2 files changed, 82 insertions, 1 deletions

diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index 731201bf4acc..acf6b68dc4a8 100644
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -488,12 +488,14 @@ struct ring_buffer_per_cpu {
         struct buffer_page              *reader_page;
         unsigned long                   lost_events;
         unsigned long                   last_overrun;
+        local_t                         entries_bytes;
         local_t                         commit_overrun;
         local_t                         overrun;
         local_t                         entries;
         local_t                         committing;
         local_t                         commits;
         unsigned long                   read;
+        unsigned long                   read_bytes;
         u64                             write_stamp;
         u64                             read_stamp;
 };
@@ -1708,6 +1710,7 @@ rb_handle_head_page(struct ring_buffer_per_cpu *cpu_buffer,
                  * the counters.
                  */
                 local_add(entries, &cpu_buffer->overrun);
+                local_sub(BUF_PAGE_SIZE, &cpu_buffer->entries_bytes);
 
                 /*
                  * The entries will be zeroed out when we move the
@@ -1863,6 +1866,9 @@ rb_reset_tail(struct ring_buffer_per_cpu *cpu_buffer,
         event = __rb_page_index(tail_page, tail);
         kmemcheck_annotate_bitfield(event, bitfield);
 
+        /* account for padding bytes */
+        local_add(BUF_PAGE_SIZE - tail, &cpu_buffer->entries_bytes);
+
         /*
          * Save the original length to the meta data.
          * This will be used by the reader to add lost event
@@ -2054,6 +2060,9 @@ __rb_reserve_next(struct ring_buffer_per_cpu *cpu_buffer,
         if (!tail)
                 tail_page->page->time_stamp = ts;
 
+        /* account for these added bytes */
+        local_add(length, &cpu_buffer->entries_bytes);
+
         return event;
 }
 
@@ -2076,6 +2085,7 @@ rb_try_to_discard(struct ring_buffer_per_cpu *cpu_buffer,
         if (bpage->page == (void *)addr && rb_page_write(bpage) == old_index) {
                 unsigned long write_mask =
                         local_read(&bpage->write) & ~RB_WRITE_MASK;
+                unsigned long event_length = rb_event_length(event);
                 /*
                  * This is on the tail page. It is possible that
                  * a write could come in and move the tail page
@@ -2085,8 +2095,11 @@ rb_try_to_discard(struct ring_buffer_per_cpu *cpu_buffer,
                 old_index += write_mask;
                 new_index += write_mask;
                 index = local_cmpxchg(&bpage->write, old_index, new_index);
-                if (index == old_index)
+                if (index == old_index) {
+                        /* update counters */
+                        local_sub(event_length, &cpu_buffer->entries_bytes);
                         return 1;
+                }
         }
 
         /* could not discard */
@@ -2661,6 +2674,58 @@ rb_num_of_entries(struct ring_buffer_per_cpu *cpu_buffer)
 }
 
 /**
+ * ring_buffer_oldest_event_ts - get the oldest event timestamp from the buffer
+ * @buffer: The ring buffer
+ * @cpu: The per CPU buffer to read from.
+ */
+unsigned long ring_buffer_oldest_event_ts(struct ring_buffer *buffer, int cpu)
+{
+        unsigned long flags;
+        struct ring_buffer_per_cpu *cpu_buffer;
+        struct buffer_page *bpage;
+        unsigned long ret;
+
+        if (!cpumask_test_cpu(cpu, buffer->cpumask))
+                return 0;
+
+        cpu_buffer = buffer->buffers[cpu];
+        spin_lock_irqsave(&cpu_buffer->reader_lock, flags);
+        /*
+         * if the tail is on reader_page, oldest time stamp is on the reader
+         * page
+         */
+        if (cpu_buffer->tail_page == cpu_buffer->reader_page)
+                bpage = cpu_buffer->reader_page;
+        else
+                bpage = rb_set_head_page(cpu_buffer);
+        ret = bpage->page->time_stamp;
+        spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags);
+
+        return ret;
+}
+EXPORT_SYMBOL_GPL(ring_buffer_oldest_event_ts);
+
+/**
+ * ring_buffer_bytes_cpu - get the number of bytes consumed in a cpu buffer
+ * @buffer: The ring buffer
+ * @cpu: The per CPU buffer to read from.
+ */
+unsigned long ring_buffer_bytes_cpu(struct ring_buffer *buffer, int cpu)
+{
+        struct ring_buffer_per_cpu *cpu_buffer;
+        unsigned long ret;
+
+        if (!cpumask_test_cpu(cpu, buffer->cpumask))
+                return 0;
+
+        cpu_buffer = buffer->buffers[cpu];
+        ret = local_read(&cpu_buffer->entries_bytes) - cpu_buffer->read_bytes;
+
+        return ret;
+}
+EXPORT_SYMBOL_GPL(ring_buffer_bytes_cpu);
+
+/**
  * ring_buffer_entries_cpu - get the number of entries in a cpu buffer
  * @buffer: The ring buffer
  * @cpu: The per CPU buffer to get the entries from.
@@ -3527,11 +3592,13 @@ rb_reset_cpu(struct ring_buffer_per_cpu *cpu_buffer)
         cpu_buffer->reader_page->read = 0;
 
         local_set(&cpu_buffer->commit_overrun, 0);
+        local_set(&cpu_buffer->entries_bytes, 0);
         local_set(&cpu_buffer->overrun, 0);
         local_set(&cpu_buffer->entries, 0);
         local_set(&cpu_buffer->committing, 0);
         local_set(&cpu_buffer->commits, 0);
         cpu_buffer->read = 0;
+        cpu_buffer->read_bytes = 0;
 
         cpu_buffer->write_stamp = 0;
         cpu_buffer->read_stamp = 0;
@@ -3918,6 +3985,7 @@ int ring_buffer_read_page(struct ring_buffer *buffer,
         } else {
                 /* update the entry counter */
                 cpu_buffer->read += rb_page_entries(reader);
+                cpu_buffer->read_bytes += BUF_PAGE_SIZE;
 
                 /* swap the pages */
                 rb_init_page(bpage);
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 01176788c387..b41907000bc6 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -4056,6 +4056,8 @@ tracing_stats_read(struct file *filp, char __user *ubuf,
         struct trace_array *tr = &global_trace;
         struct trace_seq *s;
         unsigned long cnt;
+        unsigned long long t;
+        unsigned long usec_rem;
 
         s = kmalloc(sizeof(*s), GFP_KERNEL);
         if (!s)
@@ -4072,6 +4074,17 @@ tracing_stats_read(struct file *filp, char __user *ubuf,
         cnt = ring_buffer_commit_overrun_cpu(tr->buffer, cpu);
         trace_seq_printf(s, "commit overrun: %ld\n", cnt);
 
+        cnt = ring_buffer_bytes_cpu(tr->buffer, cpu);
+        trace_seq_printf(s, "bytes: %ld\n", cnt);
+
+        t = ns2usecs(ring_buffer_oldest_event_ts(tr->buffer, cpu));
+        usec_rem = do_div(t, USEC_PER_SEC);
+        trace_seq_printf(s, "oldest event ts: %5llu.%06lu\n", t, usec_rem);
+
+        t = ns2usecs(ring_buffer_time_stamp(tr->buffer, cpu));
+        usec_rem = do_div(t, USEC_PER_SEC);
+        trace_seq_printf(s, "now ts: %5llu.%06lu\n", t, usec_rem);
+
         count = simple_read_from_buffer(ubuf, count, ppos, s->buffer, s->len);
 
         kfree(s);