From: Przemek Wozniak <wozniak@lanl.gov>
To: Scott Marlowe <scott.marlowe@gmail.com>
Cc: pgsql-performance@postgresql.org
Subject: Re: concurrent IO in postgres?
Date: Thu, 23 Dec 2010 12:46:57 -0700
Message-ID: <1293133617.3685.97.camel@procyon.lanl.gov> (raw)
In-Reply-To: <AANLkTim_m4m-AJsPs0ZvC5zuiXgJpBYmkbJEabYtj2yg@mail.gmail.com>
References: <1293125873.3685.91.camel@procyon.lanl.gov>
<AANLkTim_m4m-AJsPs0ZvC5zuiXgJpBYmkbJEabYtj2yg@mail.gmail.com>
On Thu, 2010-12-23 at 11:24 -0700, Scott Marlowe wrote:
> On Thu, Dec 23, 2010 at 10:37 AM, Przemek Wozniak <wozniak@lanl.gov> wrote:
> > When testing the IO performance of ioSAN storage device from FusionIO
> > (650GB MLC version) one of the things I tried is a set of IO intensive
> > operations in Postgres: bulk data loads, updates, and queries calling
> > for random IO. So far I cannot make Postgres take advantage of this
>
> So, were you running a lot of these at once? Or just single threaded?
> I get very good io concurrency with lots of parallel postgresql
> connections on a 34 disk SAS setup with a battery backed controller.
In one test I was running between 1 and 32 clients simultaneously
writing lots of data using copy binary. The problem is that with a large
RAM buffer it all goes there, and then the background writer, a single
postgres process, will issue write requests one at a time I suspect.
So the actual IO is effectively serialized by the backend.
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To: pgsql-performance@postgresql.org
Cc: wozniak@lanl.gov, scott.marlowe@gmail.com
Subject: Re: concurrent IO in postgres?
In-Reply-To: <1293133617.3685.97.camel@procyon.lanl.gov>
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