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realtime: disable timer migration

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It was found during code review that the kernel always try to
migrate timers away from idle CPUs to busy CPUs. Real-time
CPUs running dpdk polling threads for example, are busy so
they are a great candidate to receive timers from idle CPUs
(see get_nohz_timer_target() in the kernel sources).

It is not clear how this problem can affect real-time
applications and KVM-RT. However, for real-time and
high-performance the best thing is for a timer to always
fire in the CPU where it was created.

Resolves: rhbz#1323283

Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
This commit is contained in:
Luiz Capitulino 2016-04-01 13:34:24 -04:00 committed by Jaroslav Škarvada
parent 52f2cc4ad7
commit 32ef5d8db0
1 changed files with 1 additions and 0 deletions
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profiles/realtime/tuned.conf
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@ -18,6 +18,7 @@ kernel.hung_task_timeout_secs = 600
kernel.nmi_watchdog = 0
kernel.sched_rt_runtime_us = 1000000
vm.stat_interval = 10
kernel.timer_migration = 0
[sysfs]
/sys/bus/workqueue/devices/writeback/cpumask = ${not_isolated_cpumask}