pgbench results

[Ivan Voras]

http://www.kaltenbrunner.cc/blog/index.php?/archives/21-guid.html

alan bryan wrote:

> Here's mine for a somewhat similar setup.  
> FreeBSD 7.0 PostgreSQL 8.3
> 2x Intel Xeon 2.33GHZ quad cores (8 cores total), 8GB
> RAM, 250GB RAID 10 (4x WD Raptor 10K drives).
> 
> Non-default settings: 
> 
>                         
> max_connections = 200 
> shared_buffers = 1900MB
> wal_buffers = 1024kB
> checkpoint_segments = 192             
> checkpoint_timeout = 30min 
> 
> createdb testdb
> pgbench -i -s 100 testdb
> 
> # pgbench -c 100 -t 100000 testdb
> starting vacuum...end.
> transaction type: TPC-B (sort of)
> scaling factor: 100
> number of clients: 100
> number of transactions per client: 100000
> number of transactions actually processed:
> 10000000/10000000
> tps = 1650.806584 (including connections establishing)
> tps = 1650.905036 (excluding connections establishing)
> 
> So, not as high as his numbers but then I've got less
> RAM, one less drive spindle in my array (2 vs. 3 in
> performance for the raid 10 setup), SATA vs. SCSI,
> he's got 512MB of controller cache vs my 128MB.

The thing is - I *do* have a similar setup here: HP DL370 G5, 2x4-core
1.86 GHz, 4 GB RAM, 6 drives in RAID10, 512 MB cache (can pull > 200
MB/s off the array), with all settings like in the posted link except
shared_buffer=1900 MB, and I "only" get this:

tps = 2834.026175 (including connections establishing)
tps = 2839.080739 (excluding connections establishing)

This is still far bellow ~~ 4500 trans/s from the link and I wonder if
my results are within what I should be getting. The benchmark in the
link above was done with faster CPUs (but I'm not CPU bound - at least
30% idle), but with 3 times the memory and I'm guessing more memory
would help here, but I'm not sure.

What's strange is that toggling synchronous_commit doesn't have a
significant effect on performance (it does increase CPU idle time). With
synchronous_commit=off, I get:

tps = 2886.980477 (including connections establishing)
tps = 2891.776081 (excluding connections establishing)

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