Re: measuring spinning

Simon Riggs <simon@2ndquadrant.com>

From: Simon Riggs <simon@2ndQuadrant.com>

To: Robert Haas <robertmhaas@gmail.com>

Cc: pgsql-hackers@postgresql.org

Date: 2012-01-12T09:00:25Z

Lists: pgsql-hackers

On Thu, Jan 12, 2012 at 1:48 AM, Robert Haas <robertmhaas@gmail.com> wrote:

> Just to whet your appetite, here are the top spinners on a 32-client
> SELECT-only test on a 32-core Itanium server.  All the locks not shown
> below have two orders of magnitude less of a problem than these do.

Please can you repeat the test, focusing on minutes 10-30 of a 30
minute test run. That removes much of the noise induced during cache
priming.

My suggested size of database is one that is 80% size of RAM, with
shared_buffers set to 40% of RAM or 2GB whichever is higher. That
represents the common case where people know how big their data is and
purchase RAM accordingly, then set shared_buffers in line with current
wisdom.

-- 
 Simon Riggs                   http://www.2ndQuadrant.com/
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