Bug 9807
| Summary: | ACPI processor idle driver creates /proc/acpi/processor/*/power although C2 or C3 isn't supported | ||
|---|---|---|---|
| Product: | ACPI | Reporter: | Yi Yang (yi.y.yang) |
| Component: | Power-Processor | Assignee: | acpi_power-processor |
| Status: | REJECTED DOCUMENTED | ||
| Severity: | normal | CC: | acpi-bugzilla, yi.y.yang |
| Priority: | P1 | ||
| Hardware: | All | ||
| OS: | Linux | ||
| Kernel Version: | 2.6.24-rc8 | Subsystem: | |
| Regression: | --- | Bisected commit-id: | |
| Attachments: | Fix patch for this bug | ||
Created attachment 14556 [details]
Fix patch for this bug
This patch fixes this issue, it make ACPI processor idle driver to create
proc entry only if the processor supports C2 or C3.
It is not a bug that the power file exists for systems with just C1. It is a bug that the C1 count does not increment on such systems -- a bug that venki is planning to fix the the benefit of powertop users. |
Latest working kernel version: None Earliest failing kernel version: All Distribution: FC8 Hardware Environment: All Software Environment: All Problem Description: ACPI processor idle driver makes sense only if the processor supports C2 or C3. For legacy C0 and C1, just the original pm_idle is working , statistics info about promotion, demotion, latency, usage and duration are empty or 0, so these are misleading, users'll think their CPUs support C states (C2 or C3), /proc/acpi/processor/CPU*/power shouldn't exist for this case at all. Steps to reproduce: [root@localhost ~]# dmesg | grep power [root@localhost ~]# cat /proc/acpi/processor/CPU0/info processor id: 0 acpi id: 1 bus mastering control: yes power management: no throttling control: yes limit interface: yes [root@localhost ~]# cat /proc/acpi/processor/CPU0/power active state: C0 max_cstate: C8 bus master activity: 00000000 maximum allowed latency: 2000 usec states: C1: type[C1] promotion[--] demotion[--] latency[000] usage[00000000] duration[00000000000000000000]