--- On Wed, 1/11/12, Warren Young warren@etr-usa.com wrote:
From: Warren Young warren@etr-usa.com Subject: Re: [CentOS] CPU Usage when idle To: "CentOS mailing list" centos@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