aboutsummaryrefslogtreecommitdiff
diff options
context:
space:
mode:
authorSteven Rostedt <srostedt@redhat.com>2009-05-01 19:40:05 -0400
committerSteven Rostedt <rostedt@goodmis.org>2009-05-05 16:58:24 -0400
commitafbab76a62b69ea6197e19727d4b8a8aef8deb25 (patch)
treecfde06582fb3dbb7f8c00c7d1a8a57b0b0e9d0d1
parent778c55d44eb4f5f658915ed631d68ed9d1ac3ad1 (diff)
downloadlinux-afbab76a62b69ea6197e19727d4b8a8aef8deb25.tar.gz
ring-buffer: have read page swap increment counter with page entries
In the swap page ring buffer code that is used by the ftrace splice code, we scan the page to increment the counter of entries read. With the number of entries already in the page we simply need to add it. [ Impact: speed up reading page from ring buffer ] Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
-rw-r--r--kernel/trace/ring_buffer.c28
1 files changed, 3 insertions, 25 deletions
diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index 342eacc4baa8..9e42a742a3f9 100644
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -2785,28 +2785,6 @@ out:
}
EXPORT_SYMBOL_GPL(ring_buffer_swap_cpu);
-static void rb_remove_entries(struct ring_buffer_per_cpu *cpu_buffer,
- struct buffer_data_page *bpage,
- unsigned int offset)
-{
- struct ring_buffer_event *event;
- unsigned long head;
-
- __raw_spin_lock(&cpu_buffer->lock);
- for (head = offset; head < local_read(&bpage->commit);
- head += rb_event_length(event)) {
-
- event = __rb_data_page_index(bpage, head);
- if (RB_WARN_ON(cpu_buffer, rb_null_event(event)))
- return;
- /* Only count data entries */
- if (event->type_len > RINGBUF_TYPE_DATA_TYPE_LEN_MAX)
- continue;
- cpu_buffer->read++;
- }
- __raw_spin_unlock(&cpu_buffer->lock);
-}
-
/**
* ring_buffer_alloc_read_page - allocate a page to read from buffer
* @buffer: the buffer to allocate for.
@@ -2977,6 +2955,9 @@ int ring_buffer_read_page(struct ring_buffer *buffer,
/* we copied everything to the beginning */
read = 0;
} else {
+ /* update the entry counter */
+ cpu_buffer->read += local_read(&reader->entries);
+
/* swap the pages */
rb_init_page(bpage);
bpage = reader->page;
@@ -2985,9 +2966,6 @@ int ring_buffer_read_page(struct ring_buffer *buffer,
local_set(&reader->entries, 0);
reader->read = 0;
*data_page = bpage;
-
- /* update the entry counter */
- rb_remove_entries(cpu_buffer, bpage, read);
}
ret = read;