Re: [PATCH v3 0/5] sync a se with its cfs_rq when att(det)aching it

Byungchul Park
2015-08-19T07:00:24Z

On Wed, Aug 19, 2015 at 03:47:11PM +0900, byungchul.park@lge.com wrote:
> From: Byungchul Park <byungchul.park@lge.com>
>
> hello,
>
> there are 3 problems when att(det)aching a se to(from) its cfs_rq.
>
> problem 1. se's average load is not accounted with new cfs_rq in queued case,
> when a task changes its cgroup.
>
> problem 2. cfs_rq->avg.load_avg becomes larger and larger whenever changing
> cgroup to another. we have to sync se's average load with prev cfs_rq.
>
> problem 3. current code does not sync it with its cfs_rq when switching
> sched class to fair class. if we can always assume that a se has been
> detached from fair class for a long time enough for its average load to
> become useless, at the time attaching it to its fair class cfs_rq, then
> current code is acceptable. but the assumption is not always true.
>
> patch 1/5, does code refactoring for further patches.
> patch 2/5, solves the problem 1.
> patch 3/5, solves the problem 2.
> patch 4/5, solves the problem 3.
> patch 5/5, does code refactoring for better readability.
>
> change from v2 to v1 (logic is not changed at all)

change from v2 to v3 (logic is not changed at all)

i am sorry for typo.

> * fix up my poor english in commit message and comment
> * break down big patches into more patches for being reviewed easily
> * supplement cover letter messages
>
> change from v1 to v2
> * introduce two functions for adjusting vruntime and load when attaching
> and detaching.
> * call the introduced functions instead of switched_from(to)_fair() directly
> in task_move_group_fair().
> * add decaying logic for a se which has detached from a cfs_rq.
>
> thanks,
> byungchul
>
> Byungchul Park (5):
> sched: add two functions adjusting cfs_rq's load when att(det)aching
> a se
> sched: make task_move_group_fair adjust cfs_rq's load in case of
> queued
> sched: sync a se with prev cfs_rq when changing cgroup
> sched: sync a se with its cfs_rq when switching sched class to fair
> class
> sched: add two functions for att(det)aching a task to(from) a cfs_rq
>
> kernel/sched/fair.c | 209 +++++++++++++++++++++++++++------------------------
> 1 file changed, 110 insertions(+), 99 deletions(-)
>
> --
> 1.7.9.5
>
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