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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: Shaohua Li <shli@fb.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
hifive-unleashed-5.1
Shaohua Li 2016-05-09 17:22:15 -07:00 committed by Jens Axboe
parent 8d1547e08d
commit 59fa0224cf
2 changed files with 11 additions and 3 deletions
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5
block/blk-throttle.c
View File

@ -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]; \
\

9
include/linux/blktrace_api.h
View File

@ -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;