From: Shaun Thomas <sthomas@optionshouse.com>
To: Strahinja Kustudić <strahinjak@nordeus.com>
Cc: pgsql-performance@postgresql.org
Subject: Re: shared_buffers/effective_cache_size on 96GB server
Date: Wed, 10 Oct 2012 09:54:19 -0500
Message-ID: <50758C1B.7010805@optionshouse.com> (raw)
In-Reply-To: <CADKbJJW-q+swRfYPmuy1wKeUh_w9=OcuyOhNSkSeSSeowpPLfw@mail.gmail.com>
References: <CADKbJJUTr9ZWkbajR-7_6qaAsWH0=09=2AMo67C_Az-raKZE4w@mail.gmail.com>
<507573A4.1090605@optionshouse.com>
<CADKbJJXNBLqDFwj3gnaZXdqU1sRU1qRLz=jJnyEWhUQJCC5vNQ@mail.gmail.com>
<50758857.6030008@optionshouse.com>
<CADKbJJW-q+swRfYPmuy1wKeUh_w9=OcuyOhNSkSeSSeowpPLfw@mail.gmail.com>
On 10/10/2012 09:49 AM, Strahinja Kustudić wrote:
> I will change those, but I don't think this is that big of an issue if
> most of the IO is done by Postgres, since Postgres has it's own
> mechanism to tell the OS to sync the data to disk. For example when it's
> writing a wal file, or when it's writing a check point, those do not get
> cached.
You'd be surprised. Greg Smith did a bunch of work a couple years back
that supported these changes. Most DBAs with heavily utilized systems
could even see this in action by turning on checkpoint logging, and
there's an occasional period where the sync time lags into the minutes
due to a synchronous IO switch.
--
Shaun Thomas
OptionsHouse | 141 W. Jackson Blvd. | Suite 500 | Chicago IL, 60604
312-444-8534
sthomas@optionshouse.com
______________________________________________
See http://www.peak6.com/email_disclaimer/ for terms and conditions related to this email
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: pgsql-performance@postgresql.org
Cc: sthomas@optionshouse.com, strahinjak@nordeus.com
Subject: Re: shared_buffers/effective_cache_size on 96GB server
In-Reply-To: <50758C1B.7010805@optionshouse.com>
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
This inbox is served by DDX for PostgreSQL; see mirroring instructions
for how to clone and mirror all data and code used for this inbox