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authorPeter Zijlstra <a.p.zijlstra@chello.nl>2009-06-02 16:46:57 +0200
committerIngo Molnar <mingo@elte.hu>2009-06-02 21:45:32 +0200
commit08247e31ca79b8f02cce47b7e8120797a8726606 (patch)
tree1094dc286ba5033904d07d256f7d739abb4d421d /kernel
parent8e3747c13c39246c7e46def7cf495d9d21d4c5f9 (diff)
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>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/perf_counter.c41
1 files changed, 41 insertions, 0 deletions
diff --git a/kernel/perf_counter.c b/kernel/perf_counter.c
index 3f11a2bc6c7..abe2f3b6c42 100644
--- a/kernel/perf_counter.c
+++ b/kernel/perf_counter.c
@@ -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;
}