ring-buffer: speed up buffer resets by avoiding synchronize_rcu for each CPU

[linux-2.6-microblaze.git] / kernel / trace / ring_buffer.c

diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index 802bb38..ed19413 100644 (file)
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -270,6 +270,9 @@ EXPORT_SYMBOL_GPL(ring_buffer_event_data);
 #define for_each_buffer_cpu(buffer, cpu)               \
        for_each_cpu(cpu, buffer->cpumask)
 
+#define for_each_online_buffer_cpu(buffer, cpu)                \
+       for_each_cpu_and(cpu, buffer->cpumask, cpu_online_mask)
+
 #define TS_SHIFT       27
 #define TS_MASK                ((1ULL << TS_SHIFT) - 1)
 #define TS_DELTA_TEST  (~TS_MASK)
@@ -4790,6 +4793,26 @@ rb_reset_cpu(struct ring_buffer_per_cpu *cpu_buffer)
        rb_head_page_activate(cpu_buffer);
 }
 
+/* Must have disabled the cpu buffer then done a synchronize_rcu */
+static void reset_disabled_cpu_buffer(struct ring_buffer_per_cpu *cpu_buffer)
+{
+       unsigned long flags;
+
+       raw_spin_lock_irqsave(&cpu_buffer->reader_lock, flags);
+
+       if (RB_WARN_ON(cpu_buffer, local_read(&cpu_buffer->committing)))
+               goto out;
+
+       arch_spin_lock(&cpu_buffer->lock);
+
+       rb_reset_cpu(cpu_buffer);
+
+       arch_spin_unlock(&cpu_buffer->lock);
+
+ out:
+       raw_spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags);
+}
+
 /**
  * ring_buffer_reset_cpu - reset a ring buffer per CPU buffer
  * @buffer: The ring buffer to reset a per cpu buffer of
@@ -4798,7 +4821,6 @@ rb_reset_cpu(struct ring_buffer_per_cpu *cpu_buffer)
 void ring_buffer_reset_cpu(struct trace_buffer *buffer, int cpu)
 {
        struct ring_buffer_per_cpu *cpu_buffer = buffer->buffers[cpu];
-       unsigned long flags;
 
        if (!cpumask_test_cpu(cpu, buffer->cpumask))
                return;
@@ -4809,24 +4831,42 @@ void ring_buffer_reset_cpu(struct trace_buffer *buffer, int cpu)
        /* Make sure all commits have finished */
        synchronize_rcu();
 
-       raw_spin_lock_irqsave(&cpu_buffer->reader_lock, flags);
+       reset_disabled_cpu_buffer(cpu_buffer);
 
-       if (RB_WARN_ON(cpu_buffer, local_read(&cpu_buffer->committing)))
-               goto out;
+       atomic_dec(&cpu_buffer->record_disabled);
+       atomic_dec(&cpu_buffer->resize_disabled);
+}
+EXPORT_SYMBOL_GPL(ring_buffer_reset_cpu);
 
-       arch_spin_lock(&cpu_buffer->lock);
+/**
+ * ring_buffer_reset_cpu - reset a ring buffer per CPU buffer
+ * @buffer: The ring buffer to reset a per cpu buffer of
+ * @cpu: The CPU buffer to be reset
+ */
+void ring_buffer_reset_online_cpus(struct trace_buffer *buffer)
+{
+       struct ring_buffer_per_cpu *cpu_buffer;
+       int cpu;
 
-       rb_reset_cpu(cpu_buffer);
+       for_each_online_buffer_cpu(buffer, cpu) {
+               cpu_buffer = buffer->buffers[cpu];
 
-       arch_spin_unlock(&cpu_buffer->lock);
+               atomic_inc(&cpu_buffer->resize_disabled);
+               atomic_inc(&cpu_buffer->record_disabled);
+       }
 
- out:
-       raw_spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags);
+       /* Make sure all commits have finished */
+       synchronize_rcu();
 
-       atomic_dec(&cpu_buffer->record_disabled);
-       atomic_dec(&cpu_buffer->resize_disabled);
+       for_each_online_buffer_cpu(buffer, cpu) {
+               cpu_buffer = buffer->buffers[cpu];
+
+               reset_disabled_cpu_buffer(cpu_buffer);
+
+               atomic_dec(&cpu_buffer->record_disabled);
+               atomic_dec(&cpu_buffer->resize_disabled);
+       }
 }
-EXPORT_SYMBOL_GPL(ring_buffer_reset_cpu);
 
 /**
  * ring_buffer_reset - reset a ring buffer
@@ -4834,10 +4874,27 @@ EXPORT_SYMBOL_GPL(ring_buffer_reset_cpu);
  */
 void ring_buffer_reset(struct trace_buffer *buffer)
 {
+       struct ring_buffer_per_cpu *cpu_buffer;
        int cpu;
 
-       for_each_buffer_cpu(buffer, cpu)
-               ring_buffer_reset_cpu(buffer, cpu);
+       for_each_buffer_cpu(buffer, cpu) {
+               cpu_buffer = buffer->buffers[cpu];
+
+               atomic_inc(&cpu_buffer->resize_disabled);
+               atomic_inc(&cpu_buffer->record_disabled);
+       }
+
+       /* Make sure all commits have finished */
+       synchronize_rcu();
+
+       for_each_buffer_cpu(buffer, cpu) {
+               cpu_buffer = buffer->buffers[cpu];
+
+               reset_disabled_cpu_buffer(cpu_buffer);
+
+               atomic_dec(&cpu_buffer->record_disabled);
+               atomic_dec(&cpu_buffer->resize_disabled);
+       }
 }
 EXPORT_SYMBOL_GPL(ring_buffer_reset);