Red Hat Bugzilla – Bug 815213
perf top reporst 9% in acpi_pm_read
Last modified: 2012-05-15 08:18:51 EDT
Description of problem:
acpi_pm_read seems to eat too much CPU time according with perf top.
Version-Release number of selected component (if applicable):
Steps to Reproduce:
Too much CPU usage by acpi_pm_read.
Much lower usage for acpi_pm_read.
Maybe is normal, but looks too big and the machine seems a bit sluggish. Hard to say when it started.
This is where time is spent:
99.51 : ffffffff814a9850: and $0xffffff,%eax
Intel(R) Core(TM)2 Duo CPU E8400 @ 3.00GHz
acpi pm timer is slow. there's no bug here.
I can understand that is slow, but 9%?!
I switched to tsc and it eats ~5%. Isn't it still too much?!
I run a perf and I generated the attached file. Seems that radeon eats a lot of resources in detecting DVI output. Monitor is connected on DVI.
radeon_dvi_detect appears a lot of time in the call stack.
Probably should be assigned to radeon.
Created attachment 584547 [details]
perf trace number 1