Messages in this thread | | | Date | Fri, 07 Dec 2007 23:56:00 -0500 | From | Ed Sweetman <> | Subject | Re: x86_64 dynticks not working prev: cpuidle, dynticks compatible or no? |
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Robert Hancock wrote: > Ed Sweetman wrote: >> System is idle now, previously it was doing something i couldn't halt >> at the time. I'm looking at "Local timer interrupts" in the "Loc:" >> section of /proc/interrupts. >> Across 1 second while the system is pretty much idle, i still get 300 >> interrupts. My HZ variable is set to 300 in the kernel config, so >> this is expected but I was under the assumption that >> dynticks/tickless being compiled in would cause that to be much lower. >> >> Am I reading the wrong section of /proc/interrupts to verify if >> dynticks is working or not? Again, i see no difference in cpu temp at >> all. > > Try running powertop ( http://www.lesswatts.org/projects/powertop/ ) > and see what it reports. > > I don't think dynticks will generally save huge amounts of power on a > typical desktop machine. The big gains come from being able to stay in > deep sleep C-states (C2/C3) for longer periods of time, but most > desktop machines only enable sleep states down to C1. > I tried running powertop, it complains about not having timer statistics, I looked throughout the kernel config for a timer stat option, but can't find one.
I didn't have hpet compiled in, i'm not sure if this is required but a lot of places seem to suggest hpet and high precision timer and tickless be compiled together. I also disabled cpuidle and i'll reboot and try that.
>> >> In case it helps, this is an athlon64 x2 with apic functioning and >> both cores active in 64bit mode. dmesg is below. >> not related : >> Some additional notes: it87 is my lm_sensor, it doesn't work in this >> kernel, yet it did in 2.6.22. Perhaps enabling high precision timers >> changed something in acpi land. >> >> I enabled tcp dma offloading in this kernel, i get debugging output >> related to it, error is at the last line. No corruption or otherwise >> bad behavior. Transferring via cifs at 9.7MB/sec "incoming" took >> about 15% of one cpu... I never bothered to check if that is the >> norm but i suspect i'll be removing that feature as it seems to not >> play nice with the kernel. >
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