topic Base_pagesize kernel parameter in Operating System - HP-UX

Base_pagesize kernel parameter

wvsa — Thu, 11 Feb 2010 17:27:21 GMT

Once again good morning;

We are running Oracle EBS 11.5.10 with a 10gr2 database on a rx6600 server running 11iv3 release5. I have come across the base_pagesize tunable parameter and it appears this could be a performance boost. My question is had anyone out there changed this value for 10gr2. If so what value did you use?

Thank you for responses.

Norm

Re: Base_pagesize kernel parameter

WayneHP — Thu, 11 Feb 2010 18:21:08 GMT

This docs explains it.

Carefull if you use Java and there are other patches required.

See note at end on Oracle.

http://docs.hp.com/en/14670/ENW-TBPS-TW.pdf

Re: Base_pagesize kernel parameter

wvsa — Thu, 11 Feb 2010 19:49:37 GMT

Wayne;

Thank you for the doc. Already have read the doc and already ran into the problem with Java. Got past the Java problem. The document does not provide unless I missed it any recomendations or guidelines for base_pagesize values for oracle 10 or 11g. Still looking for those recomendations, guidelines or real life experiences.

Thanks again

norm

Re: Base_pagesize kernel parameter

rick jones — Fri, 12 Feb 2010 00:43:49 GMT

The benefit of using a larger base_pagesize is in the reduction in TLB (Translation Lookaside Buffer - mappings from virtual to physical addresses) and related overheads. IIRC HP Caliper (http://www.hp.com/go/caliper , and comes with the compilers) has the ability to examine the Itanium 2 9000 and 9100 series PMU (Performance Monitoring Unit) to extract information about TLB misses and a great many other things. Probably requires a bit of Caliper manual perusal and may not be 100% grokable to some, but having Caliper traces from before and after the change might help show whether there was much effect on the TLB miss rates.

Using base_pagezize rather than just chatr'ing the binaries helps with things like shared libraries that will be loaded by utilies and startup stuff before your Oracle stuff is running. I suppose it also helps shrink the kernel's pagetables and such.

Re: Base_pagesize kernel parameter

WayneHP — Wed, 17 Feb 2010 15:17:31 GMT

Page 5

Some aspects of large base pages are an unqualified performance benefit. Other aspects depend on the behavior of applications. On balance, HP has found that the performance "sweet spot" is a 16 kB base page size. Many application workloads will show a slight performance improvement with 16 kB base pages as compared to the default. Some workloads, particularly those that manipulate a large number of small objects, are better off with 8 kB or 4 kB base pages. It would be unusual for an application workload to benefit from base pages as large as 64 kB, and therefore we do not recommend that configuration.