Re: 20% performance drop on PostgreSQL 9.2 from kernel 3.5.3 to 3.6-rc5 on AMD chipsets

On Fri, Sep 14, 2012 at 12:40 AM, Nikolay Ulyanitsky <lystor(at)gmail(dot)com>wrote:

> Hi
> I compiled the 3.6-rc5 kernel with the same config from 3.5.3 and got
> the 15-20% performance drop of PostgreSQL 9.2 on AMD chipsets (880G,
> 990X).
>

Did you compile the AMD code on the AMD system?

We use a different open-source project that provides chemistry
functionality, and discovered the hard way that the code optimizer is
specific to each chip. Code compiled on Intel chips would sometimes run
50% slower on AMD chips (and vice versa). When we compiled the Intel code
using Intel computers and AMD code using AMD computers, the performance
difference disappeared.

There's probably an optimizer flag somewhere that would allow you to force
it to compile for one chip or the other, but by default it seems to pick
the one you're running on.

Craig

>
> CentOS 6.3 x86_64
> PostgreSQL 9.2
> cpufreq scaling_governor - performance
>
> # /etc/init.d/postgresql initdb
> # echo "fsync = off" >> /var/lib/pgsql/data/postgresql.conf
> # /etc/init.d/postgresql start
> # su - postgres
> $ psql
> # create database pgbench;
> # \q
>
> # pgbench -i pgbench && pgbench -c 10 -t 10000 pgbench
> tps = 4670.635648 (including connections establishing)
> tps = 4673.630345 (excluding connections establishing)[/code]
>
> On kernel 3.5.3:
> tps = ~5800
>
> 1) Host 1 - 15-20% performance drop
> AMD Phenom(tm) II X6 1090T Processor
> MB: AMD 880G
> RAM: 16 Gb DDR3
> SSD: PLEXTOR PX-256M3 256Gb
>
> 2) Host 2 - 15-20% performance drop
> AMD Phenom(tm) II X6 1055T Processor
> MB: AMD 990X
> RAM: 32 Gb DDR3
> SSD: Corsair Performance Pro 128Gb
>
> 3) Host 3 - no problems - same performance
> Intel E6300
> MB: Intel® P43 / ICH10
> RAM: 4 Gb DDR3
> HDD: SATA 7200 rpm
>
> Kernel config - http://pastebin.com/cFpg5JSJ
>
> Any ideas?
>
> Thx
>
>
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