel timer interrupt is han-

dled. Normally, a hardware timer is set to generate periodic interrupts at a ﬁxed rate (100 times a

second for most architectures). These periodic timer interrupts are used by the kernel to schedule

various internal housekeeping tasks, such as process scheduling, accounting, and maintaining system

uptime.

While a timer-based approach works well for a system environment where only one copy of the kernel

is running, it can cause additional overhead when many copies of the kernel are running on a single

system (for example, as z/VM(R) guests). In these cases, having thousands of copies of the kernel

each generating interrupts many times a second can result in excessive system overhead.

Therefore, Red Hat Enterprise Linux now includes the ability to turn off periodic timer interrupts.

This is done through the /proc/ ﬁle system. To disable periodic timer interrupts, issue the following

command:

echo "0" > /proc/sys/kernel/hz_timer

To enable periodic timer interrupts, issue the following command:

echo "1" > /proc/sys/kernel/hz_timer

By default, periodic timer interrupts are enabled.

Periodic timer interrupt states can also be set at boot-time; to do so, add the following line to

/etc/sysctl.conf to disable periodic timer interrupts:

kernel.hz_timer = 0

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Red Hat ENTERPRISE LINUX AS 2.1 - Przewodnik Instalacji Strona 79