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Date: Mon, 18 Sep 2017 15:54:06 +0200
From: Frederic Weisbecker <fweisbec@...il.com>
To: Ingo Molnar <mingo@...nel.org>
Cc: LKML <linux-kernel@...r.kernel.org>,
Frederic Weisbecker <fweisbec@...il.com>,
Peter Zijlstra <peterz@...radead.org>,
Chris Metcalf <cmetcalf@...lanox.com>,
Thomas Gleixner <tglx@...utronix.de>,
Luiz Capitulino <lcapitulino@...hat.com>,
Christoph Lameter <cl@...ux.com>,
"Paul E . McKenney" <paulmck@...ux.vnet.ibm.com>,
Mike Galbraith <efault@....de>, Rik van Riel <riel@...hat.com>,
Wanpeng Li <kernellwp@...il.com>
Subject: [PATCH 09/12] housekeeping: Handle nohz_full= parameter
We want to centralize the isolation management from the housekeeping
subsystem. Therefore we need to handle the nohz_full= parameter from
there.
Since nohz_full= so far has involved unbound timers, watchdog, RCU
and tilegx NAPI isolation, we keep that default behaviour.
nohz_full= is deemed to be deprecated in the future. We want to control
the isolation features from the isolcpus= parameter.
Signed-off-by: Frederic Weisbecker <fweisbec@...il.com>
Cc: Chris Metcalf <cmetcalf@...lanox.com>
Cc: Rik van Riel <riel@...hat.com>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Mike Galbraith <efault@....de>
Cc: Ingo Molnar <mingo@...nel.org>
Cc: Christoph Lameter <cl@...ux.com>
Cc: Paul E. McKenney <paulmck@...ux.vnet.ibm.com>
Cc: Wanpeng Li <kernellwp@...il.com>
Cc: Luiz Capitulino <lcapitulino@...hat.com>
---
include/linux/housekeeping.h | 1 +
include/linux/tick.h | 2 ++
init/Kconfig | 1 -
kernel/housekeeping.c | 44 +++++++++++++++++++++++++++++++-------------
kernel/time/tick-sched.c | 13 +++----------
5 files changed, 37 insertions(+), 24 deletions(-)
diff --git a/include/linux/housekeeping.h b/include/linux/housekeeping.h
index b1a62544..35fb197 100644
--- a/include/linux/housekeeping.h
+++ b/include/linux/housekeeping.h
@@ -10,6 +10,7 @@ enum hk_flags {
HK_FLAG_RCU = (1 << 1),
HK_FLAG_MISC = (1 << 2),
HK_FLAG_SCHED = (1 << 3),
+ HK_FLAG_TICK = (1 << 4),
};
#ifdef CONFIG_CPU_ISOLATION
diff --git a/include/linux/tick.h b/include/linux/tick.h
index 68afc09..e2a163a 100644
--- a/include/linux/tick.h
+++ b/include/linux/tick.h
@@ -228,6 +228,7 @@ static inline void tick_dep_clear_signal(struct signal_struct *signal,
extern void tick_nohz_full_kick_cpu(int cpu);
extern void __tick_nohz_task_switch(void);
+extern void __init tick_nohz_full_setup(cpumask_var_t cpumask);
#else
static inline bool tick_nohz_full_enabled(void) { return false; }
static inline bool tick_nohz_full_cpu(int cpu) { return false; }
@@ -248,6 +249,7 @@ static inline void tick_dep_clear_signal(struct signal_struct *signal,
static inline void tick_nohz_full_kick_cpu(int cpu) { }
static inline void __tick_nohz_task_switch(void) { }
+static inline void tick_nohz_full_setup(cpumask_var_t cpumask) { }
#endif
static inline void tick_nohz_task_switch(void)
diff --git a/init/Kconfig b/init/Kconfig
index 6f52e6f..f8564df5 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -474,7 +474,6 @@ endmenu # "CPU/Task time and stats accounting"
config CPU_ISOLATION
bool "CPU isolation"
- depends on NO_HZ_FULL
help
Make sure that CPUs running critical tasks are not disturbed by
any source of "noise" such as unbound workqueues, timers, kthreads...
