[CentOS] CPU Usage when idle

sheraz naz sheraznaz at yahoo.com
Thu Jan 12 09:22:05 UTC 2012


--- On Wed, 1/11/12, Warren Young <warren at etr-usa.com> wrote:

From: Warren Young <warren at etr-usa.com>
Subject: Re: [CentOS] CPU Usage when idle
To: "CentOS mailing list" <centos at centos.org>
Date: Wednesday, January 11, 2012, 8:14 PM

On 1/11/2012 6:42 PM, Jorge Fábregas wrote:
>
> They did a great job with RHEL6 and I'm
> curious what was changed in order to accomplish this.

It's probably the PowerTop work, primarily done to get better battery 
life on laptops by throttling the CPU down when it's idle:

    http://www.lesswatts.org/projects/powertop/

powertop is just tool, similar to top command to see the top programs causing the cpu to wake up. I think the main improvement that Redhat themselves have provided is the use of tickless kernel. RHEL 5 used a periodic timer for each CPU causing it to wake up every few milliseonds to process events and thus never really entering idle state. The tickless kernel in RHEL6 allows the system to enter idle state more often. If you see system consuming too much power, you can install and run powertop to find the offending programs.

See section 1.2 in RHEL 6 power management guide.

Thanks
Sheraz










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