kernel.git/arch/powerpc/platforms/pseries/processor_idle.c, branch linux-3.10.y

cpuidle: remove en_core_tk_irqen flag

2013-04-23T11:45:22Z

The en_core_tk_irqen flag is set in all the cpuidle driver which means it is not necessary to specify this flag. Remove the flag and the code related to it. Signed-off-by: Daniel Lezcano Acked-by: Kevin Hilman # for mach-omap2/* Signed-off-by: Rafael J. Wysocki

POWERPC: pseries: cpuidle: use time keeping flag

2013-04-08T20:20:06Z

The current code computes the idle time but that can be handled by the cpuidle framework if we enable the .en_core_tk_irqen flag. Set the flag and remove the code related to the time computation. Signed-off-by: Daniel Lezcano Signed-off-by: Deepthi Dharwar Signed-off-by: Rafael J. Wysocki

cpuidle: Measure idle state durations with monotonic clock

2012-11-27T13:17:58Z

Many cpuidle drivers measure their time spent in an idle state by reading the wallclock time before and after idling and calculating the difference. This leads to erroneous results when the wallclock time gets updated by another processor in the meantime, adding that clock adjustment to the idle state's time counter. If the clock adjustment was negative, the result is even worse due to an erroneous cast from int to unsigned long long of the last_residency variable. The negative 32 bit integer will zero-extend and result in a forward time jump of roughly four billion milliseconds or 1.3 hours on the idle state residency counter. This patch changes all affected cpuidle drivers to either use the monotonic clock for their measurements or make use of the generic time measurement wrapper in cpuidle.c, which was already working correctly. Some superfluous CLIs/STIs in the ACPI code are removed (interrupts should always already be disabled before entering the idle function, and not get reenabled until the generic wrapper has performed its second measurement). It also removes the erroneous cast, making sure that negative residency values are applied correctly even though they should not appear anymore. Signed-off-by: Julius Werner Reviewed-by: Preeti U Murthy Tested-by: Daniel Lezcano Acked-by: Daniel Lezcano Acked-by: Len Brown Signed-off-by: Rafael J. Wysocki

cpuidle/powerpc: Fix snooze state problem in the cpuidle design on pseries.

2012-10-17T23:57:25Z

Earlier without cpuidle framework on pseries, the native arch idle routine comprised of both snooze and nap states. smt_snooze_delay variable was used to delay the idle process entry to deeper idle state like nap. With the coming of cpuidle, this arch specific idle was replaced by two different idle routines, one for supporting snooze and other for nap. This enabled addition of more low level idle states on pseries in the future. On adopting the generic cpuidle framework for POWER systems, the decision of which idle state to choose from, given a predicted idle time is taken by the menu governor based on target_residency and exit_latency of the idle states. target_residency is the minimum time to be resident in that idle state. Exit_latency is time taken to exit out of idle state. Deeper the idle state, both the target residency and exit latency would be higher. In the current design, smt_snooze_delay is used as target_residency for the snooze state which is incorrect, as it is not the minimum but the maximum duration to be in snooze state. This would result in the governor in taking bad decision, as presently target_residency of nap < target_residency of snooze inspite of nap being deeper idle state. This patch aims to fix this problem by replacing the smt_snooze_delay loop in snooze state, with the need_resched() as the governor is aware of entry and exit of various idle transitions based on which next idle time prediction. The governor is intelligent enough to determine the idle state the needs to be transitioned to and maintains a whole of heuristics including io load, previous idle states predictions etc for the same, based on which idle state entry decision is taken. With this fix, of setting target_residency of snooze to 0 nap to smt_snooze_delay if the predicted idle time is less than smt_snooze_delay (target_residency of nap) value governor would pick snooze state, else nap. This adhers to the previous native idle design. Signed-off-by: Deepthi Dharwar Signed-off-by: Benjamin Herrenschmidt

cpuidle/powerpc: Fix smt_snooze_delay functionality.

