Horton

Re: 9.2beta1, parallel queries, ReleasePredicateLocks, CheckForSerializableConflictIn in the oprofile

Sergey Koposov <koposov@ast.cam.ac.uk>

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From: Sergey Koposov <koposov@ast.cam.ac.uk>
To: Ants Aasma <ants@cybertec.at>
Cc: Merlin Moncure <mmoncure@gmail.com>, Robert Haas <robertmhaas@gmail.com>, Florian Pflug <fgp@phlo.org>, Jeff Janes <jeff.janes@gmail.com>, pgsql-hackers@postgresql.org, Stephen Frost <sfrost@snowman.net>
Date: 2012-06-06T11:27:11Z
Lists: pgsql-hackers

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  1. Improve bulk-insert performance by keeping the current target buffer pinned

Hi,

On Mon, 4 Jun 2012, Ants Aasma wrote:
> On Mon, Jun 4, 2012 at 7:44 PM, Merlin Moncure <mmoncure@gmail.com> wrote:
> I tried to keep it simple at first to find an answer to the question
> if it's even worth trying before expending large effort on it. If
> anyone with a multisocket machine would chip in, I'd love to know how
> this patch handles on larger machines. I think the most interesting
> workloads are read only loads with heavy buffer trashing but inside OS
> memory. Select only pgbench with 32MB shared_buffers was withín error
> margin, although slightly faster on my machine (Intel i2500K). The
> workload that I used to demonstrate gain was an aggregated index scan
> to minimise other overheads.

I've quickly tested your lockfree-getbuffer.patch patch with 
the test case you provided and I barely see any improvement (2% at max)
https://docs.google.com/open?id=0B7koR68V2nM1QVBxWGpZdW4wd0U
tested with 24 core (48 ht cores, Xeon E7- 4807).
Although the tps vs number of threads looks weird....

Cheers,
 	S

*****************************************************
Sergey E. Koposov, PhD, Research Associate
Institute of Astronomy, University of Cambridge
Madingley road, CB3 0HA, Cambridge, UK
Tel: +44-1223-337-551 Web: http://www.ast.cam.ac.uk/~koposov/