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| author | Wanpeng Li <wanpeng.li@hotmail.com> | 2016-05-04 14:45:34 +0800 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2016-05-12 09:55:32 +0200 |
| commit | 444969223c81c7d0a95136b7b4cfdcfbc96ac5bd (patch) | |
| tree | c5dceeb9ffe40ee14383c7122378a4e217e21218 /kernel/sched | |
| parent | 2f950354e6d535b892f133d20bd6a8b09430424c (diff) | |
| download | linux-stable-444969223c81c7d0a95136b7b4cfdcfbc96ac5bd.tar.gz linux-stable-444969223c81c7d0a95136b7b4cfdcfbc96ac5bd.tar.bz2 linux-stable-444969223c81c7d0a95136b7b4cfdcfbc96ac5bd.zip | |
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>
Diffstat (limited to 'kernel/sched')
| -rw-r--r-- | kernel/sched/core.c | 5 |
1 files changed, 4 insertions, 1 deletions
diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 636c4b9cac38..6f6962a356b4 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; } |