kernel/linux.git/drivers/cpuidle, branch v4.17.1

cpuidle: menu: Avoid selecting shallow states with stopped tick

2018-04-09T09:54:57+00:00

If the scheduler tick has been stopped already and the governor selects a shallow idle state, the CPU can spend a long time in that state if the selection is based on an inaccurate prediction of idle time. That effect turns out to be relevant, so it needs to be mitigated. To that end, modify the menu governor to discard the result of the idle time prediction if the tick is stopped and the predicted idle time is less than the tick period length, unless the tick timer is going to expire soon. Signed-off-by: Rafael J. Wysocki Acked-by: Peter Zijlstra (Intel)

cpuidle: menu: Refine idle state selection for running tick

2018-04-09T09:54:56+00:00

If the tick isn't stopped, the target residency of the state selected by the menu governor may be greater than the actual time to the next tick and that means lost energy. To avoid that, make tick_nohz_get_sleep_length() return the current time to the next event (before stopping the tick) in addition to the estimated one via an extra pointer argument and make menu_select() use that value to refine the state selection when necessary. Signed-off-by: Rafael J. Wysocki Acked-by: Peter Zijlstra (Intel)

cpuidle: Return nohz hint from cpuidle_select()

2018-04-06T07:29:34+00:00

Add a new pointer argument to cpuidle_select() and to the ->select cpuidle governor callback to allow a boolean value indicating whether or not the tick should be stopped before entering the selected state to be returned from there. Make the ladder governor ignore that pointer (to preserve its current behavior) and make the menu governor return 'false" through it if: (1) the idle exit latency is constrained at 0, or (2) the selected state is a polling one, or (3) the expected idle period duration is within the tick period range. In addition to that, the correction factor computations in the menu governor need to take the possibility that the tick may not be stopped into account to avoid artificially small correction factor values. To that end, add a mechanism to record tick wakeups, as suggested by Peter Zijlstra, and use it to modify the menu_update() behavior when tick wakeup occurs. Namely, if the CPU is woken up by the tick and the return value of tick_nohz_get_sleep_length() is not within the tick boundary, the predicted idle duration is likely too short, so make menu_update() try to compensate for that by updating the governor statistics as though the CPU was idle for a long time. Since the value returned through the new argument pointer of cpuidle_select() is not used by its caller yet, this change by itself is not expected to alter the functionality of the code. Signed-off-by: Rafael J. Wysocki Acked-by: Peter Zijlstra (Intel)

cpuidle: poll_state: Avoid invoking local_clock() too often

2018-03-29T11:06:08+00:00

Rik reports that he sees an increase in CPU use in one benchmark due to commit 612f1a22f067 "cpuidle: poll_state: Add time limit to poll_idle()" that caused poll_idle() to call local_clock() in every iteration of the loop. Utilization increase generally means more non-idle time with respect to total CPU time (on the average) which implies reduced CPU frequency. Doug reports that limiting the rate of local_clock() invocations in there causes much less power to be drawn during a CPU-intensive parallel workload (with idle states 1 and 2 disabled to enforce more state 0 residency). These two reports together suggest that executing local_clock() on multiple CPUs in parallel at a high rate may cause chips to get hot and trigger thermal/power limits on them to kick in, so reduce the rate of local_clock() invocations in poll_idle() to avoid that issue. Fixes: 612f1a22f067 "cpuidle: poll_state: Add time limit to poll_idle()" Reported-by: Rik van Riel Reported-by: Doug Smythies Signed-off-by: Rafael J. Wysocki Tested-by: Rik van Riel Reviewed-by: Rik van Riel

PM: cpuidle/suspend: Add s2idle usage and time state attributes

2018-03-29T11:06:08+00:00

Add a new attribute group called "s2idle" under the sysfs directory of each cpuidle state that supports the ->enter_s2idle callback and put two new attributes, "usage" and "time", into that group to represent the number of times the given state was requested for suspend-to-idle and the total time spent in suspend-to-idle after requesting that state, respectively. That will allow diagnostic information related to suspend-to-idle to be collected without enabling advanced debug features and analyzing dmesg output. Signed-off-by: Rafael J. Wysocki

cpuidle: Enable coupled cpuidle support on Exynos3250 platform

2018-03-29T11:06:08+00:00

All the needed code has been already merged to mach-exynos core in commit af9971144dde ("ARM: EXYNOS: add coupled cpuidle support for Exynos3250"), so enable support for coupled variant also for Exynos3250 SoCs. Signed-off-by: Marek Szyprowski Acked-by: Krzysztof Kozlowski Acked-by: Bartlomiej Zolnierkiewicz Signed-off-by: Rafael J. Wysocki

cpuidle: poll_state: Add time limit to poll_idle()

