work_mem = 131072 # min 64, size in KB
shared_buffers = 16000 # min 16, at least max_connections*2, 8KB each
checkpoint_segments = 128 # in logfile segments, min 1, 16MB each
effective_cache_size = 750000 # typically 8KB each
fsync=false # turns forced synchronization on or off
------------------------------------------
On Bizgres (0_7_2) running on a 2GHz Opteron:
------------------------------------------
[llonergan@stinger4 bayesBenchmark]$ ./test.sh
real 0m38.348s
user 0m1.422s
sys 0m1.870s
------------------------------------------
On a 2.4GHz AMD64:
------------------------------------------
[llonergan@kite15 bayesBenchmark]$ ./test.sh
real 0m35.497s
user 0m2.250s
sys 0m0.470s
Now we turn fsync=true:
------------------------------------------
On a 2.4GHz AMD64:
------------------------------------------
[llonergan@kite15 bayesBenchmark]$ ./test.sh
real 2m7.368s
user 0m2.560s
sys 0m0.750s
I guess we see the real culprit here. Anyone surprised it's the WAL?
- Luke
________________________________
From: pgsql-performance-owner@postgresql.org on behalf of Andrew McMillan
Sent: Thu 7/28/2005 10:50 PM
To: Matthew Schumacher
Cc: pgsql-performance@postgresql.org
Subject: Re: [PERFORM] Performance problems testing with Spamassassin 3.1.0
On Thu, 2005-07-28 at 16:13 -0800, Matthew Schumacher wrote:
>
> Ok, I finally got some test data together so that others can test
> without installing SA.
>
> The schema and test dataset is over at
> http://www.aptalaska.net/~matt.s/bayes/bayesBenchmark.tar.gz
>
> I have a pretty fast machine with a tuned postgres and it takes it about
> 2 minutes 30 seconds to load the test data. Since the test data is the
> bayes information on 616 spam messages than comes out to be about 250ms
> per message. While that is doable, it does add quite a bit of overhead
> to the email system.
On my laptop this takes:
real 1m33.758s
user 0m4.285s
sys 0m1.181s
One interesting effect is the data in bayes_vars has a huge number of
updates and needs vacuum _frequently_. After the run a vacuum full
compacts it down from 461 pages to 1 page.
Regards,
Andrew.
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