sched/isolation: Isolate workqueues when "nohz_full=" is set

As we prepare for offloading the residual 1hz scheduler ticks to
workqueue, let's affine those to housekeepers so that they don't
interrupt the CPUs that don't want to be disturbed.

Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Chris Metcalf <cmetcalf@mellanox.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Luiz Capitulino <lcapitulino@redhat.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Wanpeng Li <kernellwp@gmail.com>
Link: http://lkml.kernel.org/r/1519186649-3242-5-git-send-email-frederic@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>

diff --git a/include/linux/sched/isolation.h b/include/linux/sched/isolation.h
index d849431c8060a17c49ac247745ae1afd5f88f3f2..4a6582c27dea7bb3f15338b97b67869a9b4b05d0 100644 (file)
--- a/include/linux/sched/isolation.h
+++ b/include/linux/sched/isolation.h
@@ -12,6 +12,7 @@ enum hk_flags {
        HK_FLAG_SCHED           = (1 << 3),
        HK_FLAG_TICK            = (1 << 4),
        HK_FLAG_DOMAIN          = (1 << 5),
+       HK_FLAG_WQ              = (1 << 6),
 };
 
 #ifdef CONFIG_CPU_ISOLATION

diff --git a/kernel/sched/isolation.c b/kernel/sched/isolation.c
index b71b436f59f2734a8a92e54c18f806bd2798439d..a2500c459617db40ae4149155c803cb46d29bb3b 100644 (file)
--- a/kernel/sched/isolation.c
+++ b/kernel/sched/isolation.c
@@ -3,6 +3,7 @@
  *  any CPU: unbound workqueues, timers, kthreads and any offloadable work.
  *
  * Copyright (C) 2017 Red Hat, Inc., Frederic Weisbecker
+ * Copyright (C) 2017-2018 SUSE, Frederic Weisbecker
  *
  */
 
@@ -119,7 +120,7 @@ static int __init housekeeping_nohz_full_setup(char *str)
 {
        unsigned int flags;
 
-       flags = HK_FLAG_TICK | HK_FLAG_TIMER | HK_FLAG_RCU | HK_FLAG_MISC;
+       flags = HK_FLAG_TICK | HK_FLAG_WQ | HK_FLAG_TIMER | HK_FLAG_RCU | HK_FLAG_MISC;
 
        return housekeeping_setup(str, flags);
 }

diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index 017044c2623373455274a1d642cecc7e3c4811aa..593dbe74917473baad53326f07b6ce301f26264a 100644 (file)
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -5565,12 +5565,13 @@ static void __init wq_numa_init(void)
 int __init workqueue_init_early(void)
 {
        int std_nice[NR_STD_WORKER_POOLS] = { 0, HIGHPRI_NICE_LEVEL };
+       int hk_flags = HK_FLAG_DOMAIN | HK_FLAG_WQ;
        int i, cpu;
 
        WARN_ON(__alignof__(struct pool_workqueue) < __alignof__(long long));
 
        BUG_ON(!alloc_cpumask_var(&wq_unbound_cpumask, GFP_KERNEL));
-       cpumask_copy(wq_unbound_cpumask, housekeeping_cpumask(HK_FLAG_DOMAIN));
+       cpumask_copy(wq_unbound_cpumask, housekeeping_cpumask(hk_flags));
 
        pwq_cache = KMEM_CACHE(pool_workqueue, SLAB_PANIC);