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SubjectRe: [GIT PULL] isolation: 1Hz residual tick offloading v3
On Thu,  4 Jan 2018 05:25:32 +0100
Frederic Weisbecker <frederic@kernel.org> wrote:

> Ingo,
>
> Please pull the sched/0hz branch that can be found at:
>
> git://git.kernel.org/pub/scm/linux/kernel/git/frederic/linux-dynticks.git
> sched/0hz
>
> HEAD: 9e932b2cc707209febd130978a5eb9f4a943a3f4
>
> --
> Now that scheduler_tick() has become resilient towards the absence of
> ticks, current->sched_class->task_tick() is the last piece that needs
> at least 1Hz tick to keep scheduler stats alive.
>
> This patchset adds a flag to the isolcpus boot option to offload the
> residual 1Hz tick. This way the nohz_full CPUs don't have anymore tick
> (assuming nothing else requires it) as their residual 1Hz tick is
> offloaded to the housekeepers.
>
> For quick testing, say on CPUs 1-7:
>
> "isolcpus=nohz_offload,domain,1-7"

Sorry for being very late to this series, but I've a few comments to
make (one right now and others in individual patches).

Why are extending isolcpus= given that it's a deprecated interface?
Some people have already moved away from isolcpus= now, but with this
new feature they will be forced back to using it.

What about just adding the new functionality to nohz_full=? That is,
no new options, just make the tick go away since this has always been
what nohz_full= was intended to do?

>
> Thanks,
> Frederic
> ---
>
> Frederic Weisbecker (5):
> sched: Rename init_rq_hrtick to hrtick_rq_init
> sched/isolation: Add scheduler tick offloading interface
> nohz: Allow to check if remote CPU tick is stopped
> sched/isolation: Residual 1Hz scheduler tick offload
> sched/isolation: Document "nohz_offload" flag
>
>
> Documentation/admin-guide/kernel-parameters.txt | 7 +-
> include/linux/sched/isolation.h | 3 +-
> include/linux/tick.h | 2 +
> kernel/sched/core.c | 94 +++++++++++++++++++++++--
> kernel/sched/isolation.c | 10 +++
> kernel/sched/sched.h | 2 +
> kernel/time/tick-sched.c | 7 ++
> 7 files changed, 117 insertions(+), 8 deletions(-)
>

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