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Date: Thu, 30 Sep 2010 18:08:57 -0400 (EDT) From: Len Brown <lenb@...nel.org> To: Corrado Zoccolo <czoccolo@...il.com> Cc: Linux-Kernel <linux-kernel@...r.kernel.org>, Arjan van de Ven <arjan@...ux.intel.com> Subject: Re: 2.6.35.4: intel_idle has reduced residency in high C states. On Sun, 26 Sep 2010, Corrado Zoccolo wrote: > Hi Len, > I tested intel_idle on my Acer Aspire One netbook (Atom based), and > got lower residency in high C states compared to acpi_idle: > Immediately after boot, PowerTOP 1.11 reports for intel_idle: > Your CPU supports the following C-states : C1 C2 C4 > Your BIOS reports the following C-states : C1 C2 C4 > Cn Avg residency > C0 (cpu occupata) ( 2,3%) Corrado, differences in C2 vs C4 residency don't matter much when when the CPU is buy (C0) for 2 or 3% of the time. For an apples/apples comparison of intel_idle vs acpi_idle, CONFIG_INTEL_IDLE=y and boot with and without intel_idle.max_cstate=0 to run with acpi_idle and intel_idle, respectively. thanks, -Len Brown, Intel Open Source Technology Center > polling 0,0ms ( 0,0%) > C1 mwait 54,4ms (57,3%) > C2 mwait 1,7ms ( 2,8%) > C4 mwait 3,1ms (37,6%) > P-states (frequencies) > 1,60 Ghz 0,0% > 1333 Mhz 0,0% > 1066 Mhz 0,0% > 800 Mhz 100,0% > Wakeups-from-idle per second : 149,4 interval: 15,0s > no ACPI power usage estimate available > Top causes for wakeups: > 74,0% ( 98,5) <kernel core> : hrtimer_start_range_ns (tick_sched_timer) > 6,5% ( 8,7) <interrupt> : acpi > 4,0% ( 5,3) <kernel core> : hrtimer_start (tick_sched_timer) > 3,7% ( 4,9) <interrupt> : eth0 > 1,9% ( 2,5) X : __mod_timer (i915_hangcheck_elapsed) > 1,5% ( 2,0) lxpanel : hrtimer_start_range_ns (hrtimer_wakeup) > 1,3% ( 1,7) lxterminal : hrtimer_start_range_ns (hrtimer_wakeup) > 1,0% ( 1,3) lxpanel : __mod_timer (process_timeout) > 0,8% ( 1,1) <kernel IPI> : TLB shootdowns > 0,8% ( 1,0) ifplugd : hrtimer_start_range_ns (hrtimer_wakeup) > 0,7% ( 0,9) X : queue_delayed_work (delayed_work_timer_fn) > > while for acpi_idle: > Cn Avg residency > C0 (cpu occupata) ( 2,1%) > polling 0,0ms ( 0,0%) > C1 halt 0,1ms ( 0,0%) > C2 11,9ms (14,7%) > C3 12,1ms (83,2%) > P-states (frequencies) > 1,60 Ghz 0,0% > 1333 Mhz 0,0% > 1066 Mhz 0,3% > 800 Mhz 99,7% > Wakeups-from-idle per second : 81,2 interval: 15,0s > no ACPI power usage estimate available > Top causes for wakeups: > 60,3% ( 92,3) <kernel core> : hrtimer_start_range_ns (tick_sched_timer) > 12,4% ( 18,9) <interrupt> : extra timer interrupt > 5,9% ( 9,0) <kernel IPI> : Rescheduling interrupts > 5,6% ( 8,6) <interrupt> : acpi > 3,4% ( 5,2) <interrupt> : eth0 > 2,7% ( 4,1) <kernel core> : hrtimer_start (tick_sched_timer) > 1,6% ( 2,4) X : __mod_timer (i915_hangcheck_elapsed) > 1,3% ( 2,0) lxpanel : hrtimer_start_range_ns (hrtimer_wakeup) > 1,2% ( 1,8) lxpanel : __mod_timer (process_timeout) > 1,1% ( 1,7) lxterminal : hrtimer_start_range_ns (hrtimer_wakeup) > 0,7% ( 1,0) ifplugd : hrtimer_start_range_ns (hrtimer_wakeup) > 0,6% ( 0,9) X : queue_delayed_work (delayed_work_timer_fn) > 0,3% ( 0,5) <kernel core> : enqueue_task_rt (sched_rt_period_timer) > 0,3% ( 0,5) <kernel IPI> : TLB shootdowns > > This may be unrelated, but I noticed that compared with 2.6.34, the > load average immediately after boot is higher for 2.6.35.4 (and > decreases more slowly). This gives a higher multiplier in the menu > governor, so the residency numbers for 2.6.34 with acpi_idle are again > different: > Cn Avg residency > C0 (cpu occupata) ( 3,2%) > polling 0,0ms ( 0,0%) > C1 halt 0,1ms ( 0,0%) > C2 7,9ms (10,5%) > C3 11,7ms (86,3%) > P-states (frequencies) > 1,60 Ghz 0,0% > 1333 Mhz 0,0% > 1066 Mhz 0,9% > 800 Mhz 99,1% > Wakeups-from-idle per second : 87,1 interval: 15,0s > no ACPI power usage estimate available > Top causes for wakeups: > 67,1% (130,0) <kernel core> : hrtimer_start_range_ns (tick_sched_timer) > 8,7% ( 16,9) <interrupt> : extra timer interrupt > 6,5% ( 12,5) <kernel IPI> : Rescheduling interrupts > 4,5% ( 8,7) <interrupt> : acpi > 2,3% ( 4,5) <kernel core> : hrtimer_start (tick_sched_timer) > 1,9% ( 3,7) <interrupt> : eth0 > 1,4% ( 2,7) X : __mod_timer (i915_hangcheck_elapsed) > 1,0% ( 2,0) lxpanel : hrtimer_start_range_ns (hrtimer_wakeup) > 0,9% ( 1,8) lxpanel : __mod_timer (process_timeout) > 0,9% ( 1,7) lxterminal : hrtimer_start_range_ns (hrtimer_wakeup) > 0,5% ( 1,0) ifplugd : hrtimer_start_range_ns (hrtimer_wakeup) > 0,4% ( 0,8) <interrupt> : ehci_hcd:usb1, uhci_hcd:usb2, > i915@pci:0000:00:02.0 > 0,4% ( 0,7) <interrupt> : ata_piix > 0,4% ( 0,7) X : queue_delayed_work (delayed_work_timer_fn) > The numbers for 2.6.34 look more sensible (avg residency in C2 << avg > residency in C3), so it may be good to re-evaluate the factors in menu > governor. > > Thanks, > Corrado > > --- > __________________________________________________________________________ > > dott. Corrado Zoccolo mailto:czoccolo@...il.com > PhD - Department of Computer Science - University of Pisa, Italy > -------------------------------------------------------------------------- > The self-confidence of a warrior is not the self-confidence of the average > man. The average man seeks certainty in the eyes of the onlooker and calls > that self-confidence. The warrior seeks impeccability in his own eyes and > calls that humbleness. > Tales of Power - C. Castaneda >
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