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Re: making use of large TLB pages

From: Neil Conway <neilc(at)samurai(dot)com>
To: Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us>
Cc: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>,PostgreSQL Hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: making use of large TLB pages
Date: 2002-09-29 06:04:40
Message-ID: 87bs6hwcuf.fsf@mailbox.samurai.com (view raw or flat)
Thread:
Lists: pgsql-hackers
Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us> writes:
> 	Is TLB Linux-only?

Well, the "TLB" is a feature of the CPU, so no. Many modern processors
support large TLB pages in some fashion.

However, the specific API for using large TLB pages differs between
operating systems. The API I'm planning to implement is the one
provided by recent versions of Linux (2.5.38+).

I've only looked briefly at enabling the usage of large pages on other
operating systems. On Solaris, we already use large pages (due to
using Intimate Shared Memory). On HPUX, you apparently need call
chattr on the executable for it to use large pages. AFAIK the BSDs
don't support large pages for user-land apps -- if I'm incorrect, let
me know.

> 	Why use it and non SysV memory?

It's faster, at least in theory. I posted these links at the start of
the thread:

        http://lwn.net/Articles/6535/
        http://lwn.net/Articles/10293/

> 	Is it a lot of code?

I haven't implemented it yet, so I'm not sure. However, I don't think
it will be a lot of code.

Cheers,

Neil

-- 
Neil Conway <neilc(at)samurai(dot)com> || PGP Key ID: DB3C29FC


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