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authorAshok Raj <ashok.raj@intel.com>2005-10-31 01:59:54 +0300
committerLinus Torvalds <torvalds@g5.osdl.org>2005-10-31 04:37:14 +0300
commitc32b6b8e524d2c337767d312814484d9289550cf (patch)
tree02e634b0b48db6eccc8774369366daa1893921ea /drivers/cpufreq/cpufreq_stats.c
parentd434fca737bee0862625c2377b987a7713b6b487 (diff)
downloadlinux-c32b6b8e524d2c337767d312814484d9289550cf.tar.xz
[PATCH] create and destroy cpufreq sysfs entries based on cpu notifiers
cpufreq entries in sysfs should only be populated when CPU is online state. When we either boot with maxcpus=x and then boot the other cpus by echoing to sysfs online file, these entries should be created and destroyed when CPU_DEAD is notified. Same treatement as cache entries under sysfs. We place the processor in the lowest frequency, so hw managed P-State transitions can still work on the other threads to save power. Primary goal was to just make these directories appear/disapper dynamically. There is one in this patch i had to do, which i really dont like myself but probably best if someone handling the cpufreq infrastructure could give this code right treatment if this is not acceptable. I guess its probably good for the first cut. - Converting lock_cpu_hotplug()/unlock_cpu_hotplug() to disable/enable preempt. The locking was smack in the middle of the notification path, when the hotplug is already holding the lock. I tried another solution to avoid this so avoid taking locks if we know we are from notification path. The solution was getting very ugly and i decided this was probably good for this iteration until someone who understands cpufreq could do a better job than me. (akpm: export cpucontrol to GPL modules: drivers/cpufreq/cpufreq_stats.c now does lock_cpu_hotplug()) Signed-off-by: Ashok Raj <ashok.raj@intel.com> Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com> Cc: Dave Jones <davej@codemonkey.org.uk> Cc: Zwane Mwaikambo <zwane@holomorphy.com> Cc: Greg KH <greg@kroah.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'drivers/cpufreq/cpufreq_stats.c')
-rw-r--r--drivers/cpufreq/cpufreq_stats.c42
1 files changed, 38 insertions, 4 deletions
diff --git a/drivers/cpufreq/cpufreq_stats.c b/drivers/cpufreq/cpufreq_stats.c
index 741b6b191e6a..3597f25d5efa 100644
--- a/drivers/cpufreq/cpufreq_stats.c
+++ b/drivers/cpufreq/cpufreq_stats.c
@@ -19,6 +19,7 @@
#include <linux/percpu.h>
#include <linux/kobject.h>
#include <linux/spinlock.h>
+#include <linux/notifier.h>
#include <asm/cputime.h>
static spinlock_t cpufreq_stats_lock;
@@ -298,6 +299,27 @@ cpufreq_stat_notifier_trans (struct notifier_block *nb, unsigned long val,
return 0;
}
+static int __cpuinit cpufreq_stat_cpu_callback(struct notifier_block *nfb,
+ unsigned long action, void *hcpu)
+{
+ unsigned int cpu = (unsigned long)hcpu;
+
+ switch (action) {
+ case CPU_ONLINE:
+ cpufreq_update_policy(cpu);
+ break;
+ case CPU_DEAD:
+ cpufreq_stats_free_table(cpu);
+ break;
+ }
+ return NOTIFY_OK;
+}
+
+static struct notifier_block cpufreq_stat_cpu_notifier =
+{
+ .notifier_call = cpufreq_stat_cpu_callback,
+};
+
static struct notifier_block notifier_policy_block = {
.notifier_call = cpufreq_stat_notifier_policy
};
@@ -311,6 +333,7 @@ __init cpufreq_stats_init(void)
{
int ret;
unsigned int cpu;
+
spin_lock_init(&cpufreq_stats_lock);
if ((ret = cpufreq_register_notifier(&notifier_policy_block,
CPUFREQ_POLICY_NOTIFIER)))
@@ -323,20 +346,31 @@ __init cpufreq_stats_init(void)
return ret;
}
- for_each_cpu(cpu)
- cpufreq_update_policy(cpu);
+ register_cpu_notifier(&cpufreq_stat_cpu_notifier);
+ lock_cpu_hotplug();
+ for_each_online_cpu(cpu) {
+ cpufreq_stat_cpu_callback(&cpufreq_stat_cpu_notifier, CPU_ONLINE,
+ (void *)(long)cpu);
+ }
+ unlock_cpu_hotplug();
return 0;
}
static void
__exit cpufreq_stats_exit(void)
{
unsigned int cpu;
+
cpufreq_unregister_notifier(&notifier_policy_block,
CPUFREQ_POLICY_NOTIFIER);
cpufreq_unregister_notifier(&notifier_trans_block,
CPUFREQ_TRANSITION_NOTIFIER);
- for_each_cpu(cpu)
- cpufreq_stats_free_table(cpu);
+ unregister_cpu_notifier(&cpufreq_stat_cpu_notifier);
+ lock_cpu_hotplug();
+ for_each_online_cpu(cpu) {
+ cpufreq_stat_cpu_callback(&cpufreq_stat_cpu_notifier, CPU_DEAD,
+ (void *)(long)cpu);
+ }
+ unlock_cpu_hotplug();
}
MODULE_AUTHOR ("Zou Nan hai <nanhai.zou@intel.com>");