Red Hat Bugzilla – Bug 455447
FEAT: RHEL 5.3: (1/2) Increase deep idle state residency on idle platforms using Nehalem class processors
Last modified: 2015-05-08 10:03:07 EDT
1. Feature Name: Increase deep idle state residency on idle platforms using Nehalem class processors 2. Description: Architectures (mark all that apply) x 32-bit x86 64-bit Itanium2 x 64-bit Intel EM64T Dependencies: External links: Priority (H,M,L): H Target Releases: Target Release Date: Drivers or hardware dependency: Target Kernel: 3. Business Justification: a. Why is this feature needed? Big power efficiency improvement. Have seen savings of approximately 7-8%. b. What hardware does this enable? Nehalem CPUs c. Forecast, volume or high end platform? Volume d. Any configuration info? e. When needed? f. Are there other dependencies (drivers). 4. Status: a. Is code accepted upstream? If so, what version or patch? Will add to bug info 5. Hardware to Red Hat? Red Hat can't integrate/test features without hardware. Tylersburg-EP systems can be used to test this. 6. Partner management contact, email, phone, chat keve.a.gabbert@intel.com 7. Partner technical contact, email, phone, chat jvillalo@redhat.com
I am going to attach the simpler patch to this bug. Together the two patches increase the deep idle state residency on an idle platform and performance/power team folks found >16W savings with these two patches out of total 220W idle power, which is 7-8%. Of the two patches, first one is simpler and bigger savings and should be easier to push.
Created attachment 311847 [details] Patch for this bug
Applying this and 455449, I'm not obviously seeing any increase in C3 residency (using powertop as a measuring tool). Is there a recommended way to perform this measurement?
Venki, Can you answer the question about C3 residency?
in kernel-2.6.18-113.el5 You can download this test kernel from http://people.redhat.com/dzickus/el5
Partners, this bug should be fixed in the latest RHEL 5.3 Snapshot. We believe that you have some interest in its correct functionality, so we're making a friendly request to send us some testing feedback. If you have a chance to test it, please share with us your findings. If you have successfully VERIFIED the fix, please add PartnerVerified to the Bugzilla keywords, along with a description of the results. Thanks!
Verify on Tylersburg EP, the bug was fixed.
An advisory has been issued which should help the problem described in this bug report. This report is therefore being closed with a resolution of ERRATA. For more information on therefore solution and/or where to find the updated files, please follow the link below. You may reopen this bug report if the solution does not work for you. http://rhn.redhat.com/errata/RHSA-2009-0225.html