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perf_counter: Add ioctl for changing the sample period/frequency 

Reported-by: Stephane Eranian <eranian@googlemail.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: John Kacur <jkacur@redhat.com>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Peter Zijlstra 2009-06-02 16:46:57 +02:00 committed by Ingo Molnar
parent 8e3747c13c
commit 08247e31ca
2 changed files with 46 additions and 4 deletions
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9
include/linux/perf_counter.h
View File

@ -164,10 +164,11 @@ struct perf_counter_hw_event {
/*
* Ioctls that can be done on a perf counter fd:
*/
#define PERF_COUNTER_IOC_ENABLE _IOW('$', 0, u32)
#define PERF_COUNTER_IOC_DISABLE _IOW('$', 1, u32)
#define PERF_COUNTER_IOC_REFRESH _IOW('$', 2, u32)
#define PERF_COUNTER_IOC_RESET _IOW('$', 3, u32)
#define PERF_COUNTER_IOC_ENABLE _IO ('$', 0)
#define PERF_COUNTER_IOC_DISABLE _IO ('$', 1)
#define PERF_COUNTER_IOC_REFRESH _IO ('$', 2)
#define PERF_COUNTER_IOC_RESET _IO ('$', 3)
#define PERF_COUNTER_IOC_PERIOD _IOW('$', 4, u64)
enum perf_counter_ioc_flags {
PERF_IOC_FLAG_GROUP = 1U << 0,

41
kernel/perf_counter.c
View File

@ -1604,6 +1604,43 @@ static void perf_counter_for_each(struct perf_counter *counter,
mutex_unlock(&counter->child_mutex);
}
static int perf_counter_period(struct perf_counter *counter, u64 __user *arg)
{
struct perf_counter_context *ctx = counter->ctx;
unsigned long size;
int ret = 0;
u64 value;
if (!counter->hw_event.sample_period)
return -EINVAL;
size = copy_from_user(&value, arg, sizeof(value));
if (size != sizeof(value))
return -EFAULT;
if (!value)
return -EINVAL;
spin_lock_irq(&ctx->lock);
if (counter->hw_event.freq) {
if (value > sysctl_perf_counter_limit) {
ret = -EINVAL;
goto unlock;
}
counter->hw_event.sample_freq = value;
} else {
counter->hw_event.sample_period = value;
counter->hw.sample_period = value;
perf_log_period(counter, value);
}
unlock:
spin_unlock_irq(&ctx->lock);
return ret;
}
static long perf_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
struct perf_counter *counter = file->private_data;
@ -1623,6 +1660,10 @@ static long perf_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
case PERF_COUNTER_IOC_REFRESH:
return perf_counter_refresh(counter, arg);
case PERF_COUNTER_IOC_PERIOD:
return perf_counter_period(counter, (u64 __user *)arg);
default:
return -ENOTTY;
}