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From: Simon Riggs <simon@2ndquadrant.com>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Jignesh K. Shah <J.K.Shah@Sun.COM>
Cc: Josh Berkus <josh@agliodbs.com>
Cc: pgsql-performance@postgresql.org
Cc: Alvaro Herrera <alvherre@commandprompt.com>
Subject: Re: User concurrency thresholding: where do I look?
Date: Mon, 23 Jul 2007 18:50:53 +0100
Message-ID: <1185213053.4284.278.camel@ebony.site> (raw)
In-Reply-To: <27521.1185208528@sss.pgh.pa.us>
References: <200707190828.59088.josh@agliodbs.com>
	<200707191819.13899.josh@agliodbs.com>
	<15685.1184895926@sss.pgh.pa.us>
	<200707192138.39679.josh@agliodbs.com>
	<46A0FA31.2080208@sun.com>
	<12002.1184955831@sss.pgh.pa.us>
	<46A1055F.9010304@sun.com>
	<12445.1184958793@sss.pgh.pa.us>
	<46A11116.5030905@sun.com>
	<14909.1184962561@sss.pgh.pa.us>
	<46A1205B.8010205@sun.com>
	<15343.1184965054@sss.pgh.pa.us>
	<1185180668.4284.149.camel@ebony.site>
	<23848.1185199901@sss.pgh.pa.us>
	<1185201556.4284.243.camel@ebony.site>
	<25095.1185202498@sss.pgh.pa.us>
	<1185205663.4284.249.camel@ebony.site>
	<27521.1185208528@sss.pgh.pa.us>

On Mon, 2007-07-23 at 12:35 -0400, Tom Lane wrote:
> "Simon Riggs" <simon@2ndquadrant.com> writes:
> > Well, I discover there is an allocation of 8232 (inflation...) made once
> > per statement by a memory context called... ExecutorState. Still not
> > sure exactly which allocation this is, but its definitely once per
> > statement on pgbench, which should narrow it down. Plan, query etc?
> 
> Are you working with stock sources?  The only allocation exceeding 1K
> that I can see during pgbench is BTScanOpaqueData, which is 6600 bytes.
> (Checked by setting a conditional breakpoint on AllocSetAlloc.)  The
> path that allocates a single-chunk block is never taken at all.

I do have the bitmap patch currently applied, but it doesn't touch that
part of the code.

(gdb) p size
$1 = 8232

(gdb) p sizeof(int)
$2 = 4

(gdb) p sizeof(BTScanPosData)
$3 = 4104

Since my notes say I got 8228 last year, seems reasonable.

-- 
  Simon Riggs
  EnterpriseDB  http://www.enterprisedb.com




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  Subject: Re: User concurrency thresholding: where do I look?
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