Re: pg9.0.3 explain analyze running very slow compared to a different box with much less configuration

If it's a HP box you can also turn this off via the bios via your RBSU:

Starting with HP ProLiant G6 servers that utilize Intel® Xeon® processors, setting the HP Power Profile 
Option in RBSU to Maximum Performance Mode sets these recommended additional low-latency options 
for minimum BIOS latenc


-----Original Message-----
From: pgsql-performance-owner@postgresql.org [mailto:pgsql-performance-owner@postgresql.org] On Behalf Of Marti
Raudsepp
Sent: Friday, March 25, 2011 3:30 AM
To: DM
Cc: Achilleas Mantzios; pgsql-performance@postgresql.org
Subject: Re: [PERFORM] pg9.0.3 explain analyze running very slow compared to a different box with much less
configuration

2011/3/25 DM <dm.aeqa@gmail.com>:
> gettimeofday() on my new box is slow, after further research we found 
> that, when we set ACPI=Off, we got a good clock performance even the 
> explain analyze gave approximately gave the right values, but the 
> hyperthreading is off.

Disabling ACPI also disables most CPU power management, so that explains why you get a stable TSC that way. But that's
nota real fix.
 

> could you guide me how to set, the parameter current_clocksource to 
> TSC,

You can't "set" it, the kernel will automatically choose TSC, if it's stable, at boot time; see messages in dmesg.

A better way to disable power management on CentOS is to disable the 'cpuspeed' service.

Note that this is not necessary for newer CPUs; Intel Nehalem and AMD Phenom series have a stable TSC even with power
managementenabled.
 

Regards,
Marti

--
Sent via pgsql-performance mailing list (pgsql-performance@postgresql.org)
To make changes to your subscription:
http://www.postgresql.org/mailpref/pgsql-performance

This communication is for informational purposes only. It is not
intended as an offer or solicitation for the purchase or sale of
any financial instrument or as an official confirmation of any
transaction. All market prices, data and other information are not
warranted as to completeness or accuracy and are subject to change
without notice. Any comments or statements made herein do not
necessarily reflect those of JPMorgan Chase & Co., its subsidiaries
and affiliates.

This transmission may contain information that is privileged,
confidential, legally privileged, and/or exempt from disclosure
under applicable law. If you are not the intended recipient, you
are hereby notified that any disclosure, copying, distribution, or
use of the information contained herein (including any reliance
thereon) is STRICTLY PROHIBITED. Although this transmission and any
attachments are believed to be free of any virus or other defect
that might affect any computer system into which it is received and
opened, it is the responsibility of the recipient to ensure that it
is virus free and no responsibility is accepted by JPMorgan Chase &
Co., its subsidiaries and affiliates, as applicable, for any loss
or damage arising in any way from its use. If you received this
transmission in error, please immediately contact the sender and
destroy the material in its entirety, whether in electronic or hard
copy format. Thank you.

Please refer to http://www.jpmorgan.com/pages/disclosures for
disclosures relating to European legal entities.