Re: Linux vs FreeBSD

As a side note, when we migrated the exact same pgsql 8.3 system from linux kernel 2.6 to 3.6,
we experienced an almost dramatic slowdown by 6 times.
Linux Kernel's were known to have issues around those dates, i recall.
We had to set synchronous_commit to off, this gave a huge boost ,
but this was no longer "apples" vs "apples".

On 04/04/2014 07:03, François Beausoleil wrote:
> Hi all!
>
> Does PG perform that much better on FreeBSD? I have some performance issues on a Ubuntu 12.04 which I'd like to resolve. iowait varies a lot, between 5 and 50%. Does FreeBSD better schedule I/O, which could alleviate some of the issues, or not at all? I have no experience administering FreeBSD, but I'm willing to learn if I'll get some performance enhancements out of the switch.
>
> Our workload is lots of data import, followed by many queries to summarize (daily and weekly reports). Our main table is a wide table that represents Twitter and Facebook interactions. Most of our reports work on a week's worth of data (table is partitioned by week), and the tables are approximately 25 GB plus 5 GB of indices, per week. Of course, while reports are ongoing, we're also importing next week's data.
>
> The host is a dedicated hardware machine at online.fr: 128 GB RAM, 2 x 3TB disk in RAID 1 configuration.
>
> I started thinking of this after reading "PostgreSQL pain points" at https://lwn.net/Articles/591723/. In the comments, bronson says FreeBSD does not exhibit the same problems (slow fsync, double buffering). On the list here, I've read about problems with certain kernel versions on Ubuntu.
>
> I'm not expecting anything magical, just some general guidelines and hints. Did anybody do the migration and was happier after?
>
> Thanks for any hints!
> François Beausoleil
>
> $ uname -a
> Linux munn.ca.seevibes.com 3.2.0-58-generic #88-Ubuntu SMP Tue Dec 3 17:37:58 UTC 2013 x86_64 x86_64 x86_64 GNU/Linux
>
> $ psql -U postgres -c "select version()"
>                                                     version
> -------------------------------------------------------------------------------------------------------------
>   PostgreSQL 9.1.11 on x86_64-unknown-linux-gnu, compiled by gcc (Ubuntu/Linaro 4.6.3-1ubuntu5) 4.6.3, 64-bit
>
> /proc/cpuinfo says: 8 CPUs, identified as "Intel(R) Xeon(R) CPU E5-2609 0 @ 2.40GHz"
>


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Achilleas Mantzios
Head of IT DEV
IT DEPT
Dynacom Tankers Mgmt