From 8cb9764fc88b41db11f251e8b2a0d006578b7eb4 Mon Sep 17 00:00:00 2001 From: Chris Metcalf <cmetcalf@ezchip.com> Date: Wed, 6 May 2015 18:04:26 +0200 Subject: [PATCH] nohz: Set isolcpus when nohz_full is set nohz_full is only useful with isolcpus are also set, since otherwise the scheduler has to run periodically to try to determine whether to steal work from other cores. Accordingly, when booting with nohz_full=xxx on the command line, we should act as if isolcpus=xxx was also set, and set (or extend) the isolcpus set to include the nohz_full cpus. Signed-off-by: Chris Metcalf <cmetcalf@ezchip.com> Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Acked-by: Rik van Riel <riel@redhat.com> Acked-by: Mike Galbraith <umgwanakikbuti@gmail.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Borislav Petkov <bp@alien8.de> Cc: Dave Jones <davej@redhat.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/1430928266-24888-5-git-send-email-fweisbec@gmail.com Signed-off-by: Ingo Molnar <mingo@kernel.org> --- kernel/sched/core.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 54f032cea040..b8f48763579b 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -7036,6 +7036,9 @@ void __init sched_init_smp(void) alloc_cpumask_var(&non_isolated_cpus, GFP_KERNEL); alloc_cpumask_var(&fallback_doms, GFP_KERNEL); + /* nohz_full won't take effect without isolating the cpus. */ + tick_nohz_full_add_cpus_to(cpu_isolated_map); + sched_init_numa(); /* -- 2.50.1