Re: SHM_HUGETLB on Linux 2.6.

Kurt Roeckx wrote:
> Hi,
>
> Has anyone tried to use the huge tlb support of the Linux 2.6 kernel?
> If you compile the kernel with support for it (CONFIG_HUGETLBFS), you
> can call shmget() with a SHM_HUGETLB parameter so that it will use
> larger pages.
>
> Has anyone tried to use it? Is it worth trying to set it up?

I tried to apply HugeTlb on shared memory segment, but it does not
provide us statistically-meaningful difference on PostgreSQL.

pgbench gave us the following result, with shared_buffer_size=160mb
and Core2Duo E6400, total system memory=512MB.
Unfortunatelly, any other detailed parameters were lost.

Transaction per sec Average STD
-----------------------------------------------
pgsql-8.2.5 (normal) : 656.6118 17.5006
pgsql-8.2.5 (hugetlb) : 655.3389 20.2623

A similar topic was also posted at Mar 2007.
http://archives.postgresql.org/pgsql-hackers/2007-03/msg00232.php

Regard,
--
OSS Platform Development Division, NEC
KaiGai Kohei <kaigai(at)ak(dot)jp(dot)nec(dot)com>