On Tue, Sep 20, 2011 at 11:01 AM, Marti Raudsepp <marti@juffo.org> wrote:
> On Fri, Sep 16, 2011 at 01:53, Simon Riggs <simon@2ndquadrant.com> wrote:
>> This patch splits bgwriter into 2 processes: checkpointer and
>> bgwriter, seeking to avoid contentious changes. Additional changes are
>> expected in this release to build upon these changes for both new
>> processes, though this patch stands on its own as both a performance
>> vehicle and in some ways a refcatoring to simplify the code.
>
> While you're already splitting up bgwriter, could there be any benefit
> to spawning a separate bgwriter process for each tablespace?
>
> If your database has one tablespace on a fast I/O system and another
> on a slow one, the slow tablespace would also bog down background
> writing for the fast tablespace. But I don't know whether that's
> really a problem or not.
I doubt it. Most of the time the writes are going to be absorbed by
the OS write cache anyway.
I think there's probably more performance to be squeezed out of the
background writer, but maybe not that exact thing, and in any case it
seems like material for a separate patch.
--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company
