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

Regards, Nikolay.
Like Daniel said to you, I encourage to inform all your findings to the LKML to
report all these problems.

Only one las t question: Did you tune the postgresql.conf for every system? or
Did you use the default configuration ?

Best wishes

On Fri, Sep 14, 2012 at 12:40 AM, Nikolay Ulyanitsky <lystor@gmail.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).

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?

Did you tell LKML? It seems like a kind of change that could be found
using git bisect of Linux, albiet laboriously.