Re: Performance drop after upgrading to 8.4.4?

On Thu, Jun 3, 2010 at 9:22 AM, Max Williams <Max(dot)Williams(at)mflow(dot)com> wrote:
> Hi,
>
> I was doing some benchmarking while changing configuration options to try to
> get more performance out of our postgresql servers and noticed that when
> running pgbench against 8.4.3 vs 8.4.4 on identical hardware and
> configuration there is a large difference in performance. I know tuning is a
> very deep topic and benchmarking is hardly an accurate indication of real
> world performance but I was still surprised by these results and wanted to
> know what I am doing wrong.
>
>
>
> Hardware specs are:
>
> 2x Quad core Xeons 2.4Ghz
>
> 16GB RAM
>
> 2x RAID1 7.2k RPM disks
>
>
>
> Relevant Postgresql Configuration:
>
> max_connections = 1000
>
> shared_buffers = 4096MB
>
> temp_buffers = 8MB
>
> max_prepared_transactions = 1000
>
> work_mem = 8MB
>
> maintenance_work_mem = 512MB
>
> wal_buffers = 8MB
>
> checkpoint_segments = 192
>
> checkpoint_timeout = 30min
>
> effective_cache_size = 12288MB
>
>
>
> Results for the 8.4.3 (8.4.3-2PGDG.el5) host:
>
> [root(at)some-host ~]# pgbench -h dbs3 -U postgres -i -s 100 pgbench1 >
> /dev/null 2>&1 && pgbench -h dbs3 -U postgres -c 100 -t 100000 pgbench1
>
> starting vacuum...end.
>
> transaction type: TPC-B (sort of)
>
> scaling factor: 100
>
> query mode: simple
>
> number of clients: 100
>
> number of transactions per client: 100000
>
> number of transactions actually processed: 10000000/10000000
>
> tps = 4612.734318 (including connections establishing)
>
> tps = 4613.308264 (excluding connections establishing)
>
>
>
> Results for the 8.4.4 (8.4.4-1PGDG.el5) host:
>
> [root@ some-host ~]# pgbench -h dbs4 -U postgres -i -s 100 pgbench1 >
> /dev/null 2>&1 && pgbench -h dbs4 -U postgres -c 100 -t 100000 pgbench1
>
> starting vacuum...end.
>
> transaction type: TPC-B (sort of)
>
> scaling factor: 100
>
> query mode: simple
>
> number of clients: 100
>
> number of transactions per client: 100000
>
> number of transactions actually processed: 10000000/10000000
>
> tps = 2799.134267 (including connections establishing)
>
> tps = 2799.451407 (excluding connections establishing)
>
>
>
> Any input? I can reproduce these numbers consistently. By the way, I am a
> new postgresql user so my experience is limited.

nothing jumps out to me in terms of the release notes. any chance of
getting some oprofile runs?

merlin