linux-kernel - [PATCH v2 0/3] sched/deadline: Fix double accounting in push_dl

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Message-Id: <20190802145945.18702-1-dietmar.eggemann@arm.com>
Date:   Fri,  2 Aug 2019 15:59:42 +0100
From:   Dietmar Eggemann <dietmar.eggemann@....com>
To:     Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...nel.org>,
        Juri Lelli <juri.lelli@...hat.com>
Cc:     Luca Abeni <luca.abeni@...tannapisa.it>,
        Daniel Bristot de Oliveira <bristot@...hat.com>,
        Valentin Schneider <valentin.schneider@....com>,
        Qais Yousef <qais.yousef@....com>, linux-kernel@...r.kernel.org
Subject: [PATCH v2 0/3] sched/deadline: Fix double accounting in push_dl_task() & some cleanups

While running a simple DL workload (1 DL (12000/100000/100000) task
per CPU) on Arm64 & x86 systems I noticed that some of the
SCHED_WARN_ON() in the rq/running bandwidth (bw) functions trigger.
Patch 1/3 contains a proposal to fix this.

Patch 2-3/3 contain smaller cleanups I discovered while
debugging the actual issue.

Changes v1->v2:
   - Remove rq/running bw accounting in pull_dl_task() as well [1/3]
   - Remove v1's "sched/deadline: Remove unused int flags from
     __dequeue_task_dl()"
   - Change return to BUG_ON() in dequeue in !on_dl_rq case [3/3]
   - Remove v1's "sched/deadline: Use return value of SCHED_WARN_ON()
     in bw accounting"

Dietmar Eggemann (3):
  sched/deadline: Fix double accounting of rq/running bw in push & pull
  sched/deadline: Use __sub_running_bw() throughout
    dl_change_utilization()
  sched/deadline: Cleanup on_dl_rq() handling

 kernel/sched/deadline.c | 21 ++++++---------------
 1 file changed, 6 insertions(+), 15 deletions(-)

-- 
2.17.1