Received: from maia.hub.org (maia-3.hub.org [200.46.204.243]) by mail.postgresql.org (Postfix) with ESMTP id 7A3E71337B53 for ; Fri, 26 Nov 2010 20:46:41 -0400 (AST) Received: from mail.postgresql.org ([200.46.204.86]) by maia.hub.org (mx1.hub.org [200.46.204.243]) (amavisd-maia, port 10024) with ESMTP id 83029-03 for ; Sat, 27 Nov 2010 00:46:34 +0000 (UTC) X-Greylist: delayed 00:05:29.966269 by SQLgrey-1.7.6 Received: from mailhub131.itcs.purdue.edu (mailhub131.itcs.purdue.edu [128.210.5.131]) by mail.postgresql.org (Postfix) with ESMTP id C61241337B89 for ; Fri, 26 Nov 2010 20:46:33 -0400 (AST) Received: from hsohailpc (ece-208-1.dhcp.ecn.purdue.edu [128.46.208.205]) (authenticated bits=0) by mailhub131.itcs.purdue.edu (8.14.4/8.14.4/mta-auth.smtp.purdue.edu) with ESMTP id oAR0f2C2008787 (version=TLSv1/SSLv3 cipher=RC4-MD5 bits=128 verify=NOT) for ; Fri, 26 Nov 2010 19:41:03 -0500 Message-ID: <001201cb8dcb$c4d1c370$cdd02e80@hsohailpc> From: "Hamza Bin Sohail" To: Subject: large page query Date: Fri, 26 Nov 2010 19:41:02 -0500 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_000F_01CB8DA1.DBB42B20" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2900.3664 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.3664 X-PMX-Version: 5.5.9.388399 X-PerlMx-Virus-Scanned: Yes X-Virus-Scanned: Maia Mailguard 1.0.1 X-Spam-Status: No, hits=-2.609 tagged_above=-10 required=5 tests=BAYES_00=-1.9, HTML_MESSAGE=0.001, RCVD_IN_DNSWL_LOW=-0.7, T_RP_MATCHES_RCVD=-0.01 X-Spam-Level: X-Archive-Number: 201011/231 X-Sequence-Number: 36197 This is a multi-part message in MIME format. ------=_NextPart_000_000F_01CB8DA1.DBB42B20 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Hi, I am looking into the impact of large page sizes on the performance of = commercial workloads e.g databases,webserver,virtual machines etc. I was = wondering if I could get to know whether Postgres administrators = configure the Postgres DBMS with large page support for shared memory = regions, specifically on the Solaris 9 and 10 OSes. My understanding is = that since large pages (4 MB) are suitable for applications allocating = large shared memory regions (databases for instance), Postgres would = most definitely use the large page support.=20 So in a nutshell, the questions are=20 1) Does Postgres use large page support ? On solaris 10 and the = ultrasparc III processor, a large page is 4 MB. It significantly reduces = the page table size of the application and a 1000 entry TLB can cover = the entire memory 4G. 2) On Solaris 9 and 10, does Postgres rely on the MPSS support and = relegate the job of figuring out what to allocate as a large page and = what not to, when to allocate a large page and when not to etc ? Or is = it the case that the Postgres developers have written it judiciously and = Postgres itself knows what to and what not to allocate as a large page ? = The reason i ask this question is because, i know for a JVM, solaris 10 = allocates large pages for the heap memory (this is default behavior, no = runtime parameters needed when one runs the JVM. The OS is smart enough = to figure this out) 3) In light of all this, do we know the performance difference between = Postgres configured with no large pages vs Postgres configured with = large pages. Your replies are highly appreciated. Hamza ------=_NextPart_000_000F_01CB8DA1.DBB42B20 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable

Hi,

I am looking into the impact of large = page sizes on=20 the performance of commercial workloads e.g databases,webserver,virtual = machines=20 etc. I was wondering if I could get to know whether Postgres = administrators=20 configure the Postgres DBMS with large page support for shared memory = regions,=20 specifically on the Solaris 9 and 10 OSes. My understanding is that = since large=20 pages (4 MB) are suitable for applications allocating large shared = memory=20 regions (databases for instance), Postgres would most definitely use the = large=20 page support.

So in a nutshell, the = questions are=20

1) Does Postgres use large page support = ? On=20 solaris 10 and the ultrasparc III processor, a large page is 4 MB. It=20 significantly reduces the page table size of the application and a = 1000=20 entry TLB can cover the entire memory 4G.

2) On Solaris 9 and 10, does Postgres = rely on the=20 MPSS support and relegate the job of figuring out what to allocate as a = large=20 page and what not to, when to allocate a large page and when not to etc = ? Or is=20 it the case that the Postgres developers have written it judiciously and = Postgres itself knows what to and what not to allocate as a large page ? = The=20 reason i ask this question is because, i know for a JVM, solaris 10 = allocates=20 large pages for the heap memory (this is default behavior, no runtime = parameters=20 needed when one runs the JVM. The OS is smart enough to figure this=20 out)

3) In light of all this, do we know the = performance=20 difference between Postgres configured with no large pages vs Postgres=20 configured with large pages.

Your replies are highly = appreciated.

Hamza

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