From: Baran YURDAGUL (barany@netas.com.tr)
Date: Thu Jun 26 2003 - 02:00:57 EDT
fyi!
attached mail follows:
Hewlett-Packard
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HP IT RESOURCE CENTER
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Patch PHKL_25475 has a new warning
Dear BARAN YURDAGUL,
Hewlett-Packard has issued a new warning for the following patch:
PHKL_25475 : s700_800 11.00 PM cumulative patch
Please read the "Warning Description" below to determine whether it is
necessary for you take any actions.
Warning Description:
03/06/23 - This Critical Warning has been issued by HP.
- With PHKL_27089 or superseding patches installed, customers
have experienced a severe performance problem with the kernel
scheduling algorithm within the idle() loop of the Fair
Share Scheduler (FSS) used by the Process Resource Manager
(PRM) and WorkLoad Manager (WLM) applications. If either
application is enabled on a system, system performance
degrades dramatically in some cases.
- Performance degradation of 3 to 4 times for a single job has
been observed. Also, ServiceGuard nodes have experienced a
TOC due to this behavior.
- The problem has only been seen at customer sites on high end
systems containing more than 16 CPUs. However due to the
nature of the problem, it may impact any size system
especially a system with a heavy load on a few processors
with many other processors idle.
- The behavior increases with the number of processors that
are currently idle. Therefore, a system that continuously
keeps all CPUs busy may not observe the behavior.
- Additional information on this issue may be found in SR
8606311958 (JAGae74778).
- This behavior is also exhibited with superseding patches
PHKL_27351, PHKL_27510, PHKL_27813, PHKL_27770, PHKL_28152,
and PHKL_28202.
- The source of the problem was actually introduced in
PHKL_21111. Therefore it is possible that any of these
patches is exposed to this behavior: PHKL_21111, PHKL_21832,
PHKL_23180, PHKL_23408, PHKL_23617, PHKL_24502, PHKL_24753,
PHKL_24734, PHKL_24943, PHKL_25475, PHKL_25999, PHKL_26059,
PHKL_27089, PHKL_27351, PHKL_27510, PHKL_27813, PHKL_27770,
PHKL_28152, and PHKL_28202. As a result, HP is issuing Patch
Warnings for all these patches. However, customers have only
experienced the problem on PHKL_27089 and later. This is
believed to be due to the recompilation of the files
containing the original change.
- To verify if a system experiencing performance problems is
due to this behavior, PRM and WLM can be temporarily
disabled by issuing the following commands as root:
PRM: /opt/prm/bin/prmconfig -r
WLM: /sbin/init.d/wlm stop
- If disabling PRM and WLM verified that the system is the
experiencing the behavior, then HP recommends removing these
patches from systems and install PHKL_24502 to use either PRM
or WLM.
- PHKL_24502 also contains the code path that has been
demonstrated to lead to this behavior. However, PHKL_24502
has not been shown to cause this same behavior with PRM or
WLM on customer systems.
- PHKL_25475 is included in the following Support Plus Patch
Bundles:
Mar 2002: QPK1100,B.11.00.56.5
If you have any questions, please contact the HP Response Center.
Thank you -
HP Patch team
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