Re: [PATCH v5 0/2] sched: consider missed ticks when updating cpu load

From: Byungchul Park
Date: Wed Nov 11 2015 - 04:38:25 EST


On Tue, Nov 10, 2015 at 09:36:00AM +0900, byungchul.park@xxxxxxx wrote:
> From: Byungchul Park <byungchul.park@xxxxxxx>
>
> change from v4 to v5
> - fix comments and commit message
> - take new_load into account in update_cpu_load_nohz() and __update_cpu_load()
> because it's non-zero in NOHZ_FULL
>
> change from v3 to v4
> - focus the problem on full NOHZ
>
> change from v2 to v3
> - add a patch which make __update_cpu_load() handle active tickless
>
> change from v1 to v2
> - add some additional commit message (logic is same exactly)
>
> additionally i tried to use the return value of hrtimer_forward() instead of
> jiffies to get pending tick for updating cpu load. it's easy for
> update_cpu_load_nohz() to do that. but for update_idle_cpu_load(), i need
> more time to think about how to implement it nicely.

Actually because of update_idle_load() which is used when doing nohz
load balancing while the cpu has been still tick-stopped, this looks
not be able to be implemented without any kind of last_update_xxx
variable. What do you think about it, Peter?

>
> and i will try to fix other stuffs caused by full NOHZ later with another
> patch. i decided to send this patch at first because "cpu load update" is a
> standalone problem which is not coupled with other stuffs.
>
> Byungchul Park (2):
> sched: make __update_cpu_load() handle NOHZ_FULL tickless
> sched: make update_cpu_load_nohz() consider missed ticks in NOHZ_FULL
>
> include/linux/sched.h | 4 ++--
> kernel/sched/fair.c | 57 +++++++++++++++++++++++++++++++++++++---------
> kernel/time/tick-sched.c | 8 +++----
> 3 files changed, 52 insertions(+), 17 deletions(-)
>
> --
> 1.7.9.5
>
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