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authorDmitry Monakhov <dmonakhov@gmail.com>2019-11-01 13:11:10 +0000
committerJens Axboe <axboe@kernel.dk>2019-11-20 16:10:29 -0700
commit40d47c155e8ae9bcb3f2d0d01cf14d903c664726 (patch)
tree80e724192c2ecdb7b0f7199ecadc452fa17d48c8 /block
parentc6da429ea988de8f9330405fc405ee32479b5bd5 (diff)
downloadlinux-40d47c155e8ae9bcb3f2d0d01cf14d903c664726.tar.bz2
block,bfq: Skip tracing hooks if possible
In most cases blk_tracing is not active, but bfq_log_bfqq macro generate pid_str unconditionally, which result in significant overhead. ## Test modprobe null_blk echo bfq > /sys/block/nullb0/queue/scheduler fio --name=t --ioengine=libaio --direct=1 --filename=/dev/nullb0 \ --runtime=30 --time_based=1 --rw=write --iodepth=128 --bs=4k # Results | | baseline | w/ patch | gain | | iops | 113.19K | 126.42K | +11% | Acked-by: Paolo Valente <paolo.valente@linaro.org> Signed-off-by: Dmitry Monakhov <dmonakhov@gmail.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'block')
-rw-r--r--block/bfq-iosched.h4
1 files changed, 4 insertions, 0 deletions
diff --git a/block/bfq-iosched.h b/block/bfq-iosched.h
index 9c82c1f35716..8526f20c53bc 100644
--- a/block/bfq-iosched.h
+++ b/block/bfq-iosched.h
@@ -1068,6 +1068,8 @@ struct bfq_group *bfqq_group(struct bfq_queue *bfqq);
#define bfq_log_bfqq(bfqd, bfqq, fmt, args...) do { \
char pid_str[MAX_PID_STR_LENGTH]; \
+ if (likely(!blk_trace_note_message_enabled((bfqd)->queue))) \
+ break; \
bfq_pid_to_str((bfqq)->pid, pid_str, MAX_PID_STR_LENGTH); \
blk_add_cgroup_trace_msg((bfqd)->queue, \
bfqg_to_blkg(bfqq_group(bfqq))->blkcg, \
@@ -1084,6 +1086,8 @@ struct bfq_group *bfqq_group(struct bfq_queue *bfqq);
#define bfq_log_bfqq(bfqd, bfqq, fmt, args...) do { \
char pid_str[MAX_PID_STR_LENGTH]; \
+ if (likely(!blk_trace_note_message_enabled((bfqd)->queue))) \
+ break; \
bfq_pid_to_str((bfqq)->pid, pid_str, MAX_PID_STR_LENGTH); \
blk_add_trace_msg((bfqd)->queue, "bfq%s%c " fmt, pid_str, \
bfq_bfqq_sync((bfqq)) ? 'S' : 'A', \