[RFC PATCH v1 0/8] SCHED_DEADLINE freq/cpu invariance and OPP selection

Juri Lelli
2017-07-05T09:00:15Z

Hi,

v1 of the RFC set implementing frequency/cpu invariance and OPP selection for
SCHED_DEADLINE [1]. The set is based on tip/sched/core as of today
(72298e5c92c5), which now already includes Luca's "CPU reclaiming for
SCHED_DEADLINE".

Thanks a lot for reviewing RFCv0!

Patches high level description:

o [01-02]/08 add the necessary links to start accounting DEADLINE contribution
to OPP selection
o 03/08 it's a temporary solution to make possible (on ARM) to change
frequency for DEADLINE tasks (that would possibly delay the SCHED_FIFO
worker kthread); proper solution would be to be able to issue frequency
transition from an atomic ctx
o [04-05]/08 it's a schedutil change that copes with the fact that DEADLINE
doesn't require periodic OPP selection triggering point
o [06-07]/08 make arch_scale_{freq,cpu}_capacity() function available on !CONFIG_SMP
configurations too
o 08/08 implements frequency/cpu invariance for tasks' reservation
parameters; which basically means that we implement GRUB-PA [2]

Changes w.r.t. RFCv0:

- rebase on tip/sched/core
- make use of BW_SHIFT for calculations (Peter)
- added a comment about guaranteed/requested frequency (Peter)
- use a high bit for sched_flags SCHED_FLAG_SPECIAL hack; don't expose it to
userspace and add comments (Peter)
- refactor aggregation of utilization from scheduling classes

Please have a look. Feedback and comments are, as usual, more than welcome.

In case you would like to test this out:

git://linux-arm.org/linux-jl.git upstream/deadline/freq-rfc-v1

Best,

- Juri

Juri Lelli (8):
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: split utilization signals
sched/cpufreq_schedutil: always consider all CPUs when deciding next
freq
sched/sched.h: remove sd arch_scale_freq_capacity parameter
sched/sched.h: move arch_scale_{freq,cpu}_capacity outside CONFIG_SMP
sched/deadline: make bandwidth enforcement scale-invariant

include/linux/sched.h | 1 +
include/linux/sched/cpufreq.h | 2 --
include/linux/sched/topology.h | 12 +++----
kernel/sched/core.c | 15 ++++++--
kernel/sched/cpufreq_schedutil.c | 77 ++++++++++++++++++++++++++--------------
kernel/sched/deadline.c | 46 ++++++++++++++++++++----
kernel/sched/fair.c | 4 +--
kernel/sched/sched.h | 51 +++++++++++++++++++-------
8 files changed, 149 insertions(+), 59 deletions(-)

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2.11.0