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Message-ID: <20090616053854.30891.16480.stgit@sofia.in.ibm.com>
Date: Tue, 16 Jun 2009 11:08:54 +0530
From: Gautham R Shenoy <ego@...ibm.com>
To: linux-kernel@...r.kernel.org
Cc: Peter Zijlstra <a.p.zijlstra@...llo.nl>,
Balbir Singh <balbir@...ibm.com>,
Rusty Russel <rusty@...tcorp.com.au>,
Paul E McKenney <paulmck@...ibm.com>,
Nathan Lynch <ntl@...ox.com>, Ingo Molnar <mingo@...e.hu>,
Venkatesh Pallipadi <venkatesh.pallipadi@...el.com>,
Andrew Morton <akpm@...ux-foundation.org>,
Vaidyanathan Srinivasan <svaidy@...ux.vnet.ibm.com>,
Dipankar Sarma <dipankar@...ibm.com>,
Shoahua Li <shaohua.li@...ux.com>
Subject: [RFD PATCH 3/4] cpu: Define new functions cpu_down_mask and
cpu_up_mask
Currently cpu-hotplug operation is carried out on a single processor at any
given time. We create two functions which will enable us to offline/online
multiple CPUs in a single go.
These functions are:
int cpu_down_mask(cpumask_var_t cpus_to_offline);
int cpu_up_mask(cpumask_var_t cpus_to_online);
In this patch, these functions serially invoke the _cpu_down() and _cpu_up()
functions for each of the CPUs in the cpumask.
The idea is to make the CPU-hotplug notifiers work on cpumasks so that they
can optimize for hotplugging multiple CPUs.
Signed-off-by: Gautham R Shenoy <ego@...ibm.com>
---
drivers/base/cpu.c | 4 ++
include/linux/cpu.h | 2 +
kernel/cpu.c | 92 +++++++++++++++++++++++++++++++++++++--------------
3 files changed, 73 insertions(+), 25 deletions(-)
diff --git a/drivers/base/cpu.c b/drivers/base/cpu.c
index 7a15e7b..1a382da 100644
--- a/drivers/base/cpu.c
+++ b/drivers/base/cpu.c
@@ -154,6 +154,8 @@ static ssize_t store_cpus_online(struct sysdev_class *dev_class,
cpumask_copy(cpu_debug_online_mask, store_cpus_online_mask);
+ ret = cpu_up_mask(store_cpus_online_mask);
+
out:
free_cpumask_var(store_cpus_online_mask);
if (ret >= 0)
@@ -221,6 +223,8 @@ static ssize_t store_cpus_offline(struct sysdev_class *dev_class,
cpumask_copy(cpu_debug_offline_mask, store_cpus_offline_mask);
+ ret = cpu_down_mask(store_cpus_offline_mask);
+
out:
free_cpumask_var(store_cpus_offline_mask);
if (ret >= 0)
diff --git a/include/linux/cpu.h b/include/linux/cpu.h
index 2643d84..4769ff6 100644
--- a/include/linux/cpu.h
+++ b/include/linux/cpu.h
@@ -68,6 +68,7 @@ static inline void unregister_cpu_notifier(struct notifier_block *nb)
#endif
int cpu_up(unsigned int cpu);
+int cpu_up_mask(const cpumask_var_t cpus_to_online);
void notify_cpu_starting(unsigned int cpu);
extern void cpu_hotplug_init(void);
extern void cpu_maps_update_begin(void);
@@ -112,6 +113,7 @@ extern void put_online_cpus(void);
#define register_hotcpu_notifier(nb) register_cpu_notifier(nb)
#define unregister_hotcpu_notifier(nb) unregister_cpu_notifier(nb)
int cpu_down(unsigned int cpu);
+int cpu_down_mask(const cpumask_var_t cpus_to_offline);
#else /* CONFIG_HOTPLUG_CPU */
diff --git a/kernel/cpu.c b/kernel/cpu.c
index 395b697..2b5d4e0 100644
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -267,9 +267,10 @@ out_release:
return err;
}
-int __ref cpu_down(unsigned int cpu)
+int __ref cpu_down_mask(const cpumask_var_t cpus_to_offline)
{
int err;
+ unsigned int cpu;
err = stop_machine_create();
if (err)
@@ -281,28 +282,48 @@ int __ref cpu_down(unsigned int cpu)
goto out;
}
- set_cpu_active(cpu, false);
+ for_each_cpu(cpu, cpus_to_offline) {
+ set_cpu_active(cpu, false);
- /*
- * Make sure the all cpus did the reschedule and are not
- * using stale version of the cpu_active_mask.
