if trace isn't enabled, parsing cgroup path just wastes cpu
Signed-off-by: Shaohua Li <shli@xxxxxx>
---
block/blk-throttle.c | 5 ++---
include/linux/blktrace_api.h | 9 +++++++++
2 files changed, 11 insertions(+), 3 deletions(-)
diff --git a/block/blk-throttle.c b/block/blk-throttle.c
index 2149a1d..47a3e54 100644
--- a/block/blk-throttle.c
+++ b/block/blk-throttle.c
@@ -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]; \
\
diff --git a/include/linux/blktrace_api.h b/include/linux/blktrace_api.h
index afc1343..0f3172b 100644
--- a/include/linux/blktrace_api.h
+++ b/include/linux/blktrace_api.h
@@ -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;
--
2.8.0.rc2
--
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