Messages in this thread | | | From | Jeff Moyer <> | Subject | Re: [PATCH 3/3] blk-throttle: don't parse cgroup path if trace isn't enabled | Date | Tue, 10 May 2016 11:52:15 -0400 |
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Shaohua Li <shli@fb.com> writes:
> if trace isn't enabled, parsing cgroup path just wastes cpu > > Signed-off-by: Shaohua Li <shli@fb.com> > --- > 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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