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Subject[RFC PATCH 0/5] nohz: Fix racy sleeptime stats v2
Date
Hi,

So this is a new iteration with some more changes on top of the latest discussions
we had.

Unfortunately it's not yet a real viable solution. Check out patch 4/5 for details,
I think that's too much overhead. Also it changes enough the semantics to break the
idle sleeptime accounting along the way. This is because moving the accounting to
io_schedule() makes it account _all_ IO sleeptime, even if the CPU is still busy,
not just when it is idle like before. As a result, the idle sleeptime, that relies on
a diff against the io sleeptime, is broken.

Anyway, my hope with this new take is mostly to launch a discussion with a fresher
base and see if we can find better ideas.

Thanks!

git://git.kernel.org/pub/scm/linux/kernel/git/frederic/linux-dynticks.git
sched/iowait

Thanks,
Frederic
---

Frederic Weisbecker (5):
nohz: Convert a few places to use local per cpu accesses
nohz: Only update sleeptime stats locally
timer: Change idle/iowait accounting semantics
sched: Refactor iowait accounting
nohz: Synchronize sleep time stats with seqlock


include/linux/ktime.h | 7 +++
include/linux/sched.h | 1 +
include/linux/tick.h | 11 ++--
kernel/sched/core.c | 68 ++++++++++++++++++---
kernel/sched/cputime.c | 2 +-
kernel/sched/sched.h | 5 +-
kernel/softirq.c | 4 +-
kernel/time/tick-broadcast.c | 6 +-
kernel/time/tick-internal.h | 4 +-
kernel/time/tick-sched.c | 138 ++++++++++++++-----------------------------
kernel/time/timer_list.c | 3 +-
11 files changed, 130 insertions(+), 119 deletions(-)


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