From: Kevin Grittner <Kevin.Grittner@wicourts.gov>
To: Robert Haas <robertmhaas@gmail.com>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Greg Smith <gsmith@gregsmith.com>
Cc: pgsql-performance@postgresql.org <pgsql-performance@postgresql.org>
Cc: Scott Carey <scott@richrelevance.com>
Cc: Jignesh K. Shah <J.K.Shah@sun.com>
Subject: Re: Proposal of tunable fix for scalability of 8.4
Date: Fri, 13 Mar 2009 13:02:24 -0500
Message-ID: <49BA5960.EE98.0025.0@wicourts.gov> (raw)
In-Reply-To: <12292.1236964604@sss.pgh.pa.us>
References: <alpine.GSO.2.01.0903121613270.1925@westnet.com>
<C5DED7A7.33B2%scott@richrelevance.com>
<603c8f070903121829r31cf1472ha9876e5c480a542e@mail.gmail.com>
<603c8f070903121829r31cf1472ha9876e5c480a542e@mail.gmail.com>
<12292.1236964604@sss.pgh.pa.us>
Tom Lane <tgl@sss.pgh.pa.us> wrote:
> Robert Haas <robertmhaas@gmail.com> writes:
>> I think that changing the locking behavior is attacking the problem
>> at the wrong level anyway.
>
> Right. By the time a patch here could have any effect, you've
> already lost the game --- having to deschedule and reschedule a
> process is a large cost compared to the typical lock hold time for
> most LWLocks. So it would be better to look at how to avoid
> blocking in the first place.
That's what motivated my request for a profile of the "80 clients with
zero wait" case. If all data access is in RAM, why can't 80 processes
keep 64 threads (on 8 processors) busy? Does anybody else think
that's an interesting question, or am I off in left field here?
-Kevin
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To: pgsql-performance@postgresql.org
Cc: Kevin.Grittner@wicourts.gov, robertmhaas@gmail.com, tgl@sss.pgh.pa.us, gsmith@gregsmith.com, scott@richrelevance.com, J.K.Shah@sun.com
Subject: Re: Proposal of tunable fix for scalability of 8.4
In-Reply-To: <49BA5960.EE98.0025.0@wicourts.gov>
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