Red Hat Bugzilla – Bug 437672
1000Hz timer still active on tickless kernel
Last modified: 2008-03-15 23:23:22 EDT
Description of problem: Powertop reports that a 1000Hz timer is still active.
This prevents the CPU from sleeping.
Version-Release number of selected component (if applicable): kernel-126.96.36.199-12.fc8
How reproducible: Always
Steps to Reproduce:
1. Boot Kernel
2. Sit at idle
Actual results: ~1600 wakeups
Expected results: ~500 or lower wakeups
Additional info: Attaching lspci, dmesg, and powertop outputs.
This does not happen on my Pentium 4 3ghz HT-enabled 32-bit machine. Same
Created attachment 298174 [details]
Created attachment 298175 [details]
Created attachment 298176 [details]
it's because of the IR receiver on your TV card. AFAICT, this is a limitation
of the hardware (it doesn't appear to send an interrupt when it receives an IR
event, so the kernel has to poll frequently to see if something happened). If
we lower the polling frequency, we may end up missing events.