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Re: large page query

From: Robert Haas <robertmhaas(at)gmail(dot)com>
To: Hamza Bin Sohail <hsohail(at)purdue(dot)edu>
Cc: pgsql-hackers(at)postgresql(dot)org
Subject: Re: large page query
Date: 2010-11-29 17:09:21
Message-ID: AANLkTin5WSJPFetwiW6+=7CtAYLk9+HuS5vqP619X=Xj@mail.gmail.com (view raw or flat)
Thread:
Lists: pgsql-hackers
On Mon, Nov 29, 2010 at 12:05 PM, Hamza Bin Sohail <hsohail(at)purdue(dot)edu> wrote:
> 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 provided by
> the Operating system 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 to the Operating system? 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 by probably looking at
> what is the app that is running )
>
> 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.

To the best of my knowledge, PostgreSQL has no configuration options
to use large page support on any architecture.

-- 
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company

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