Skip site navigation (1) Skip section navigation (2)

Re: testing HS/SR - 1 vs 2 performance

From: Marko Kreen <markokr(at)gmail(dot)com>
To: Simon Riggs <simon(at)2ndquadrant(dot)com>
Cc: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Heikki Linnakangas <heikki(dot)linnakangas(at)enterprisedb(dot)com>, Erik Rijkers <er(at)xs4all(dot)nl>, pgsql-hackers(at)postgresql(dot)org
Subject: Re: testing HS/SR - 1 vs 2 performance
Date: 2010-04-23 17:16:09
Message-ID: s2je51f66da1004231016pc823d9b6yc18a76b32bb3c70e@mail.gmail.com (view raw or flat)
Thread:
Lists: pgsql-hackers
On 4/18/10, Simon Riggs <simon(at)2ndquadrant(dot)com> wrote:
> On Sat, 2010-04-17 at 16:48 -0400, Tom Lane wrote:
>  > There are some places where we suppose that a *single* write into shared
>  > memory can safely be done without a lock, if we're not too concerned
>  > about how soon other transactions will see the effects.  But what you
>  > are proposing here requires more than one related write.
>  >
>  > I've been burnt by this myself:
>  > http://archives.postgresql.org/pgsql-committers/2008-06/msg00228.php
>
>
> W O W - thank you for sharing.
>
>  What I'm not clear on is why you've used a spinlock everywhere when only
>  weak-memory thang CPUs are a problem. Why not have a weak-memory-protect
>  macro that does does nada when the hardware already protects us? (i.e. a
>  spinlock only for the hardware that needs it).

Um, you have been burned by exactly this on x86 also:

  http://archives.postgresql.org/pgsql-hackers/2009-03/msg01265.php

-- 
marko

In response to

Responses

pgsql-hackers by date

Next:From: Tom LaneDate: 2010-04-23 17:38:48
Subject: Re: testing HS/SR - 1 vs 2 performance
Previous:From: Simon RiggsDate: 2010-04-23 16:24:04
Subject: Re: recovery_connections cannot start (was Re: master in standby mode croaks)

Privacy Policy | About PostgreSQL
Copyright © 1996-2014 The PostgreSQL Global Development Group