From: "Han, Jiangong" <Jiangong.Han@windriver.com>
To: paulmck@kernel.org
Cc: dave@stgolabs.net, josh@joshtriplett.org, rostedt@goodmis.org,
mathieu.desnoyers@efficios.com, jiangshanlai@gmail.com,
joel@joelfernandes.org, linux-kernel@vger.kernel.org,
rcu@vger.kernel.org
Subject: Re: [PATCH v3] rcuscale: Console output claims too few grace periods
Date: Fri, 25 Jun 2021 09:44:43 +0800 [thread overview]
Message-ID: <0f251dba-0e0d-970f-904a-24b540a175be@windriver.com> (raw)
In-Reply-To: <20210624164045.GU4397@paulmck-ThinkPad-P17-Gen-1>
Hi, Paul,
I think your words are much clear than mine, no missings, thanks for
your help. :)
Thanks for your quickly response again.
Br,
Jiangong
在 2021/6/25 上午12:40, Paul E. McKenney 写道:
> [Please note: This e-mail is from an EXTERNAL e-mail address]
>
> On Thu, Jun 24, 2021 at 10:34:24PM +0800, Jiangong.Han wrote:
>> 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>
> I already have it queued in -rcu here:
>
> 4c154a910344 ("rcuscale: Console output claims too few grace periods")
>
> Or did you find an error in my wordsmithed version of your commit log?
> If so, please point out the error explicitly. (It looks identical to me,
> but I could easily be missing something.)
>
> Thanx, Paul
>
>> ---
>> 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
>>
prev parent reply other threads:[~2021-06-25 2:00 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-24 14:34 [PATCH v3] rcuscale: Console output claims too few grace periods Jiangong.Han
2021-06-24 16:40 ` Paul E. McKenney
2021-06-25 1:44 ` Han, Jiangong [this message]
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