new group commit behavior not helping?

From: Jeff Janes <jeff(dot)janes(at)gmail(dot)com>
To: Robert Haas <robertmhaas(at)gmail(dot)com>
Cc: "pgsql-hackers(at)postgresql(dot)org" <pgsql-hackers(at)postgresql(dot)org>
Subject: new group commit behavior not helping?
Date: 2012-04-01 05:40:17
Message-ID: CAMkU=1xGw7P2t8c-TCMErbn6R5pNR+q1BVNs-SiFeOcGg2eLSA@mail.gmail.com
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On Saturday, March 31, 2012, Robert Haas <robertmhaas(at)gmail(dot)com> wrote:
> Hoping to demonstrate the wonders of our new group commit code, I ran
> some benchmarks on the IBM POWER7 machine with synchronous_commit =
> on. But, it didn't come out much better than 9.1.

Where I would expect (and have seen) much improvement is where #clients >>
#CPU. Or "cores", whatever the term of art is.

Of course I've mostly seen this where CPU=1

It looks like in your case tps was still scaling with clients when you gave
up, so clients was probably too small.

Jeff

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