From: | Merlin Moncure <mmoncure(at)gmail(dot)com> |
---|---|
To: | Stefan Kaltenbrunner <stefan(at)kaltenbrunner(dot)cc> |
Cc: | PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org> |
Subject: | Re: concurrent COPY performance |
Date: | 2009-06-16 21:33:12 |
Message-ID: | b42b73150906161433n5ce5d4f3r5bc9253bf8c545e2@mail.gmail.com |
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Lists: | pgsql-hackers |
On Tue, Jun 16, 2009 at 12:47 PM, Stefan
Kaltenbrunner<stefan(at)kaltenbrunner(dot)cc> wrote:
> Hi!
>
> I have been doing some bulk loading testing recently - mostly with a focus
> on answering why we are "only" getting a (max of) cores/2(up to around 8
> cores even less with more) speedup using parallel restore.
> What I found is that on some fast IO-subsystem we are CPU bottlenecked on
> concurrent copy which is able to utilize WAL bypass (and scale up to around
> cores/2) and performance without wal bypass is very bad.
> In the WAL logged case we are only able to get a 50% speedup using the
> second process already and we are never able to scale better than 3x (up to
> 8 cores) and performance degrades even after that point.
how are you bypassing wal? do I read this properly that on your 8
core system you are getting 4x speedup with wal bypass and 3x speedup
without?
merlin
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