2012-10-17T23:57:24Z

smt_snooze_delay was designed to delay idle loop's nap entry in the native idle code before it got ported over to use as part of the cpuidle framework. A -ve value assigned to smt_snooze_delay should result in busy looping, in other words disabling the entry to nap state. - https://lists.ozlabs.org/pipermail/linuxppc-dev/2010-May/082450.html This particular functionality can be achieved currently by echo 1 > /sys/devices/system/cpu/cpu*/state1/disable but it is broken when one assigns -ve value to the smt_snooze_delay variable either via sysfs entry or ppc64_cpu util. This patch aims to fix this, by disabling nap state when smt_snooze_delay variable is set to -ve value. Signed-off-by: Deepthi Dharwar Signed-off-by: Benjamin Herrenschmidt

cpuidle/powerpc: Fix target residency initialisation in pseries cpuidle

2012-10-17T23:57:24Z

Remove the redundant target residency initialisation in pseries_cpuidle_driver_init(). This is currently over-writing the residency time updated as part of the static table, resulting in all the idle states having the same target residency of 100us which is incorrect. This may result in the menu governor making wrong state decisions. Signed-off-by: Deepthi Dharwar Signed-off-by: Benjamin Herrenschmidt

powerpc/cpuidle: Fixes for pseries_idle hotplug notifier

2012-07-11T04:18:35Z

Currently the call to pseries_notify_cpuidle_add_cpu(), that takes action on the cpuidle front when a cpu is added/removed is being made from smp_xics_setup_cpu(). This caused lockdep issues as reported https://lkml.org/lkml/2012/5/17/2 On addition of each cpu, resources were cleared and re-allocated each time, all in critical section as part of start_secondary() call were interrupts are disabled. To resolve this issue, the pseries_notify_cpuidle_add_cpu() call is is being replaced by a hotplug notifier which would prevent cpuidle resources from being released and allocated each time cpu is onlined in the critical code path. It was fixed in https://lkml.org/lkml/2012/5/18/174. Also it is essential to call cpuidle_enable/disable_device between cpuidle_pause_and_lock() and cpuidle_resume_and_unlock() when used externally to avoid race conditions. Add support for CPU_ONLINE_FROZEN and CPU_DEAD_FROZEN as part of hotplug notify event for pseries_idle and unregister hotplug notifier while exiting out. The above mentioned issues are fixed as part of this patch. Signed-off-by: Deepthi Dharwar Signed-off-by: Benjamin Herrenschmidt

Merge branch 'merge' into next

2012-07-10T09:16:43Z

We want to bring in the latest IRQ fixes

powerpc: More fixes for lazy IRQ vs. idle

2012-07-10T09:16:07Z

Looks like we still have issues with pSeries and Cell idle code vs. the lazy irq state. In fact, the reset fixes that went upstream are exposing the problem more by causing BUG_ON() to trigger (which this patch turns into a WARN_ON instead). We need to be careful when using a variant of low power state that has the side effect of turning interrupts back on, to properly set all the SW & lazy state to look as if everything is enabled before we enter the low power state with MSR:EE off as we will return with MSR:EE on. If not, we have a discrepancy of state which can cause things to go very wrong later on. This patch moves the logic into a helper and uses it from the pseries and cell idle code. The power4/970 idle code already got things right (in assembly even !) so I'm not touching it. The power7 "bare metal" idle code is subtly different and correct. Remains PA6T and some hypervisor based Cell platforms which have questionable code in there, but they are mostly dead platforms so I'll fix them when I manage to get final answers from the respective maintainers about how the low power state actually works on them. Signed-off-by: Benjamin Herrenschmidt CC: stable@vger.kernel.org [v3.4]

powerpc/pseries/cpuidle: Replace pseries_notify_cpuidle_add call with notifier

2012-07-03T04:14:40Z

The following patch is to remove the pseries_notify_add_cpu() call and replace it by a hot plug notifier. This would prevent cpuidle resources being released and allocated each time cpu comes online on pseries. The earlier design was causing a lockdep problem in start_secondary as reported on this thread -https://lkml.org/lkml/2012/5/17/2 This applies on 3.4-rc7 Signed-off-by: Deepthi Dharwar Signed-off-by: Benjamin Herrenschmidt