On Thu, 2 May 2013 06:07:13 -0500, Markus Haselbach <markus.haselb...@credit-suisse.com> wrote:
>Hello, > >we start using LFAREA (1M pages) with z/OS 1.13 and DB2 10 on z196. >From IBM I read: "Using large pages can improve performance for some >applications by reducing the overhead of dynamic address translation". >We wonder how to measure this performance improvement. What we're trying now >is measuring and comparing CPU usage/ SQL with and without 1M pages. >Does someone have experience with this performance improvement and can anybody >advice me on what should/could be measured? > >kind regards >Markus > My client implemented LFAREA a few years ago under z/OS 1.10 for WebSphere running in 64-bit mode / using 64-bit Java. I think we waited for the 64-bit Java performance improvement (along with z/OS support - RSM APAR OA26294) when it started using the hole / dead zone between 2G-4G via compressed address pointers. There are two LPARs with about 180G of real storage running WAS and 80G of it is LFAREA. The size is based on the number of WAS regions and their JVM sizea. Because of this "planning" and adequate real storage, no 1M frames get used for 4K pages nor is there any coalescing (this out of "force" because the function didn't even work as documentd until OA31116!). To the best of my recollection (my client has a performance team that focuses on this sort of thing and the ones involved are no longer around to ask), all we measured was the end user response time - which did improve (and this is really all the client cared about). Obviously there is an underlying CPU usage improvement, but I'm not sure where it would show up in (*master*)? Mark -- Mark Zelden - Zelden Consulting Services - z/OS, OS/390 and MVS mailto:m...@mzelden.com Mark's MVS Utilities: http://www.mzelden.com/mvsutil.html Systems Programming expert at http://expertanswercenter.techtarget.com/ ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
