Public bug reported: There is an outstanding regression in i915 that breaks the RC6 power state for Intel iGPUs on Skylake and newer. This bug was fixed upstream in Linux 5.5. I submitted a backport of the fix for 5.4 upstream [1].
My cover letter [2] describes the issue: The first bug, fixed by "drm/i915/gt: Schedule request retirement when timeline idles" upstream, is very high power consumption by i915 hardware due to an old commit that broke the RC6 power state for the iGPU on Skylake+. On my laptop, a Dell Precision 5540 with an i9-9880H, the idle power consumption of my laptop with this commit goes down from 10 W to 2 W, saving a massive 8 W of power. On other Skylake+ laptops I tested, this commit reduced idle power consumption by at least a few watts. The difference in power consumption can be observed by running `powertop` while disconnected from the charger, or by using the intel-undervolt tool [1] and running `intel-undervolt measure` which doesn't require being disconnected from the charger. The psys measurement from intel-undervolt is the one of interest. Backporting this commit was not trivial due to i915's high rate of churn, but the backport didn't require changing any code from the original commit; it only required moving code around and not altering some #includes. [1] https://lore.kernel.org/stable/20200330033057.2629052-3-sul...@kerneltoast.com/ [2] https://lore.kernel.org/stable/20200330033057.2629052-1-sul...@kerneltoast.com/ ** Affects: linux (Ubuntu) Importance: Undecided Status: Incomplete ** Affects: linux (Ubuntu Focal) Importance: Undecided Status: Incomplete ** Also affects: linux Importance: Undecided Status: New ** No longer affects: lightdm (Ubuntu) ** Also affects: linux (Ubuntu) Importance: Undecided Status: New ** No longer affects: linux ** Also affects: linux (Ubuntu Focal) Importance: Undecided Status: New ** Description changed: There is an outstanding regression in i915 that breaks the RC6 power state for Intel iGPUs on Skylake and newer. This bug was fixed upstream in Linux 5.5. I submitted a backport of the fix for 5.4 upstream [1]. My cover letter [2] describes the issue: - The first bug, fixed by - "drm/i915/gt: Schedule request retirement when timeline idles" upstream, is very - high power consumption by i915 hardware due to an old commit that broke the RC6 - power state for the iGPU on Skylake+. On my laptop, a Dell Precision 5540 with - an i9-9880H, the idle power consumption of my laptop with this commit goes down - from 10 W to 2 W, saving a massive 8 W of power. On other Skylake+ laptops I - tested, this commit reduced idle power consumption by at least a few watts. The - difference in power consumption can be observed by running `powertop` while - disconnected from the charger, or by using the intel-undervolt tool [1] and - running `intel-undervolt measure` which doesn't require being disconnected from - the charger. The psys measurement from intel-undervolt is the one of interest. + The first bug, fixed by "drm/i915/gt: Schedule request retirement when timeline idles" upstream, is very high power consumption by i915 hardware due to an old commit that broke the RC6 power state for the iGPU on Skylake+. On my laptop, a Dell Precision 5540 with an i9-9880H, the idle power consumption of my laptop with this commit goes down from 10 W to 2 W, saving a massive 8 W of power. On other Skylake+ laptops I tested, this commit reduced idle power consumption by at least a few watts. The difference in power consumption can be observed by running `powertop` while disconnected from the charger, or by using the intel-undervolt tool [1] and running `intel-undervolt measure` which doesn't require being disconnected from the charger. The psys measurement from intel-undervolt is the one of interest. - Backporting this commit was not trivial due to i915's high rate of churn, but - the backport didn't require changing any code from the original commit; it only - required moving code around and not altering some #includes. - + Backporting this commit was not trivial due to i915's high rate of + churn, but the backport didn't require changing any code from the + original commit; it only required moving code around and not altering + some #includes. [1] https://lore.kernel.org/stable/20200330033057.2629052-3-sul...@kerneltoast.com/ [2] https://lore.kernel.org/stable/20200330033057.2629052-1-sul...@kerneltoast.com/ -- You received this bug notification because you are a member of Ubuntu Touch seeded packages, which is subscribed to lightdm in Ubuntu. https://bugs.launchpad.net/bugs/1869924 Title: High power consumption by Intel iGPU on Skylake+ Status in linux package in Ubuntu: Incomplete Status in linux source package in Focal: Incomplete Bug description: There is an outstanding regression in i915 that breaks the RC6 power state for Intel iGPUs on Skylake and newer. This bug was fixed upstream in Linux 5.5. I submitted a backport of the fix for 5.4 upstream [1]. My cover letter [2] describes the issue: The first bug, fixed by "drm/i915/gt: Schedule request retirement when timeline idles" upstream, is very high power consumption by i915 hardware due to an old commit that broke the RC6 power state for the iGPU on Skylake+. On my laptop, a Dell Precision 5540 with an i9-9880H, the idle power consumption of my laptop with this commit goes down from 10 W to 2 W, saving a massive 8 W of power. On other Skylake+ laptops I tested, this commit reduced idle power consumption by at least a few watts. The difference in power consumption can be observed by running `powertop` while disconnected from the charger, or by using the intel-undervolt tool [1] and running `intel-undervolt measure` which doesn't require being disconnected from the charger. The psys measurement from intel-undervolt is the one of interest. Backporting this commit was not trivial due to i915's high rate of churn, but the backport didn't require changing any code from the original commit; it only required moving code around and not altering some #includes. [1] https://lore.kernel.org/stable/20200330033057.2629052-3-sul...@kerneltoast.com/ [2] https://lore.kernel.org/stable/20200330033057.2629052-1-sul...@kerneltoast.com/ To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1869924/+subscriptions -- Mailing list: https://launchpad.net/~touch-packages Post to : touch-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~touch-packages More help : https://help.launchpad.net/ListHelp
