Hello kernel devs,
I am noticing a serious problem with the system timer flooding the bus with
many interrupts for no reason. I have compiled the kernel with tickless
enabled.
Can someone provide me some debugging to find out why this is happening?
As a comparsion my quad core box has no such issue: (Running 2.6.32-rc7)
x86_64
0: 42 4 1 1 IO-APIC-edge timer
my Lenovo ThinkPad W500 (latest BIOS 3.11) laptop shows the system timer
flooding the bus (Running 2.6.33-rc1) x86_64
0: 66775 70429 IO-APIC-edge timer<-- keeps rising, rapidly
and afew minutes ...
0: 119849 124505 IO-APIC-edge timer
Same for Rescheduling interrupts rising just as fast with the timer.
This does not look right, powertop shows:
40.0% ( 62.1)<kernel IPI> : Rescheduling interrupts
22.9% ( 35.6)<interrupt> : extra timer interrupt
17.0% ( 26.4)<interrupt> : iwlagn
and another sample...
54.6% (144.8)<kernel IPI> : Rescheduling interrupts
14.6% ( 38.8)<interrupt> : extra timer interrupt
8.5% ( 22.6)<interrupt> : iwlagn
6.5% ( 17.2)<interrupt> : uhci_hcd:usb6, radeon@pci:0000:01:00.0
6.5% ( 17.2) USB device 6-1 : Microsoft Basic Optical Mouse v2.0
(Microsoft )
There is no cause for the rescheduling interrupts and extra timer interrupt to
wakeup the CPUs so much? Are there any timer issues?