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Informix Memory Large Pages Sizes

Posted in 2015

Topics: Storage & Space Management, Platform-Specific Issues

Informix DBA — — source: IIUG Forums & Mailing Lists

Hi, We are running Informix 11.70.FC7 on Solaris 11. It seems like all Informix shared memory is using 4 MB page sizes. Solaris supports up to 2 GB page sizes. How to I configure Informix to use larger page sizes when allocating memory. This is different from the BUFFERPOOL page size which is configured according to the page size of the DBSPACE. Thank You, --Dave --f46d041826e6b62bfa0513b3929a

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Marcus Haarmann — — source: IIUG Forums & Mailing Lists

Hi, in our setup (Linux), Informix uses large pages automatically if they are available (these are pre-allocated by entering an entry in /etc/sysctl.conf and activating the setting using sysctl -p). Dunno for Solaris, but Linux shows the pages in /proc/memstat (allocated and available.). Marcus Haarmann ----- Ursprüngliche Mail ----- Von: "Informix DBA" <in4mixdba@gmail.com> An: ids@iiug.org Gesendet: Dienstag, 14. April 2015 20:41:08 Betreff: Informix Memory Large Pages Sizes [34973] Hi, We are running Informix 11.70.FC7 on Solaris 11. It seems like all Informix shared memory is using 4 MB page sizes. Solaris supports up to 2 GB page sizes. How to I configure Informix to use larger page sizes when allocating memory. This is different from the BUFFERPOOL page size which is configured according to the page size of the DBSPACE. Thank You, --Dave --f46d041826e6b62bfa0513b3929a ******************************************************************************* Forum Note: Use "Reply" to post a response in the discussion forum.

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Stefan Sammut — — source: IIUG Forums & Mailing Lists

Your referring to huge pages ? Fully supported and easy to config https://informixdba.wordpress.com/2013/03/08/huge-pages/ Sent from my iPhone > On 14 Apr 2015, at 20:41, Informix DBA <in4mixdba@gmail.com> wrote: > > Hi, > > We are running Informix 11.70.FC7 on Solaris 11. It seems like all > Informix shared memory is using 4 MB page sizes. Solaris supports up to 2 > GB page sizes. How to I configure Informix to use larger page sizes when > allocating memory. This is different from the BUFFERPOOL page size which > is configured according to the page size of the DBSPACE. > > Thank You, > > --Dave > > --f46d041826e6b62bfa0513b3929a > > > ******************************************************************************* > Forum Note: Use "Reply" to post a response in the discussion forum. > Stefan Sammut Manager - Solutions & Innovation [PTL Ltd] Nineteen Twenty Three, Valletta Road Marsa, MRS 3000, MT T +35621445566 +356 99405444 stefan.sammut@ptl.com.mt | www.ptl.com.mt<http://www.ptl.com.mt>; [Facebook]<https://www.facebook.com/PTLMalta/app_349313058487732>; [LinkedIn] <https://www.linkedin.com/company/ptl-ltd?trk=tyah&trkInfo=tarId%3A1401716999276 %2Ctas%3APTL%2Cidx%3A2-3-8> [Twitter] <https://twitter.com/PTL_Malta>; [Youtube] <https://www.youtube.com/channel/UCuXrJBO_54kd9HttG8S89iQ/feed?view_as =public> [Google Plus] <https://plus.google.com/+PTLMalta>;

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RICHARD KOFLER — — source: IIUG Forums & Mailing Lists

Hi Dave, since Solaris 10, 08/11 there is support for MPSS (multiple pg size support) I would check the machine notes of your system, which size is selected by your INFORMIX version OS Command pagesize -a will show you, what is used. It depends on the hardware, if SOLARIS will use 2GB or even 256MB pages or not. See: https://blogs.oracle.com/mandalika/entry/enabling_2_gb_large_pages Apart from (heavily) reducing the TLB misses, there are drawbacks: Large pages are pinned to memory, so it is no longer usable by other processes on the system, which in turn might lead to heavy paging activity on the machine, if INFORMIX's memory consumption is not well tuned in respect of total memory and load of non-INFORMIX activity on the box. On machines having less than 512 GB memory it is risky to use 2GB pagesize, because for every process group using large pages, it also constitutes a minimum of allocation. HTH dic_k

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david@smooth1.co.uk — — source: IIUG Forums & Mailing Lists

You may need to use what used to be Intimate Shared Memory which used to be pinned in memory (used a seperate kernel driver). Try setting REDIDENT to 1,2,3 or if brave -1 and see if Informix will then automatically used large pages. Regards, David, > On 15 April 2015 at 09:29 RICHARD KOFLER <richard.kofler@chello.at> wrote: > > > Hi Dave, > > since Solaris 10, 08/11 there is support for MPSS (multiple pg size support) > > I would check the machine notes of your system, which size is selected by > your INFORMIX version > > OS Command pagesize -a will show you, what is used. > > It depends on the hardware, if SOLARIS will use 2GB or even 256MB pages or > not. > > See: > https://blogs.oracle.com/mandalika/entry/enabling_2_gb_large_pages > > Apart from (heavily) reducing the TLB misses, there are drawbacks: Large pages > are pinned to memory, so it is no longer usable by other processes on the > system, which in turn might lead to heavy paging activity on the machine, if > INFORMIX's memory consumption is not well tuned in respect of total memory and > load of non-INFORMIX activity on the box. On machines having less than 512 GB > memory it is risky to use 2GB pagesize, because for every process group using > large pages, it also constitutes a minimum of allocation. > > HTH > dic_k > > > ******************************************************************************* > Forum Note: Use "Reply" to post a response in the discussion forum. >

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