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Re: making use of large TLB pages

From: "Jonah H(dot) Harris" <jharris(at)nightstarcorporation(dot)com>
To: "'Neil Conway'" <neilc(at)samurai(dot)com>
Cc: "'Bruce Momjian'" <pgman(at)candle(dot)pha(dot)pa(dot)us>,"'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: 2002-09-30 02:49:12
Message-ID: 001901c2682b$f5b7efb0$b77b2344@gemini (view raw or flat)
Thread:
Lists: pgsql-hackers
Neil,

I agree with Bruce and Tom.  AFAIK and in my experience I don't think it
will be a significantly measurable increase.  Not only that, but the
portability issue itself tends to make it less desireable.  I recently
ported SAP DB and the coinciding DevTools over to OpenBSD and learned again
first-hand what a pain in the ass having platform-specific code is.  I guess
it's up to you, Neil.  If you want to spend the time trying to implement it,
and it does prove to have a significant performance increase I'd say maybe.
IMHO, I just think that time could be better spent improving the current
system rather than trying to add to it in a singular way.  Sorry if my
comments are out-of-line on this one but it has been a thread for some time
I'm just kinda tired of reading theory vs proof.

Since you are so set on trying to implement this, I'm just wondering what
documentation has tested evidence of measurable increases in similar
situations?  I just like arguments to be backed by proof... and I'm sure
there is documentation on this somewhere.

-Jonah

-----Original Message-----
From: pgsql-hackers-owner(at)postgresql(dot)org
[mailto:pgsql-hackers-owner(at)postgresql(dot)org]On Behalf Of Bruce Momjian
Sent: Sunday, September 29, 2002 3:30 PM
To: Tom Lane
Cc: Neil Conway; PostgreSQL Hackers
Subject: Re: [HACKERS] making use of large TLB pages


Tom Lane wrote:
> Neil Conway <neilc(at)samurai(dot)com> writes:
> > Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us> writes:
> >> OK, personally, I would like to see an actual speedup of PostgreSQL
> >> queries before I would apply such a OS-specific, version-specific
> >> patch.
>
> > Don't be silly. A performance improvement is a performance
> > improvement.
>
> No, Bruce was saying that he wanted to see demonstrable improvement
> *due to this specific change* before committing to support a
> platform-specific API.  I agree with him, actually.  If you do the
> TLB code and can't measure any meaningful performance improvement
> when using it vs. when not, I'd not be excited about cluttering the
> distribution with it.
>
> > I think it's at least worth implementing -- if it doesn't provide a
> > noticeable performance improvement, then we don't need to merge it.
>
> You're on the same page, you just don't realize it...

I see what he thought I said, I just can't figure out how he read it
that way.

--
  Bruce Momjian                        |  http://candle.pha.pa.us
  pgman(at)candle(dot)pha(dot)pa(dot)us               |  (610) 359-1001
  +  If your life is a hard drive,     |  13 Roberts Road
  +  Christ can be your backup.        |  Newtown Square, Pennsylvania 19073

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Subject: Re: making use of large TLB pages
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