| From: | Simon Riggs <simon(at)2ndQuadrant(dot)com> |
|---|---|
| To: | Robert Haas <robertmhaas(at)gmail(dot)com> |
| Cc: | pgsql-hackers(at)postgresql(dot)org |
| Subject: | Re: measuring spinning |
| Date: | 2012-01-12 09:00:25 |
| Message-ID: | CA+U5nMK0YHdAKs=FAxW0AViCx5U6znTLmQGStBqcZcBvfgo4bQ@mail.gmail.com |
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| Lists: | pgsql-hackers |
On Thu, Jan 12, 2012 at 1:48 AM, Robert Haas <robertmhaas(at)gmail(dot)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/
PostgreSQL Development, 24x7 Support, Training & Services
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