Messages in this thread | | | Subject | Re: [RFC PATCH 0/7] Introduce thermal pressure | From | Lukasz Luba <> | Date | Wed, 10 Oct 2018 17:35:50 +0200 |
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Hi Thara,
I have run it on Exynos5433 mainline. When it is enabled with step_wise thermal governor, some of my tests are showing ~30-50% regression (i.e. hackbench), dhrystone ~10%.
Could you tell me which thermal governor was used in your case? Please also share the name of that benchmark, i will give it a try. Is it single threaded compute-intensive?
Regards, Lukasz
On 10/09/2018 06:24 PM, Thara Gopinath wrote: > Thermal governors can respond to an overheat event for a cpu by > capping the cpu's maximum possible frequency. This in turn > means that the maximum available compute capacity of the > cpu is restricted. But today in linux kernel, in event of maximum > frequency capping of a cpu, the maximum available compute > capacity of the cpu is not adjusted at all. In other words, scheduler > is unware maximum cpu capacity restrictions placed due to thermal > activity. This patch series attempts to address this issue. > The benefits identified are better task placement among available > cpus in event of overheating which in turn leads to better > performance numbers. > > The delta between the maximum possible capacity of a cpu and > maximum available capacity of a cpu due to thermal event can > be considered as thermal pressure. Instantaneous thermal pressure > is hard to record and can sometime be erroneous as there can be mismatch > between the actual capping of capacity and scheduler recording it. > Thus solution is to have a weighted average per cpu value for thermal > pressure over time. The weight reflects the amount of time the cpu has > spent at a capped maximum frequency. To accumulate, average and > appropriately decay thermal pressure, this patch series uses pelt > signals and reuses the available framework that does a similar > bookkeeping of rt/dl task utilization. > > Regarding testing, basic build, boot and sanity testing have been > performed on hikey960 mainline kernel with debian file system. > Further aobench (An occlusion renderer for benchmarking realworld > floating point performance) showed the following results on hikey960 > with debain. > > Result Standard Standard > (Time secs) Error Deviation > Hikey 960 - no thermal pressure applied 138.67 6.52 11.52% > Hikey 960 - thermal pressure applied 122.37 5.78 11.57% > > Thara Gopinath (7): > sched/pelt: Add option to make load and util calculations frequency > invariant > sched/pelt.c: Add support to track thermal pressure > sched: Add infrastructure to store and update instantaneous thermal > pressure > sched: Initialize per cpu thermal pressure structure > sched/fair: Enable CFS periodic tick to update thermal pressure > sched/fair: update cpu_capcity to reflect thermal pressure > thermal/cpu-cooling: Update thermal pressure in case of a maximum > frequency capping > > drivers/base/arch_topology.c | 1 + > drivers/thermal/cpu_cooling.c | 20 ++++++++++++- > include/linux/sched.h | 14 +++++++++ > kernel/sched/Makefile | 2 +- > kernel/sched/core.c | 2 ++ > kernel/sched/fair.c | 4 +++ > kernel/sched/pelt.c | 40 ++++++++++++++++++-------- > kernel/sched/pelt.h | 7 +++++ > kernel/sched/sched.h | 1 + > kernel/sched/thermal.c | 66 +++++++++++++++++++++++++++++++++++++++++++ > kernel/sched/thermal.h | 13 +++++++++ > 11 files changed, 157 insertions(+), 13 deletions(-) > create mode 100644 kernel/sched/thermal.c > create mode 100644 kernel/sched/thermal.h >
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