Simon,
I am seeing a reasonably reproducible performance boost after applying
your patch (I'm not sure if that was one of the main objectives, but it
certainly is nice).
I *was* seeing a noticeable decrease between 7.4.6 and 8.0.0RC1 running
pgbench. However, after applying your patch, 8.0 is pretty much back to
being the same.
Now I know pgbench is ..err... not always the most reliable for this
sort of thing, so I am interested if this seems like a reasonable sort
of thing to be noticing (and also if anyone else has noticed the
decrement)?
(The attached brief results are for Linux x86, but I can see a similar
performance decrement 7.4.6->8.0.0RC1 on FreeBSD 5.3 x86)
regards
Mark
Simon Riggs wrote:
>Hmm...must confess that my only plan is:
>i) discover dynamic behaviour of bgwriter
>ii) fix any bugs or wierdness as quickly as possible
>iii) try to find a way to set the bgwriter defaults
>
>
>
System
------
P4 2.8Ghz 1G 1xSeagate Barracuda 40G
Linux 2.6.9 glibc 2.3.3 gcc 3.4.2
Postgresql 7.4.6 | 8.0.0RC1
Test
----
Pgbench with scale factor = 200
Pg 7.4.6
--------
clients transactions tps
1 1000 65.1
2 1000 72.5
4 1000 69.2
8 1000 48.3
Pg 8.0.0RC1
-----------
clients transactions tps tps (new buff patch + settings)
1 1000 55.8 70.9
2 1000 68.3 77.9
4 1000 38.4 62.8
8 1000 29.4 38.1
(averages over 3 runs, database dropped and recreated after each set, with a
checkpoint performed after each individual run)
Parameters
----------
Non default postgresql.conf parameters:
tcpip_socket = true [listen_addresses = "*"]
max_connections = 100
shared_buffers = 10000
wal_buffers = 1024
checkpoint_segments = 10
effective_cache_size = 40000
random_page_cost = 0.8
bgwriter settings (used with patch only)
bgwriter_delay = 200
bgwriter_percent = 2
bgwriter_maxpages = 100
