From: Luke Lonergan <llonergan@greenplum.com>
To: Jeffrey W. Baker <jwbaker@acm.org>
Cc: pgsql-performance@postgresql.org
Subject: Re: Huge Data sets, simple queries
Date: Tue, 31 Jan 2006 21:53:06 -0800
Message-ID: <C0058CC2.1B6B1%llonergan@greenplum.com> (raw)
In-Reply-To: <1138766980.14051.24.camel@noodles>
Jeffrey,
On 1/31/06 8:09 PM, "Jeffrey W. Baker" <jwbaker@acm.org> wrote:
>> ... Prove it.
> I think I've proved my point. Software RAID1 read balancing provides
> 0%, 300%, 100%, and 100% speedup on 1, 2, 4, and 8 threads,
> respectively. In the presence of random I/O, the results are even
> better.
> Anyone who thinks they have a single-threaded workload has not yet
> encountered the autovacuum daemon.
Good data - interesting case. I presume from your results that you had to
make the I/Os non-overlapping (the "skip" option to dd) in order to get the
concurrent access to work. Why the particular choice of offset - 3.2GB in
this case?
So - the bandwidth doubles in specific circumstances under concurrent
workloads - not relevant to "Huge Data sets, simple queries", but possibly
helpful for certain kinds of OLTP applications.
- Luke
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To: pgsql-performance@postgresql.org
Cc: llonergan@greenplum.com, jwbaker@acm.org
Subject: Re: Huge Data sets, simple queries
In-Reply-To: <C0058CC2.1B6B1%llonergan@greenplum.com>
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