block: readd plug trace event

This was removed with the queue plug state. But we can easily readd
by checking if this is the first request going to this queue. It's
good information to have when tracing to see how effective the
plugging is.

Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
This commit is contained in:
Jens Axboe 2011-04-12 10:28:28 +02:00
parent f75664570d
commit dc6d36c971

View File

@ -1311,7 +1311,15 @@ get_rq:
plug = current->plug;
if (plug) {
if (!plug->should_sort && !list_empty(&plug->list)) {
/*
* If this is the first request added after a plug, fire
* of a plug trace. If others have been added before, check
* if we have multiple devices in this plug. If so, make a
* note to sort the list before dispatch.
*/
if (list_empty(&plug->list))
trace_block_plug(q);
else if (!plug->should_sort) {
struct request *__rq;
__rq = list_entry_rq(plug->list.prev);