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Commit 59fa0224 authored by Shaohua Li's avatar Shaohua Li Committed by Jens Axboe
Browse files

blk-throttle: don't parse cgroup path if trace isn't enabled 



if trace isn't enabled, parsing cgroup path just wastes cpu

Signed-off-by: default avatarShaohua Li <shli@fb.com>
Signed-off-by: default avatarJens Axboe <axboe@fb.com>
parent 8d1547e0

block/blk-throttle.c

+2 −3
Original line number Diff line number Diff line
@@ -211,15 +211,14 @@ static struct throtl_data *sq_to_td(struct throtl_service_queue *sq) 
 *

 * The messages are prefixed with "throtl BLKG_NAME" if @sq belongs to a

 * throtl_grp; otherwise, just "throtl".

 *

 * TODO: this should be made a function and name formatting should happen

 * after testing whether blktrace is enabled.

 */

#define throtl_log(sq, fmt, args...)	do {				\

	struct throtl_grp *__tg = sq_to_tg((sq));			\

	struct throtl_data *__td = sq_to_td((sq));			\

									\

	(void)__td;							\

	if (likely(!blk_trace_note_message_enabled(__td->queue)))	\

		break;							\

	if ((__tg)) {							\

		char __pbuf[128];					\

									\

include/linux/blktrace_api.h

+9 −0
Original line number Diff line number Diff line
@@ -57,6 +57,14 @@ void __trace_note_message(struct blk_trace *, const char *fmt, ...); 
	} while (0)

#define BLK_TN_MAX_MSG		128



static inline bool blk_trace_note_message_enabled(struct request_queue *q)

{

	struct blk_trace *bt = q->blk_trace;

	if (likely(!bt))

		return false;

	return bt->act_mask & BLK_TC_NOTIFY;

}



extern void blk_add_driver_data(struct request_queue *q, struct request *rq,

				void *data, size_t len);

extern int blk_trace_setup(struct request_queue *q, char *name, dev_t dev,
@@ -79,6 +87,7 @@ extern struct attribute_group blk_trace_attr_group; 
# define blk_trace_remove(q)				(-ENOTTY)

# define blk_add_trace_msg(q, fmt, ...)			do { } while (0)

# define blk_trace_remove_sysfs(dev)			do { } while (0)

# define blk_trace_note_message_enabled(q)		(false)

static inline int blk_trace_init_sysfs(struct device *dev)

{

	return 0;