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The On Demand Timer Patch is included in the current Novell/SUSE
SLES 9 and SLES 8 distributions. Due to some issues you should
upgrade to the latest available kernel version provided by
Novell/SUSE, especially for Novell/SUSE SLES 8 to SP3. Newer
distributions should contain the recommended version of the
On Demand Timer Patch.
Red Hat RHEL3 Update1 and higher and RHEL4 also include the
On Demand Timer patch. The RHEL4 Installation Guide refers
to the On demand timer patch in Appendix F.7. 'Kernel-Related
Information'.
You can always obtain the recommended level of the Timer
Patch for the IBM code drops. Look for "On demand timer" in
the following kernel streams at the following URL
Linux on System z
- "August 2001 stream" - Kernel 2.4.7 and Kernel 2.4.17
- "June 2003 stream" - Kernel 2.4.21
- "April 2004 stream" - Kernel 2.6.5
Or look if the distributor of your Linux offers such patches
and updates.
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The Novell/SUSE SLES 8 and SLES 9 distributions deliver the
Linux kernel pre-configured with the ability to turn off periodic
timer interrupts.
Red Hat RHEL3 and RHEL4 distributions provide the ability
to turn off periodic timer interrupts by default, too.
The ability can be switched off by changing the kernel config
option CONFIG_NO_IDLE_HZ=n and a kernel recompile.
Alternatively the On Demand Timer Patch can be activated and
deactivated with the following convenient method. Use the
sysctl command to switch the setting in the proc
file system:
'sysctl -w kernel.hz_timer=1' enables the
100 Hz timer. The On Demand Timer Patch is deactivated.
'sysctl -w kernel.hz_timer=0' disables the
100 Hz timer. The On Demand Timer Patch is activated.
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