Related - I2C Trackpads and other IRQ mechanisms have trouble on Intel Hybrid platforms. Handle them with lpmd
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Assessment
- Difficulty
- 5/5
- Estimated time
- Over a week
- Newbie friendliness
- 25/100
- Issue type
- Feature
- Clarity
- Mostly clear
- Activity status
- Stale
- Tech stack
- c, linux
- Domain
- operating-systems, performance
Research direction
Start by reading the existing IRQ and core-pinning handling in intel-lpmd, then review the linked kernel bug 218169 for the I2C trackpad behavior. The work is complete when related interrupts avoid parked cores in low-power mode and remain within the same core cluster, with validation on affected Intel hybrid platforms.
Written by the indexing model from the issue text.
Description
One of the biggest power managements issues I've noticed with Alder Lake/Raptor Lake platforms is IRQs getting suboptimal core pinning.
A great example with this is I2C trackpads/touchpads, as seen on https://bugzilla.kernel.org/show_bug.cgi?id=218169.
Moving the finger on the touchpad generates two kinds of interrupts, which are pinned to topologically unrelated cores by the kernel (one interrupt is handled by a P core, another is handled by an E core). This has a very big hit on power consumption.
intel-lpmd could be used in cases like these to pin interrupts to the most optimal cores:
- When on low-power mode, avoid handling interrupts in parked cores. This ensures that the cores actually remain parked.
- Avoid handling related interrupts outside of the same cluster. (P-core, E-core(1-4), E-core(5,8), etc.). This ensures that consistent actions such as using the trackpad do not wake up more than one cluster.
- Dominant language
- C
- Stars
- 225
- Forks
- 33
- Avg merge
- 2m
- Merged PRs (30d)
- 2
Getting set up
- No Dockerfile or Docker Compose file
- No pull request template
- Read the contributing guide
First steps
- Read the whole issue, then the project's contributing guide.
- Comment on the issue to say you are picking it up — it saves two people doing the same work.
- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
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