Numerous proposals for various changes to per-entity load-tracking have been posted in the past to introduce various forms of scale invariance, utilization tracking, and taking blocked load into account. This RFC patch set has attempts to merge the features of these proposals.
The patch set is based on top of Vincent's cpu capacity and usage patch set [1] which introduces the scheduler side of frequency invariant utilization tracking. This patch set adds: Patches: 1: Adds frequency scale invariance to runnable load tracking (weighted_cpuload() and friends). Like utilization in [1], load is now also scaled with frequency relative to the max frequency. 2: Adds cpu scale invariance to both load and utilization. This second scaling compensates for differences in max performance between cpus, e.g. cpus with different max OPPs or different cpu uarchs (ARM big.LITTLE). 3-5: ARM arch implementation of arch_scale_freq_capacity() to enable frequency invariance of both utilization and load. 6: Update ARM arch implementation of arch_scale_cpu_capacity(). 7: Remove scaling of cpu usage by capacity_orig. With introduction of cpu scale-invariance the per-entity tracking already does this scaling. Experimental patches: 8: Add tracking of blocked utilization (usage) to the utilization introduced in [1]. 9: Change get_cpu_usage() to include blocked utilization (usage). 10: Change weighted_cpuload() to include blocked load. The implications of this change needs further testing and very likely more changes. The last three patches are quite likely to cause some trouble and require some modifications to the users of get_cpu_usage() and weighted_cpuload(). An audit of the load-balance code is needed. The blocked load/utilization patches should be considered experimental, but they are part of what is needed to add invariance and blocked load/utilization to per-entity load-tracking. The purpose of this whole exercise is to get more accurate load and utilization tracking for systems with frequency scaling and/or cpus with different uarchs. [1] https://lkml.org/lkml/2014/11/3/535 Dietmar Eggemann (5): sched: Make load tracking frequency scale-invariant sched: Make usage and load tracking cpu scale-invariant ARM: vexpress: Add CPU clock-frequencies to TC2 device-tree arm: Cpu invariant scheduler load-tracking support sched: Get rid of scaling usage by cpu_capacity_orig Morten Rasmussen (5): cpufreq: Architecture specific callback for frequency changes arm: Frequency invariant scheduler load-tracking support sched: Track blocked utilization contributions sched: Include blocked utilization in usage tracking sched: Include blocked load in weighted_cpuload arch/arm/boot/dts/vexpress-v2p-ca15_a7.dts | 5 ++ arch/arm/kernel/topology.c | 97 +++++++++++++++++------------- drivers/cpufreq/cpufreq.c | 10 ++- kernel/sched/fair.c | 91 ++++++++++++++++++++++------ kernel/sched/sched.h | 8 ++- 5 files changed, 147 insertions(+), 64 deletions(-) -- 1.9.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
