From: Hongnan Li <hongnan.li@linux.alibaba.com>
To: linux-block@vger.kernel.org
Cc: axboe@kernel.dk, Hongnan Li <hongnan.li@linux.alibaba.com>
Subject: [PATCH] blk-iolatency:postpone ktime_get() execution until blk_iolatency_enabled() return true
Date: Wed, 1 Jul 2020 14:04:27 +0800 [thread overview]
Message-ID: <1593583467-18945-1-git-send-email-hongnan.li@linux.alibaba.com> (raw)
ktime_to_ns(ktime_get()) which is expensive do not need to be executed if
blk_iolatency_enabled() return false in blkcg_iolatency_done_bio().
Postponing ktime_to_ns(ktime_get()) execution can reduce CPU usage
when blk_iolatency was disabled.
Signed-off-by: Hongnan Li <hongnan.li@linux.alibaba.com>
---
block/blk-iolatency.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/block/blk-iolatency.c b/block/blk-iolatency.c
index c128d50..8c1487e 100644
--- a/block/blk-iolatency.c
+++ b/block/blk-iolatency.c
@@ -591,7 +591,7 @@ static void blkcg_iolatency_done_bio(struct rq_qos *rqos, struct bio *bio)
struct rq_wait *rqw;
struct iolatency_grp *iolat;
u64 window_start;
- u64 now = ktime_to_ns(ktime_get());
+
bool issue_as_root = bio_issue_as_root_blkg(bio);
bool enabled = false;
int inflight = 0;
@@ -608,6 +608,7 @@ static void blkcg_iolatency_done_bio(struct rq_qos *rqos, struct bio *bio)
if (!enabled)
return;
+ u64 now = ktime_to_ns(ktime_get());
while (blkg && blkg->parent) {
iolat = blkg_to_lat(blkg);
if (!iolat) {
--
1.8.3.1
next reply other threads:[~2020-07-01 6:05 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-01 6:04 Hongnan Li [this message]
2020-07-01 7:52 ` [PATCH] blk-iolatency:postpone ktime_get() execution until blk_iolatency_enabled() return true Johannes Thumshirn
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=1593583467-18945-1-git-send-email-hongnan.li@linux.alibaba.com \
--to=hongnan.li@linux.alibaba.com \
--cc=axboe@kernel.dk \
--cc=linux-block@vger.kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).