From: Tom Lane <tgl@sss.pgh.pa.us>
To: Michael Heaney <mheaney@jcvi.org>
cc: "pgsql-admin@postgresql.org" <pgsql-admin@postgresql.org>
Subject: Re: Huge pages not working on PG 9.4
In-reply-to: <54B9C41D.10109@jcvi.org>
References: <54B98BB5.4050902@jcvi.org>
 <73DC9DCF-7C2D-49F7-8E8C-19F9C9E13854@elevated-dev.com>
 <54B991F5.7040505@jcvi.org> <54B995CE.5010301@jcvi.org>
 <28981.1421452694@sss.pgh.pa.us> <54B9C41D.10109@jcvi.org>
Comments: In-reply-to Michael Heaney <mheaney@jcvi.org>
 message dated "Fri, 16 Jan 2015 21:08:29 -0500"
Date: Fri, 16 Jan 2015 22:52:37 -0500
Message-ID: <2824.1421466757@sss.pgh.pa.us>
Precedence: bulk
Sender: pgsql-admin-owner@postgresql.org

Michael Heaney <mheaney@jcvi.org> writes:
> On 1/16/2015 6:58 PM, Tom Lane wrote:
>> A quick look at the PG source code says that that message means that
>> MAP_HUGETLB isn't defined.  Our code is expecting <sys/mman.h> to provide
>> that symbol, which it should do by default according to what I can see on
>> my RHEL 6.6 box.  Perhaps you've defined some of the feature restriction
>> macros like _POSIX_SOURCE?

> Thanks for the helpful clue, Tom.  I haven't knowingly defined 
> _POSIX_SOURCE or any other macros. I go through the same configure/make 
> process on the Centos 6.6 VM on my home PC, and huge pages works just 
> fine.  Maybe it's an issue with CentOS  6.4?

Dunno, hard to believe that hugetlb support wasn't there in 6.4.  A quick
troll through the RHEL 6.5 and 6.6 release notes finds something about
better hugetlb support for System Z processors, but what we're discussing
here shouldn't be architecture-specific.

You might try comparing /usr/include/sys/mman.h, /usr/include/bits/mman.h,
and /usr/include/features.h between your 6.4 and 6.6 systems to see if
you can spot any relevant differences.

			regards, tom lane


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