| From: | Simon Riggs <simon(at)2ndQuadrant(dot)com> |
|---|---|
| To: | Robert Haas <robertmhaas(at)gmail(dot)com> |
| Cc: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, pgsql-hackers(at)postgresql(dot)org |
| Subject: | Re: CLOG contention |
| Date: | 2012-01-05 16:10:21 |
| Message-ID: | CA+U5nM+qzVqsh3ODqzp36yWfRA8niavATpBHzMGbAsT_5X4N_Q@mail.gmail.com |
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| Lists: | pgsql-hackers |
On Thu, Jan 5, 2012 at 4:04 PM, Robert Haas <robertmhaas(at)gmail(dot)com> wrote:
> It appears to me that increasing the number of CLOG buffers reduced
> the severity of the latency spikes considerably. In the last 100
> seconds, for example, master has several spikes in the 500-700ms
> range, but with 32 CLOG buffers it never goes above 400 ms. Also, the
> number of points associated with each spike is considerably less -
> each spike seems to affect fewer transactions. So it seems that at
> least on this machine, increasing the number of CLOG buffers both
> improves performance and reduces latency.
I believed before that the increase was worthwhile and now even more so.
Let's commit the change to 32.
--
Simon Riggs http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Training & Services
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