linux/drivers/cpuidle
Rafael J. Wysocki 4dc2375c1a cpuidle: poll_state: Avoid invoking local_clock() too often
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 <riel@surriel.com>
Reported-by: Doug Smythies <dsmythies@telus.net>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Tested-by: Rik van Riel <riel@surriel.com>
Reviewed-by: Rik van Riel <riel@surriel.com>
2018-03-29 13:06:08 +02:00
..
governors cpuidle: ladder: Add per CPU PM QoS resume latency support 2017-11-08 12:16:01 +01:00
coupled.c smp: Avoid using two cache lines for struct call_single_data 2017-08-29 15:14:38 +02:00
cpuidle-arm.c ARM: cpuidle: Drop memory allocation error message from arm_idle_init_cpu() 2018-03-05 12:39:32 +01:00
cpuidle-at91.c drivers/cpuidle: Convert non-modular drivers to use builtin_platform_driver 2015-06-16 14:12:38 -04:00
cpuidle-big_little.c ARM: MCPM: remove residency argument from mcpm_cpu_suspend() 2015-05-06 11:47:10 -04:00
cpuidle-calxeda.c ARM: migrate to common PSCI client code 2015-08-03 15:38:39 +01:00
cpuidle-clps711x.c drivers/cpuidle: make cpuidle-clps711x.c explicitly non-modular 2015-12-15 00:22:21 +01:00
cpuidle-cps.c Update MIPS email addresses 2017-11-03 09:02:30 -07:00
cpuidle-exynos.c cpuidle: Enable coupled cpuidle support on Exynos3250 platform 2018-03-29 13:06:08 +02:00
cpuidle-kirkwood.c ARM: cpuidle: Remove duplicate header inclusion 2015-03-23 18:03:11 +01:00
cpuidle-mvebu-v7.c cpuidle: mvebu: disable the bind/unbind attributes and use builtin_platform_driver 2015-10-23 12:40:48 +02:00
cpuidle-powernv.c cpuidle/powernv: avoid double irq enable coming out of idle 2018-01-18 15:43:43 +11:00
cpuidle-pseries.c powerpc/pseries/cpuidle: add polling idle for shared processor guests 2018-01-18 15:43:44 +11:00
cpuidle-ux500.c drivers/cpuidle: make cpuidle-ux500.c explicitly non-modular 2015-12-15 00:22:22 +01:00
cpuidle-zynq.c drivers/cpuidle: Convert non-modular drivers to use builtin_platform_driver 2015-06-16 14:12:38 -04:00
cpuidle.c PM: cpuidle/suspend: Add s2idle usage and time state attributes 2018-03-29 13:06:08 +02:00
cpuidle.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
driver.c cpuidle: Make drivers initialize polling state 2017-08-30 03:06:33 +02:00
dt_idle_states.c Merge branch 'pm-sleep' 2017-09-04 00:06:02 +02:00
dt_idle_states.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
governor.c cpuidle: Avoid NULL argument in cpuidle_switch_governor() 2018-01-05 14:01:30 +01:00
Kconfig cpuidle: Don't enable all governors by default 2016-01-15 22:39:58 +01:00
Kconfig.arm ARM: cpuidle: Support asymmetric idle definition 2017-06-24 01:51:00 +02:00
Kconfig.mips cpuidle: cpuidle-cps: Enable use with MIPSr6 CPUs. 2016-10-04 16:13:57 +02:00
Kconfig.powerpc powerpc/powernv/cpuidle: Back-end cpuidle driver for powernv platform. 2014-01-29 17:02:24 +11:00
Makefile License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
poll_state.c cpuidle: poll_state: Avoid invoking local_clock() too often 2018-03-29 13:06:08 +02:00
sysfs.c PM: cpuidle/suspend: Add s2idle usage and time state attributes 2018-03-29 13:06:08 +02:00