mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-08-26 10:49:33 +00:00
sched/deadline: Fix a bug in dl_overflow()
I got a minus(very big) dl_b->total_bw during my deadline tests. # grep dl /proc/sched_debug dl_rq[0]: .dl_nr_running : 0 .dl_bw->bw : 996147 .dl_bw->total_bw : -222297900 Something unusual must have happened. After some digging, I finally noticed that when changing a deadline task to normal(cfs), and changing it back to deadline immediately, after it died, we will got the wrong dl_bw->total_bw. The root cause is in dl_overflow(), it has: if (new_bw == p->dl.dl_bw) return 0; 1) When a deadline task is changed to !deadline task, it will start dl timer in switched_from_dl(), and retain previous deadline parameter till the timer expires. 2) If we change it back to deadline with the same bandwidth parameter before the timer expires, as it keeps the old bandwidth although it is not a deadline task. dl_overflow() simply returns success without updating the right data, and got the wrong dl_bw->total_bw. The solution is simple, if @p is not deadline, don't return. Signed-off-by: Xunlei Pang <xlpang@redhat.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Juri Lelli <juri.lelli@arm.com> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/1460636368-1993-1-git-send-email-xlpang@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
parent
9fd81dd5ce
commit
fec148c000
1 changed files with 2 additions and 1 deletions
|
@ -2378,7 +2378,8 @@ static int dl_overflow(struct task_struct *p, int policy,
|
|||
u64 new_bw = dl_policy(policy) ? to_ratio(period, runtime) : 0;
|
||||
int cpus, err = -1;
|
||||
|
||||
if (new_bw == p->dl.dl_bw)
|
||||
/* !deadline task may carry old deadline bandwidth */
|
||||
if (new_bw == p->dl.dl_bw && task_has_dl_policy(p))
|
||||
return 0;
|
||||
|
||||
/*
|
||||
|
|
Loading…
Reference in a new issue