Shaohua Li <shli@xxxxxx> writes:
> 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.
You've only addressed the second part of the TODO, please don't remove
the first part.
> */
> #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;
Do we want to return !!(bt->act_mask & BLK_TC_NOTIFY)?
-Jeff
> +}
> +
> 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;
--
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