Messages in this thread Patch in this message | | | Date | Thu, 12 May 2016 03:31:04 -0700 | From | tip-bot for Wanpeng Li <> | Subject | [tip:sched/core] sched/nohz: Fix affine unpinned timers mess |
| |
Commit-ID: 444969223c81c7d0a95136b7b4cfdcfbc96ac5bd Gitweb: http://git.kernel.org/tip/444969223c81c7d0a95136b7b4cfdcfbc96ac5bd Author: Wanpeng Li <wanpeng.li@hotmail.com> AuthorDate: Wed, 4 May 2016 14:45:34 +0800 Committer: Ingo Molnar <mingo@kernel.org> CommitDate: Thu, 12 May 2016 09:55:32 +0200
sched/nohz: Fix affine unpinned timers mess
The following commit:
9642d18eee2c ("nohz: Affine unpinned timers to housekeepers")'
intended to affine unpinned timers to housekeepers:
unpinned timers(full dynaticks, idle) => nearest busy housekeepers(otherwise, fallback to any housekeepers) unpinned timers(full dynaticks, busy) => nearest busy housekeepers(otherwise, fallback to any housekeepers) unpinned timers(houserkeepers, idle) => nearest busy housekeepers(otherwise, fallback to itself)
However, the !idle_cpu(i) && is_housekeeping_cpu(cpu) check modified the intention to:
unpinned timers(full dynaticks, idle) => any housekeepers(no mattter cpu topology) unpinned timers(full dynaticks, busy) => any housekeepers(no mattter cpu topology) unpinned timers(housekeepers, idle) => any busy cpus(otherwise, fallback to any housekeepers)
This patch fixes it by checking if there are busy housekeepers nearby, otherwise falls to any housekeepers/itself. After the patch:
unpinned timers(full dynaticks, idle) => nearest busy housekeepers(otherwise, fallback to any housekeepers) unpinned timers(full dynaticks, busy) => nearest busy housekeepers(otherwise, fallback to any housekeepers) unpinned timers(housekeepers, idle) => nearest busy housekeepers(otherwise, fallback to itself)
Signed-off-by: Wanpeng Li <wanpeng.li@hotmail.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> [ Fixed the changelog. ] Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-kernel@vger.kernel.org Fixes: 'commit 9642d18eee2c ("nohz: Affine unpinned timers to housekeepers")' Link: http://lkml.kernel.org/r/1462344334-8303-1-git-send-email-wanpeng.li@hotmail.com Signed-off-by: Ingo Molnar <mingo@kernel.org> --- kernel/sched/core.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 636c4b9..6f6962a 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -533,7 +533,10 @@ int get_nohz_timer_target(void) rcu_read_lock(); for_each_domain(cpu, sd) { for_each_cpu(i, sched_domain_span(sd)) { - if (!idle_cpu(i) && is_housekeeping_cpu(cpu)) { + if (cpu == i) + continue; + + if (!idle_cpu(i) && is_housekeeping_cpu(i)) { cpu = i; goto unlock; }
| |