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Re: [PATCH] Prefetch index pages for B-Tree index scans

From: Bruce Momjian <bruce(at)momjian(dot)us>
To: John Lumby <johnlumby(at)hotmail(dot)com>
Cc: Claudio Freire <klaussfreire(at)gmail(dot)com>, greg(at)2ndquadrant(dot)com,pgsql hackers <pgsql-hackers(at)postgresql(dot)org>, Cédric Villemain <cedric(at)2ndquadrant(dot)com>
Subject: Re: [PATCH] Prefetch index pages for B-Tree index scans
Date: 2012-11-05 20:39:04
Message-ID: (view raw, whole thread or download thread mbox)
Lists: pgsql-hackers
On Fri, Nov  2, 2012 at 09:59:08AM -0400, John Lumby wrote:
> Thanks for the mentioning this posting.    Interesting.
> However,    the OP describes an implementation based on libaio. 
> Today what we have (for linux) is librt,  which is quite different.
> It is arguable worse than libaio (well actually I am sure it is worse)
> since it is essentially just an encapsulation of using threads to do
> synchronous ios  -  you can look at it as making it easier to do what the 
> application could do itself if it set up its own pthreads.     The linux
> kernel does not know about it and so the CPU overhead of checking for
> completion is higher.

Well, good thing we didn't switch to using libaio, now that it is gone.

  Bruce Momjian  <bruce(at)momjian(dot)us>

  + It's impossible for everything to be true. +

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