Horton

Re: Clock sweep not caching enough B-Tree leaf pages?

Bruce Momjian <bruce@momjian.us>

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From: Bruce Momjian <bruce@momjian.us>
To: Atri Sharma <atri.jiit@gmail.com>
Cc: Peter Geoghegan <pg@heroku.com>, Greg Stark <stark@mit.edu>, Ants Aasma <ants@cybertec.at>, Pg Hackers <pgsql-hackers@postgresql.org>
Date: 2014-04-18T22:07:36Z
Lists: pgsql-hackers 
On Sat, Apr 19, 2014 at 01:21:29AM +0530, Atri Sharma wrote:
> I feel that if there is no memory pressure, frankly it doesnt matter much about
> what gets out and what not. The case I am specifically targeting is when the
> clocksweep gets to move about a lot i.e. high memory pressure workloads. Of
> course,  I may be totally wrong here.
> 
> One thing that I discussed with Merlin offline and am now concerned about is
> how will the actual eviction work. We cannot traverse the entire list and then
> find all the buffers with refcount 0 and then do another traversal to find the
> oldest one.

I thought if there was memory pressure the clock sweep would run and we
wouldn't have everything at the max counter access value.

-- 
  Bruce Momjian  <bruce@momjian.us>        http://momjian.us
  EnterpriseDB                             http://enterprisedb.com

  + Everyone has their own god. +

Commits

  1. Replace the BufMgrLock with separate locks on the lookup hashtable and