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HP-UX 11.31 PHKL_41700 warning

Created: 27 Dec 2011 • Updated: 03 Jan 2012
Nicolai's picture
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I have noticed a drop up to 2/3 in backup performance on HP-UX 11.31 systems where PHKL_41700 is installed.  A support case at HP provided the follwing information:

PHKL_41700 introduced behavior whereby on systems that do not enable high resolution timers, applications that use the select(2) system call as a timers may suffer performance degradation. If the performance degradation disappears after setting the kernel tunable:

hires_timeout_enable=1

Then the performance degradation observed is caused by the changes introduced in the select(2) system call code path provided by PHKL_41700.

This behavior is known to affect the performance of DataProtector, Quest Shareplex, Oracle SQL, Veritas Cluster Server, xntp (Network Time Protocol) and xterm(1) commands. Furthermore, any application that uses the select(2) system call with zero timeout and a value for nfd > 0 will experience this behavior.

To work around this behavior, set kernel tunable parameter hires_timeout_enable using:

kctune hires_timeout_enable=1

HP documentation for the hires_timeout_enable tunable kerne parameter can be found here.

To be updated as information arrives ...

Update:

The "kctune hires_timeout_enable" workaround seems to do it's job. The official fix is located in Patch PHKL_41967 (require reboot).