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

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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>
This commit is contained in:
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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9
include/linux/blktrace_api.h
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@ -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;