2018-03-29T11:06:07+00:00

If poll_idle() is allowed to spin until need_resched() returns 'true', it may actually spin for a much longer time than expected by the idle governor, since set_tsk_need_resched() is not always called by the timer interrupt handler. If that happens, the CPU may spend much more time than anticipated in the "polling" state. To prevent that from happening, limit the time of the spinning loop in poll_idle(). Suggested-by: Peter Zijlstra Signed-off-by: Rafael J. Wysocki Tested-by: Doug Smythies

ARM: cpuidle: Drop memory allocation error message from arm_idle_init_cpu()

2018-03-05T11:39:32+00:00

Omit an extra message for a memory allocation failure in this function. This issue was detected by using the Coccinelle software. Signed-off-by: Markus Elfring Acked-by: Daniel Lezcano Signed-off-by: Rafael J. Wysocki

Merge tag 'powerpc-4.16-1' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux

2018-02-02T18:01:04+00:00

Pull powerpc updates from Michael Ellerman: "Highlights: - Enable support for memory protection keys aka "pkeys" on Power7/8/9 when using the hash table MMU. - Extend our interrupt soft masking to support masking PMU interrupts as well as "normal" interrupts, and then use that to implement local_t for a ~4x speedup vs the current atomics-based implementation. - A new driver "ocxl" for "Open Coherent Accelerator Processor Interface (OpenCAPI)" devices. - Support for new device tree properties on PowerVM to describe hotpluggable memory and devices. - Add support for CLOCK_{REALTIME/MONOTONIC}_COARSE to the 64-bit VDSO. - Freescale updates from Scott: fixes for CPM GPIO and an FSL PCI erratum workaround, plus a minor cleanup patch. As well as quite a lot of other changes all over the place, and small fixes and cleanups as always. Thanks to: Alan Modra, Alastair D'Silva, Alexey Kardashevskiy, Alistair Popple, Andreas Schwab, Andrew Donnellan, Aneesh Kumar K.V, Anju T Sudhakar, Anshuman Khandual, Anton Blanchard, Arnd Bergmann, Balbir Singh, Benjamin Herrenschmidt, Bhaktipriya Shridhar, Bryant G. Ly, Cédric Le Goater, Christophe Leroy, Christophe Lombard, Cyril Bur, David Gibson, Desnes A. Nunes do Rosario, Dmitry Torokhov, Frederic Barrat, Geert Uytterhoeven, Guilherme G. Piccoli, Gustavo A. R. Silva, Gustavo Romero, Ivan Mikhaylov, Joakim Tjernlund, Joe Perches, Josh Poimboeuf, Juan J. Alvarez, Julia Cartwright, Kamalesh Babulal, Madhavan Srinivasan, Mahesh Salgaonkar, Mathieu Malaterre, Michael Bringmann, Michael Hanselmann, Michael Neuling, Nathan Fontenot, Naveen N. Rao, Nicholas Piggin, Paul Mackerras, Philippe Bergheaud, Ram Pai, Russell Currey, Santosh Sivaraj, Scott Wood, Seth Forshee, Simon Guo, Stewart Smith, Sukadev Bhattiprolu, Thiago Jung Bauermann, Vaibhav Jain, Vasyl Gomonovych" * tag 'powerpc-4.16-1' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux: (199 commits) powerpc/mm/radix: Fix build error when RADIX_MMU=n macintosh/ams-input: Use true and false for boolean values macintosh: change some data types from int to bool powerpc/watchdog: Print the NIP in soft_nmi_interrupt() powerpc/watchdog: regs can't be null in soft_nmi_interrupt() powerpc/watchdog: Tweak watchdog printks powerpc/cell: Remove axonram driver rtc-opal: Fix handling of firmware error codes, prevent busy loops powerpc/mpc52xx_gpt: make use of raw_spinlock variants macintosh/adb: Properly mark continued kernel messages powerpc/pseries: Fix cpu hotplug crash with memoryless nodes powerpc/numa: Ensure nodes initialized for hotplug powerpc/numa: Use ibm,max-associativity-domains to discover possible nodes powerpc/kernel: Block interrupts when updating TIDR powerpc/powernv/idoa: Remove unnecessary pcidev from pci_dn powerpc/mm/nohash: do not flush the entire mm when range is a single page powerpc/pseries: Add Initialization of VF Bars powerpc/pseries/pci: Associate PEs to VFs in configure SR-IOV powerpc/eeh: Add EEH notify resume sysfs powerpc/eeh: Add EEH operations to notify resume ...

powerpc/pseries/cpuidle: add polling idle for shared processor guests

2018-01-18T04:43:44+00:00

For shared processor guests (e.g., KVM), add an idle polling mode rather than immediately returning to the hypervisor when the guest CPU goes idle. Test setup is a 2 socket POWER9 with 4 guests running, each with vCPUs equal to 1/2 of real of CPUs. Saturated each guest with tbench. Using polling idle gives about 1.4x throughput. Kernel compile speed was not changed significantly. Signed-off-by: Nicholas Piggin Signed-off-by: Michael Ellerman