[Bugme-new] [Bug 16513] New: CPUs doesn't stay in deepest C-state with intel-idle
bugzilla-daemon at bugzilla.kernel.org
bugzilla-daemon at bugzilla.kernel.org
Wed Aug 4 03:55:20 PDT 2010
https://bugzilla.kernel.org/show_bug.cgi?id=16513
Summary: CPUs doesn't stay in deepest C-state with intel-idle
Product: Drivers
Version: 2.5
Kernel Version: 2.6.35
Platform: All
OS/Version: Linux
Tree: Mainline
Status: NEW
Severity: normal
Priority: P1
Component: Other
AssignedTo: drivers_other at kernel-bugs.osdl.org
ReportedBy: daniel at ekloef.se
Regression: No
Created an attachment (id=27340)
--> (https://bugzilla.kernel.org/attachment.cgi?id=27340)
Kernel log
When using the new intel-idle driver, the CPUs never reach 100% residency in
the deepest C-state. Instead, it's spread across C1-C4 (C4 being the deepest
C-state). Powertop also shows a large number of wakeups:
Cn Avg residency
C0 (cpu running) ( 0.0%)
polling 0.0ms ( 0.0%)
C1 mwait 61.8ms (24.5%)
C2 mwait 5.3ms (34.8%)
C4 mwait 0.8ms (41.1%)
P-states (frequencies)
1.67 Ghz 2.6%
1333 Mhz 0.1%
1000 Mhz 97.4%
Wakeups-from-idle per second : 595.0 interval: 15.0s
no ACPI power usage estimate available
Top causes for wakeups:
42.6% ( 12.2) [extra timer interrupt]
14.0% ( 4.0) [kernel core] usb_hcd_poll_rh_status (rh_timer_func)
9.8% ( 2.8) [i915] <interrupt>
When using the ACPI driver, things are also somewhat interresting; directly
after boot, there are no C-states available. After a couple of minutes (~3
minutes), the C-states become available (only up to C2 when running on AC, C4
when running on battery). At this point one can also see a large drop in power
usage.
So, to summarize:
acpi-idle: works, but it takes ~3 minutes for the C-states to become available
after boot
intel-idle: C-states are available right away, but something seems to be
interferring, and we are never able to stay in the deepest C-state (regardless
of how long time I wait).
intel-idle output:
Aug 4 12:16:07 lappy kernel: intel_idle: MWAIT substates: 0x20220
Aug 4 12:16:07 lappy kernel: intel_idle: v0.4 model 0x1C
Aug 4 12:16:07 lappy kernel: intel_idle: lapic_timer_reliable_states 0x6
Aug 4 12:16:07 lappy kernel: ACPI: acpi_idle yielding to intel_idle
Hardware: Samsung N150 (Atom N450), BIOS v.08JI
--
Configure bugmail: https://bugzilla.kernel.org/userprefs.cgi?tab=email
------- You are receiving this mail because: -------
You are on the CC list for the bug.
More information about the Bugme-new
mailing list