trace: Add a new readonly entry to report total buffer size

The current file "buffer_size_kb" reports the size of per-cpu buffer and
not the overall memory allocated which could be misleading. A new file
"buffer_total_size_kb" adds up all the enabled CPU buffer sizes and
reports it. This is only a readonly entry.

Signed-off-by: Vaibhav Nagarnaik <vnagarnaik@google.com>
Cc: Michael Rubin <mrubin@google.com>
Cc: David Sharp <dhsharp@google.com>
Link: http://lkml.kernel.org/r/1313531179-9323-2-git-send-email-vnagarnaik@google.com
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

1 files changed, 33 insertions, 0 deletions

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index e5df02c69b1d..01176788c387 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -3569,6 +3569,30 @@ tracing_entries_write(struct file *filp, const char __user *ubuf,
 }
 
 static ssize_t
+tracing_total_entries_read(struct file *filp, char __user *ubuf,
+                                size_t cnt, loff_t *ppos)
+{
+        struct trace_array *tr = filp->private_data;
+        char buf[64];
+        int r, cpu;
+        unsigned long size = 0, expanded_size = 0;
+
+        mutex_lock(&trace_types_lock);
+        for_each_tracing_cpu(cpu) {
+                size += tr->entries >> 10;
+                if (!ring_buffer_expanded)
+                        expanded_size += trace_buf_size >> 10;
+        }
+        if (ring_buffer_expanded)
+                r = sprintf(buf, "%lu\n", size);
+        else
+                r = sprintf(buf, "%lu (expanded: %lu)\n", size, expanded_size);
+        mutex_unlock(&trace_types_lock);
+
+        return simple_read_from_buffer(ubuf, cnt, ppos, buf, r);
+}
+
+static ssize_t
 tracing_free_buffer_write(struct file *filp, const char __user *ubuf,
                           size_t cnt, loff_t *ppos)
 {
@@ -3739,6 +3763,12 @@ static const struct file_operations tracing_entries_fops = {
         .llseek         = generic_file_llseek,
 };
 
+static const struct file_operations tracing_total_entries_fops = {
+        .open           = tracing_open_generic,
+        .read           = tracing_total_entries_read,
+        .llseek         = generic_file_llseek,
+};
+
 static const struct file_operations tracing_free_buffer_fops = {
         .write          = tracing_free_buffer_write,
         .release        = tracing_free_buffer_release,
@@ -4450,6 +4480,9 @@ static __init int tracer_init_debugfs(void)
         trace_create_file("buffer_size_kb", 0644, d_tracer,
                         &global_trace, &tracing_entries_fops);
 
+        trace_create_file("buffer_total_size_kb", 0444, d_tracer,
+                        &global_trace, &tracing_total_entries_fops);
+
         trace_create_file("free_buffer", 0644, d_tracer,
                         &global_trace, &tracing_free_buffer_fops);