Re: [Lsf-pc] Linux kernel impact on PostgreSQL performance - Mailing list pgsql-hackers

From Kevin Grittner
Subject Re: [Lsf-pc] Linux kernel impact on PostgreSQL performance
Date
Msg-id 1389735481.63225.YahooMailNeo@web122305.mail.ne1.yahoo.com
Whole thread Raw
In response to Re: Linux kernel impact on PostgreSQL performance  (Josh Berkus <josh@agliodbs.com>)
Responses Re: [Lsf-pc] Linux kernel impact on PostgreSQL performance  (Kevin Grittner <kgrittn@ymail.com>)
List pgsql-hackers
James Bottomley <James.Bottomley@HansenPartnership.com> wrote:

> About how many files comprise this cache?  Are you thinking it's
> too difficult for every process to map the files?

The shared_buffers area can be mapping anywhere from about 200
files to millions of files, representing a total space of about 6MB
on the low end to over 100TB on the high end.  For many workloads
performance falls off above a shared_buffers size of about 8GB,
although for data warehousing environments larger sizes sometimes
work out and to avoid write gluts it must often be limited to 1GB
to 1GB.

Data access is in fixed-sized pages, normally of 8KB each.

--
Kevin Grittner
EDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company



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