Re: [GENERAL] Up to date conventional wisdom re max shared_buffersize? - Mailing list pgsql-general

From Andres Freund
Subject Re: [GENERAL] Up to date conventional wisdom re max shared_buffersize?
Date
Msg-id 20170919235011.vhceiey37d3kl4ic@alap3.anarazel.de
Whole thread Raw
In response to [GENERAL] Up to date conventional wisdom re max shared_buffer size?  (Jerry Sievers <gsievers19@comcast.net>)
Responses Re: [GENERAL] Up to date conventional wisdom re max shared_buffer size?  (Jerry Sievers <gsievers19@comcast.net>)
List pgsql-general
Hi,

On 2017-09-19 17:00:05 -0500, Jerry Sievers wrote:
> Briefly, just curious if legacy max values for shared_buffers have
> scaled up since 8G was like 25% of RAM?

It's very workload dependent. I've successfully used PG with roughly 1TB
of shared buffers, where that performed better than lower
settings.


> Pg 9.3 on monster 2T/192 CPU Xenial thrashing

Not sure what the word "thrashing" in that sentence means.

Things have improved a lot since 9.3 WRT to scalability, so I'd not
infer too much from 9.3 performance on a larger box.


> Upgrade pending but we recently started having $interesting performance
> issues at times looking like I/O slowness and other times apparently
> causing CPU spins.

That's not something we can really usefully comment on given the amount
of information.

> Anyway, shared_buffer coherency generally high but does take big dips
> that are sometimes sustained for seconds or even minutes.

"shared_buffer coherency"?


Greetings,

Andres Freund


-- 
Sent via pgsql-general mailing list (pgsql-general@postgresql.org)
To make changes to your subscription:
http://www.postgresql.org/mailpref/pgsql-general

pgsql-general by date:

Previous
From: John R Pierce
Date:
Subject: Re: [GENERAL] [HACKERS] USER Profiles for PostgreSQL
Next
From: Peter Koukoulis
Date:
Subject: [GENERAL] random row from a subset