Messages in this thread | | | From | Juri Lelli <> | Subject | [RFD PATCH 0/5] SCHED_DEADLINE freq/cpu invariance and OPP selection | Date | Fri, 24 Mar 2017 14:08:55 +0000 |
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Hi,
this is a very exploratory set implementing frequency/cpu invariance and OPP selection for SCHED_DEADLINE. The set has been slightly tested on a Juno platform. While the actual implementation is very premature, I'm posting this early to facilitate discussion at OSPM-summit [1].
Results of the testing, highlighting why these features are useful are available here:
- without the set https://gist.github.com/a6e3ee99cec32e00cc537b53cd3d54d2
- with the set https://gist.github.com/1f7d485fc3ce9234fe627dcb53b2935c
The set is based on tip/sched/core as of today (bc4278987e38) plus a couple of schedutil fixes coming from linux-pm/linux-next and Luca's "CPU reclaiming for SCHED_DEADLINE" v5 [2].
Patches high level description:
o [01-02]/05 add the necessary links to start accounting DEADLINE contribution to OPP selection o 03/05 it's an hack to make possible (on ARM) to change frequency for DEADLINE tasks (that would possibly delay the SCHED_FIFO worker kthread); suggestions on how to do this properly are very welcome o 04/05 it's a schedutil change that copes with the fact that DEADLINE doesn't require periodic OPP selection triggering point o 05/05 implements frequency/cpu invariance for tasks' reservation parameters*; which basically means that we implement GRUB-PA [3]
Please have a look. Feedback on how we want to shape this is the sole purpose of this posting.
In case you would like to test this out:
git://linux-arm.org/linux-jl.git upstream/deadline/freq-rfd
Best,
- Juri
[1] http://retis.sssup.it/ospm-summit/index.html [2] https://marc.info/?l=linux-kernel&m=149029880524038 [3] C. Scordino, G. Lipari, A Resource Reservation Algorithm for Power-Aware Scheduling of Periodic and Aperiodic Real-Time Tasks, IEEE Transactions on Computers, December 2006.
* Notice that this currently breaks !CONFIG_SMP, as arch_scale_{freq,cpu} _capacity and SCHED_CAPACITY_SCALE are only defined on CONFIG_SMP. Fixing this particular issue is straightforward, but we should probably look into making frequency scaling (and PELT averages) available on !CONFIG_SMP as well (so that schedutil can work on such configurations for example). Since this is only an RFD and since a proper rework might be non trivial, I decided to leave it out of scope for the time being.
Juri Lelli (5): sched/cpufreq_schedutil: make use of DEADLINE utilization signal sched/deadline: move cpu frequency selection triggering points sched/cpufreq_schedutil: make worker kthread be SCHED_DEADLINE sched/cpufreq_schedutil: always consider all CPUs when deciding next freq sched/deadline: make bandwidth enforcement scale-invariant
include/linux/sched.h | 1 + include/linux/sched/cpufreq.h | 2 -- include/uapi/linux/sched.h | 1 + kernel/sched/core.c | 19 +++++++++++++++++-- kernel/sched/cpufreq_schedutil.c | 37 ++++++++++++++++++++++--------------- kernel/sched/deadline.c | 40 +++++++++++++++++++++++++++++++++------- kernel/sched/fair.c | 2 -- kernel/sched/sched.h | 10 +++++++++- 8 files changed, 83 insertions(+), 29 deletions(-)
-- 2.10.0
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