From: "Jiangong.Han" <jiangong.han@windriver.com>
To: dave@stgolabs.net, paulmck@kernel.org, josh@joshtriplett.org,
rostedt@goodmis.org, mathieu.desnoyers@efficios.com,
jiangshanlai@gmail.com, joel@joelfernandes.org
Cc: linux-kernel@vger.kernel.org, rcu@vger.kernel.org,
"Jiangong.Han" <jiangong.han@windriver.com>
Subject: [PATCH v3] rcuscale: Console output claims too few grace periods
Date: Thu, 24 Jun 2021 22:34:24 +0800 [thread overview]
Message-ID: <20210624143424.16158-1-jiangong.han@windriver.com> (raw)
The rcuscale console output claims N grace periods, numbered from zero
to N, which means that there were really N+1 grace periods. The root
cause of this bug is that rcu_scale_writer() stores the number of the
last grace period (numbered from zero) into writer_n_durations[me]
instead of the number of grace periods. This commit therefore assigns
the actual number of grace periods to writer_n_durations[me], and also
makes the corresponding adjustment to the loop outputting per-grace-period
measurements.
Sample of old console output:
rcu-scale: writer 0 gps: 133
......
rcu-scale: 0 writer-duration: 0 44003961
rcu-scale: 0 writer-duration: 1 32003582
......
rcu-scale: 0 writer-duration: 132 28004391
rcu-scale: 0 writer-duration: 133 27996410
Sample of new console output:
rcu-scale: writer 0 gps: 134
......
rcu-scale: 0 writer-duration: 0 44003961
rcu-scale: 0 writer-duration: 1 32003582
......
rcu-scale: 0 writer-duration: 132 28004391
rcu-scale: 0 writer-duration: 133 27996410
Signed-off-by: Jiangong.Han <jiangong.han@windriver.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
---
kernel/rcu/rcuscale.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/kernel/rcu/rcuscale.c b/kernel/rcu/rcuscale.c
index dca51fe9c73f..2cc34a22a506 100644
--- a/kernel/rcu/rcuscale.c
+++ b/kernel/rcu/rcuscale.c
@@ -487,7 +487,7 @@ rcu_scale_writer(void *arg)
if (gp_async) {
cur_ops->gp_barrier();
}
- writer_n_durations[me] = i_max;
+ writer_n_durations[me] = i_max + 1;
torture_kthread_stopping("rcu_scale_writer");
return 0;
}
@@ -561,7 +561,7 @@ rcu_scale_cleanup(void)
wdpp = writer_durations[i];
if (!wdpp)
continue;
- for (j = 0; j <= writer_n_durations[i]; j++) {
+ for (j = 0; j < writer_n_durations[i]; j++) {
wdp = &wdpp[j];
pr_alert("%s%s %4d writer-duration: %5d %llu\n",
scale_type, SCALE_FLAG,
--
2.17.1
next reply other threads:[~2021-06-24 14:35 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-24 14:34 Jiangong.Han [this message]
2021-06-24 16:40 ` [PATCH v3] rcuscale: Console output claims too few grace periods Paul E. McKenney
2021-06-25 1:44 ` Han, Jiangong
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=20210624143424.16158-1-jiangong.han@windriver.com \
--to=jiangong.han@windriver.com \
--cc=dave@stgolabs.net \
--cc=jiangshanlai@gmail.com \
--cc=joel@joelfernandes.org \
--cc=josh@joshtriplett.org \
--cc=linux-kernel@vger.kernel.org \
--cc=mathieu.desnoyers@efficios.com \
--cc=paulmck@kernel.org \
--cc=rcu@vger.kernel.org \
--cc=rostedt@goodmis.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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.