Re: CLOG contention - Mailing list pgsql-hackers

From Robert Haas
Subject Re: CLOG contention
Date
Msg-id CA+TgmoagzcQR69nSRDHygSggfJiKLWFhunw=uToZga5bWw5SiA@mail.gmail.com
Whole thread Raw
In response to Re: CLOG contention  ("Kevin Grittner" <Kevin.Grittner@wicourts.gov>)
Responses Re: CLOG contention  (Merlin Moncure <mmoncure@gmail.com>)
List pgsql-hackers
On Thu, Jan 5, 2012 at 2:44 PM, Kevin Grittner
<Kevin.Grittner@wicourts.gov> wrote:
> If we go with such a formula, I think 32 MB would be a more
> appropriate divisor than 128 MB.  Even on very large machines where
> 32 CLOG buffers would be a clear win, we often can't go above 1 or 2
> GB of shared_buffers without hitting latency spikes due to overrun
> of the RAID controller cache.  (Now, that may change if we get DW
> in, but that's not there yet.)  1 GB / 32 is 32 MB.  This would
> leave CLOG pinned at the minimum of 8 buffers (64 KB) all the way up
> to shared_buffers of 256 MB.

That seems reasonable to me.

--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company


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