Commit a59f4e07 authored Jan 08, 2013 by Zhu Yanhai Committed by Ingo Molnar Jan 24, 2013

sched: Fix the broken sched_rr_get_interval()



The caller of sched_sliced() should pass se.cfs_rq and se as the
arguments, however in sched_rr_get_interval() we gave it
rq.cfs_rq and se, which made the following computation obviously
wrong.

The change was introduced by commit:

  77034937 sched: fix crash in sys_sched_rr_get_interval()

... 5 years ago, while it had been the correct 'cfs_rq_of' before
the commit. The change seems to be irrelevant to the commit
msg, which was to return a 0 timeslice for tasks that are on an
idle runqueue. So I believe that was just a plain typo.

Signed-off-by: Zhu Yanhai <gaoyang.zyh@taobao.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Paul Turner <pjt@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/1357621012-15039-1-git-send-email-gaoyang.zyh@taobao.com


[ Since this is an ABI and an old bug, we'll test this via a
  slow upstream route, to hopefully discover any app breakage. ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>

parent ff7532ca

kernel/sched/fair.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -6101,7 +6101,7 @@ static unsigned int get_rr_interval_fair(struct rq rq, struct task_struct task
		* idle runqueue:
		*/
		if (rq->cfs.load.weight)
		rr_interval = NS_TO_JIFFIES(sched_slice(&rq->cfs, se));
		rr_interval = NS_TO_JIFFIES(sched_slice(cfs_rq_of(se), se));

		return rr_interval;
		}

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