Red Hat ENTERPRISE LINUX 5 - VIRTUAL SERVER ADMINISTRATION, Руководство по установке

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Chapter 22. Additional Information for IBM System z Users
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• Activate the device.
Based on the type interface being added, issue an
ifup
command:
# ifup hsi n
# ifup eth n
# ifup tr n
22.7. Kernel-Related Information
Red Hat Enterprise Linux includes a modification to the way the Linux kernel timer interrupt is handled.
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 disabled.
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
Note
Disabling periodic timer interrupts can violate basic assumptions in system accounting
tools. If you notice a malfunction related to system accounting, verify that the malfunction
disappears if periodic timer interrupts are enabled, then submit a bug at
http://
bugzilla.redhat.com/bugzilla/
(for malfunctioning bundled tools), or inform the tool vendor
(for malfunctioning third-party tools).