- * This is not strictly necessary becuase stop_machine()
- * that we run down the line already provides the required
- * synchronization. But it's really a side effect and we do not
- * want to depend on the innards of the stop_machine here.
- */
- synchronize_sched();
+ /*
+ * Make sure the all cpus did the reschedule and are not
+ * using stale version of the cpu_active_mask.
+ * This is not strictly necessary becuase stop_machine()
+ * that we run down the line already provides the required
+ * synchronization. But it's really a side effect and we do not
+ * want to depend on the innards of the stop_machine here.
+ */
+ synchronize_sched();
- err = _cpu_down(cpu, 0);
+ err = _cpu_down(cpu, 0);
- if (cpu_online(cpu))
- set_cpu_active(cpu, true);
+ if (cpu_online(cpu))
+ set_cpu_active(cpu, true);
+ }
out:
cpu_maps_update_done();
stop_machine_destroy();
return err;
}
+
+int __ref cpu_down(unsigned int cpu)
+{
+ int err;
+ cpumask_var_t cpus_to_offline;
+
+ if (!alloc_cpumask_var(&cpus_to_offline, GFP_KERNEL))
+ return -ENOMEM;
+
+ cpumask_clear(cpus_to_offline);
+ cpumask_set_cpu(cpu, cpus_to_offline);
+
+ err = cpu_down_mask(cpus_to_offline);
+
+ free_cpumask_var(cpus_to_offline);
+
+ return err;
+}
EXPORT_SYMBOL(cpu_down);
#endif /*CONFIG_HOTPLUG_CPU*/
@@ -347,33 +368,54 @@ out_notify:
return ret;
}
-int __cpuinit cpu_up(unsigned int cpu)
+int __cpuinit cpu_up_mask(const cpumask_var_t cpus_to_online)
{
int err = 0;
- if (!cpu_possible(cpu)) {
- printk(KERN_ERR "can't online cpu %d because it is not "
- "configured as may-hotadd at boot time\n", cpu);
+ unsigned int cpu;
+
+ cpu_maps_update_begin();
+ for_each_cpu(cpu, cpus_to_online) {
+ if (!cpu_possible(cpu)) {
+ printk(KERN_ERR "can't online cpu %d because it is not"
+ " configured as may-hotadd at boot time\n", cpu);
#if defined(CONFIG_IA64) || defined(CONFIG_X86_64)
- printk(KERN_ERR "please check additional_cpus= boot "
- "parameter\n");
+ printk(KERN_ERR "please check additional_cpus= boot "
+ "parameter\n");
#endif
- return -EINVAL;
+ err = -EINVAL;
+ goto out;
+ }
}
- cpu_maps_update_begin();
-
if (cpu_hotplug_disabled) {
err = -EBUSY;
goto out;
}
-
- err = _cpu_up(cpu, 0);
+ for_each_cpu(cpu, cpus_to_online)
+ err = _cpu_up(cpu, 0);
out:
cpu_maps_update_done();
return err;
}
+int __cpuinit cpu_up(unsigned int cpu)
+{
+ int err = 0;
+ cpumask_var_t cpus_to_online;
+
+ if (!alloc_cpumask_var(&cpus_to_online, GFP_KERNEL))
+ return -ENOMEM;
+
+ cpumask_clear(cpus_to_online);
+ cpumask_set_cpu(cpu, cpus_to_online);
+
+ err = cpu_up_mask(cpus_to_online);
+
+ free_cpumask_var(cpus_to_online);
+
+ return err;
+}
#ifdef CONFIG_PM_SLEEP_SMP
static cpumask_var_t frozen_cpus;
--
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