public inbox for [email protected]  

help / color / mirror / Atom feed

From: Andres Freund <[email protected]>
To: Tom Lane <[email protected]>
Cc: Melanie Plageman <[email protected]>
Cc: Greg Stark <[email protected]>
Cc: Kyotaro Horiguchi <[email protected]>
Cc: Justin Pryzby <[email protected]>
Cc: Thomas Munro <[email protected]>
Cc: David G. Johnston <[email protected]>
Cc: PostgreSQL Hackers <[email protected]>
Subject: Re: shared-memory based stats collector - v70
Date: Wed, 20 Jul 2022 09:34:24 -0700
Message-ID: <[email protected]> (raw)
In-Reply-To: <[email protected]>
References: <CAAKRu_YsFzW3jsQUD7MVUY8c+87OiKW_Y93TsPAfLr3zi_jX9w@mail.gmail.com>
	<[email protected]>
	<[email protected]>
	<[email protected]>
	<[email protected]>
	<[email protected]>
	<[email protected]>
	<CAM-w4HN=4ss5dS2DH6Cof=zocJXeGOjRNKxEGgUZdJPMndyNzA@mail.gmail.com>
	<CAAKRu_Z18jYbarKA4GZMOO00KtUqKtBqgQ8SgB=wSvSqKq3iiA@mail.gmail.com>
	<[email protected]>

Hi,

On 2022-07-20 12:08:35 -0400, Tom Lane wrote:
> AFAIR, the previous stats collector implementation had no such provision
> either: it'd just keep adding hashtable entries as it received info about
> new objects.

Yep.


> The only thing that's changed is that now those entries are in shared
> memory instead of process-local memory.  We'd be well advised to be
> sure that memory can be swapped out under pressure, but otherwise I'm
> not seeing that things have gotten worse.

FWIW, I ran a few memory usage benchmarks. Without stats accesses the
memory usage with shared memory stats was sometimes below, sometimes
above the "old" memory usage, depending on the number of objects. As
soon as there's stats access, it's well below (that includes things like
autovac workers).

I think there's quite a bit of memory usage reduction potential around
dsa.c - we occasionally end up with [nearly] unused dsm segments.

Greetings,

Andres Freund

view thread (82+ messages)  latest in thread

reply

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Reply to all the recipients using the --to and --cc options:
  reply via email

  To: [email protected]
  Cc: [email protected], [email protected], [email protected], [email protected], [email protected], [email protected], [email protected], [email protected], [email protected]
  Subject: Re: shared-memory based stats collector - v70
  In-Reply-To: <[email protected]>

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

This inbox is served by agora; see mirroring instructions
for how to clone and mirror all data and code used for this inbox