diff --git a/kernel/housekeeping.c b/kernel/housekeeping.c
index 2cf52ee..8fb8d6b 100644
--- a/kernel/housekeeping.c
+++ b/kernel/housekeeping.c
@@ -50,23 +50,41 @@ bool housekeeping_test_cpu(int cpu, enum hk_flags flags)
void __init housekeeping_init(void)
{
- if (!tick_nohz_full_enabled())
+ if (!housekeeping_flags)
return;
- if (!alloc_cpumask_var(&housekeeping_mask, GFP_KERNEL)) {
- WARN(1, "NO_HZ: Can't allocate not-full dynticks cpumask\n");
- cpumask_clear(tick_nohz_full_mask);
- tick_nohz_full_running = false;
- return;
- }
-
- cpumask_andnot(housekeeping_mask,
- cpu_possible_mask, tick_nohz_full_mask);
-
- housekeeping_flags = HK_FLAG_TIMER | HK_FLAG_RCU | HK_FLAG_MISC;
-
static_branch_enable(&housekeeping_overriden);
/* We need at least one CPU to handle housekeeping work */
WARN_ON_ONCE(cpumask_empty(housekeeping_mask));
}
+
+#ifdef CONFIG_NO_HZ_FULL
+static int __init housekeeping_nohz_full_setup(char *str)
+{
+ cpumask_var_t non_housekeeping_mask;
+
+ alloc_bootmem_cpumask_var(&non_housekeeping_mask);
+ if (cpulist_parse(str, non_housekeeping_mask) < 0) {
+ pr_warn("Housekeeping: Incorrect nohz_full cpumask\n");
+ free_bootmem_cpumask_var(non_housekeeping_mask);
+ return 0;
+ }
+
+ alloc_bootmem_cpumask_var(&housekeeping_mask);
+ cpumask_andnot(housekeeping_mask, cpu_possible_mask, non_housekeeping_mask);
+
+ if (cpumask_empty(housekeeping_mask))
+ cpumask_set_cpu(smp_processor_id(), housekeeping_mask);
+
+ housekeeping_flags = HK_FLAG_TICK | HK_FLAG_TIMER |
+ HK_FLAG_RCU | HK_FLAG_MISC;
+
+ tick_nohz_full_setup(non_housekeeping_mask);
+
+ free_bootmem_cpumask_var(non_housekeeping_mask);
+
+ return 1;
+}
+__setup("nohz_full=", housekeeping_nohz_full_setup);
+#endif
diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
index 9d29dee..f09dd43 100644
--- a/kernel/time/tick-sched.c
+++ b/kernel/time/tick-sched.c
@@ -384,20 +384,13 @@ void __tick_nohz_task_switch(void)
local_irq_restore(flags);
}
-/* Parse the boot-time nohz CPU list from the kernel parameters. */
-static int __init tick_nohz_full_setup(char *str)
+/* Get the boot-time nohz CPU list from the kernel parameters. */
+void __init tick_nohz_full_setup(cpumask_var_t cpumask)
{
alloc_bootmem_cpumask_var(&tick_nohz_full_mask);
- if (cpulist_parse(str, tick_nohz_full_mask) < 0) {
- pr_warn("NO_HZ: Incorrect nohz_full cpumask\n");
- free_bootmem_cpumask_var(tick_nohz_full_mask);
- return 1;
- }
+ cpumask_copy(tick_nohz_full_mask, cpumask);
tick_nohz_full_running = true;
-
- return 1;
}
-__setup("nohz_full=", tick_nohz_full_setup);
static int tick_nohz_cpu_down(unsigned int cpu)
{
--
2.7.4
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