| From: | Kevin Grittner <kgrittn(at)ymail(dot)com> |
|---|---|
| To: | James Bottomley <James(dot)Bottomley(at)HansenPartnership(dot)com>, Robert Haas <robertmhaas(at)gmail(dot)com> |
| Cc: | Andres Freund <andres(at)2ndquadrant(dot)com>, Josh Berkus <josh(at)agliodbs(dot)com>, Hannu Krosing <hannu(at)2ndquadrant(dot)com>, "lsf-pc(at)lists(dot)linux-foundation(dot)org" <lsf-pc(at)lists(dot)linux-foundation(dot)org>, "pgsql-hackers(at)postgresql(dot)org" <pgsql-hackers(at)postgresql(dot)org>, Dave Chinner <david(at)fromorbit(dot)com>, Joshua Drake <jd(at)commandprompt(dot)com>, Claudio Freire <klaussfreire(at)gmail(dot)com>, Mel Gorman <mgorman(at)suse(dot)de>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Trond Myklebust <trondmy(at)gmail(dot)com>, Magnus Hagander <magnus(at)hagander(dot)net> |
| Subject: | Re: [Lsf-pc] Linux kernel impact on PostgreSQL performance |
| Date: | 2014-01-14 21:38:01 |
| Message-ID: | 1389735481.63225.YahooMailNeo@web122305.mail.ne1.yahoo.com |
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| Lists: | pgsql-hackers |
James Bottomley <James(dot)Bottomley(at)HansenPartnership(dot)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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