Re: Linux filesystem performance and checkpoint sorting

Josh Berkus wrote:
> So: Linux flavor? Kernel version? Disk system and PG directory layout?
>

OS configuration and PostgreSQL settings are saved into the output from
the later runs (I added that somewhere in the middle):

http://www.2ndquadrant.us/pgbench-results/294/pg_settings.txt

That's Ubuntu 10.04, kernel 2.6.32.

There is a test rig bug that queries the wrong PostgreSQL settings in
the later ones, but they didn't change after #294 here. The kernel
configuration stuff is accurate through, which confirms exactly what
settings for the dirty_* parameters was effective for each during the
tests I was changing those around.

16GB of RAM, 8 Hyperthreaded cores (4 real ones) via Intel i7-870.
Areca ARC-1210 controller, 256MB of cache.

Filesystem 1K-blocks Used Available Use% Mounted on
/dev/sda1 40G 7.5G 30G 20% /
/dev/md1 838G 15G 824G 2% /stripe
/dev/sdd1 149G 2.1G 147G 2% /xlog

/stripe is a 3 disk RAID0, setup to only use the first section of the
drive ("short-stroked"). That makes its performance a little more like
a small SAS disk, rather than the cheapo 7200RPM SATA drives they
actually are (Western Digital 640GB WD6400AAKS-65A7B). /xlog is a
single disk, 160GB WD1600AAJS-00WAA. OS, server logs, and test results
information all go to the root filesystem on a different drive. My aim
was to get similar performance to what someone with an 8-disk RAID10
array might see, except without the redundancy. Basic entry-level
database server here in 2011.

bonnie++ on the main database disk: read 301MB/s write 215MB/s, seeks
423.4/second. Measured around 10K small commits/second to prove the
battery-backed write cache works fine.

--
Greg Smith 2ndQuadrant US greg(at)2ndQuadrant(dot)com Baltimore, MD
PostgreSQL Training, Services, and 24x7 Support www.2ndQuadrant.us
"PostgreSQL 9.0 High Performance": http://www.2ndQuadrant.com/books