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

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Date:	Thu, 12 Nov 2015 15:59:32 +0900
From:	Byungchul Park <byungchul.park@....com>
To:	mingo@...nel.org, peterz@...radead.org
Cc:	linux-kernel@...r.kernel.org, efault@....de, tglx@...utronix.de,
	fweisbec@...il.com
Subject: Re: [PATCH v5 0/2] sched: consider missed ticks when updating cpu
 load

On Wed, Nov 11, 2015 at 06:38:10PM +0900, Byungchul Park wrote:
> On Tue, Nov 10, 2015 at 09:36:00AM +0900, byungchul.park@....com wrote:
> > From: Byungchul Park <byungchul.park@....com>
> > 
> > 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
                                                    ^^^
						    last_load_update_tick
> 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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