Colin, I read that you were considering[1] enabling it during t+1 and I wanted your opinion for enabling it in Trusty on EC2 images at this time. Also, what testing were you doing to evaluate this previously? Thanks.
[1] https://lists.ubuntu.com/archives/kernel-team/2014-April/040795.html -- You received this bug notification because you are a member of Kernel Packages, which is subscribed to linux-meta in Ubuntu. https://bugs.launchpad.net/bugs/1477171 Title: Enable intel_pstate by default on Trusty EC2 AMIs Status in linux package in Ubuntu: New Bug description: Please can the intel_pstate driver be enabled by default on the Ubuntu EC2 AMIs. On instances with support for C-states and P-States [1] there is a notable performance impact and lack of support for higher clock frequencies available due to the use of the acpi-cpufreq driver. For example on a c4.8xlarge the default frequency is limited to 2.9GHz when 3.2GHz is supported by the chip [2]. Some additional analysis is available here [3] and re-enabling it by default has been discussed [4] but this request is specifically for the EC2 AMIs. [1] http://docs.aws.amazon.com/AWSEC2/latest/UserGuide/processor_state_control.html [2] http://docs.aws.amazon.com/AWSEC2/latest/UserGuide/c4-instances.html [3] http://www.deplication.net/2015/07/c-states-and-p-states-with-ubuntu-1404.html [4] https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1188647 AMI: ami-47a23a30 (eu-west-1) $ lsb_release -d Description: Ubuntu 14.04.2 LTS $ uname -a Linux ip-172-31-8-218 3.13.0-57-generic #95-Ubuntu SMP Fri Jun 19 09:28:15 UTC 2015 x86_64 x86_64 x86_64 GNU/Linux Default configuration (c4.8xl): $ sudo cpupower frequency-info analyzing CPU 0: driver: acpi-cpufreq CPUs which run at the same hardware frequency: 0 CPUs which need to have their frequency coordinated by software: 0 maximum transition latency: 10.0 us. hardware limits: 1.20 GHz - 2.90 GHz available frequency steps: 2.90 GHz, 2.90 GHz, 2.80 GHz, 2.70 GHz, 2.50 GHz, 2.40 GHz, 2.30 GHz, 2.20 GHz, 2.00 GHz, 1.90 GHz, 1.80 GHz, 1.70 GHz, 1.60 GHz, 1.40 GHz, 1.30 GHz, 1.20 GHz available cpufreq governors: conservative, ondemand, userspace, powersave, performance current policy: frequency should be within 1.20 GHz and 2.90 GHz. The governor "ondemand" may decide which speed to use within this range. current CPU frequency is 1.20 GHz (asserted by call to hardware). cpufreq stats: 2.90 GHz:70.40%, 2.90 GHz:0.00%, 2.80 GHz:0.00%, 2.70 GHz:0.00%, 2.50 GHz:0.00%, 2.40 GHz:0.00%, 2.30 GHz:0.00%, 2.20 GHz:0.00%, 2.00 GHz:0.00%, 1.90 GHz:0.00%, 1.80 GHz:0.00%, 1.70 GHz:0.00%, 1.60 GHz:0.09%, 1.40 GHz:0.00%, 1.30 GHz:0.00%, 1.20 GHz:29.51% (5) boost state support: Supported: yes Active: yes With intel_pstate enabled (c4.8xl): $ sudo cpupower frequency-info analyzing CPU 0: driver: intel_pstate CPUs which run at the same hardware frequency: 0 CPUs which need to have their frequency coordinated by software: 0 maximum transition latency: 0.97 ms. hardware limits: 1.20 GHz - 3.50 GHz available cpufreq governors: performance, powersave current policy: frequency should be within 1.20 GHz and 3.50 GHz. The governor "performance" may decide which speed to use within this range. current CPU frequency is 3.20 GHz (asserted by call to hardware). boost state support: Supported: yes Active: yes To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1477171/+subscriptions -- Mailing list: https://launchpad.net/~kernel-packages Post to : kernel-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~kernel-packages More help : https://help.launchpad.net/ListHelp
