Re: [PATCH] rcu-scale: change rcu-scale report.

[Han, Jiangong]

Sorry, my the comment is wrong, and the correct comment should be like 
below, and I had modify this, and I had resend one more applying review 
patch email for this.

Thanks for you time.

Br,

Jiangong.

----------------------------------
    rcu-scale: rcu-scale returns one less than the real number of gps 
in the dmesg report.

    The dmesg report on rcu-scale shows there are N grace periods, and gps
    are listed from 0 to N.
    This commit make writer_n_durations stores the counts of gps,
    and shows there are N+1 gps, change the listed gps index begin from 
0 to N.

    From
        [ 8306.087880] rcu-scale: writer 0 gps: 133
        ......
        [ 8307.864630] rcu-scale:    0 writer-duration:     0 44003961
        [ 8307.935711] rcu-scale:    0 writer-duration:     1 32003582
        ......
        [ 8316.472860] rcu-scale:    0 writer-duration:   132 28004391
        [ 8316.538498] rcu-scale:    0 writer-duration:   133 27996410

    to
        [ 8306.087880] rcu-scale: writer 0 gps: 134
        ......
        [ 8307.864630] rcu-scale:    0 writer-duration:     0 44003961
        [ 8307.935711] rcu-scale:    0 writer-duration:     1 32003582
        ......
        [ 8316.472860] rcu-scale:    0 writer-duration:   132 28004391
        [ 8316.538498] rcu-scale:    0 writer-duration:   133 27996410

----------------------------------



 2021/6/10 上午4:37, Paul E. McKenney 写道:
> [Please note: This e-mail is from an EXTERNAL e-mail address]
>
> On Sat, Jun 05, 2021 at 03:00:19PM +0800, Jiangong.Han wrote:
> > The report on rcu-scale shows there are N grace periods, and gps
> > are listed from 0 to N-1.
> > This commit make writer_n_durations stores the counts of gps,
> > change the listed gps index begin from 1 to N.
> >
> > From
> >      [ 8306.087880] rcu-scale: writer 0 gps: 133
> >      ......
> >      [ 8307.864630] rcu-scale:    0 writer-duration:     0 44003961
> >      [ 8307.935711] rcu-scale:    0 writer-duration:     1 32003582
> >      ......
> >      [ 8316.472860] rcu-scale:    0 writer-duration:   131 28004391
> >      [ 8316.538498] rcu-scale:    0 writer-duration:   132 27996410
> >
> > to
> >      [ 8306.087880] rcu-scale: writer 0 gps: 133
> >      ......
> >      [ 8307.864630] rcu-scale:    0 writer-duration:     1 44003961
> >      [ 8307.935711] rcu-scale:    0 writer-duration:     2 32003582
> >      ......
> >      [ 8316.472860] rcu-scale:    0 writer-duration:   132 28004391
> >      [ 8316.538498] rcu-scale:    0 writer-duration:   133 27996410
> >
> > Signed-off-by: Jiangong.Han <jiangong.han@xxxxxxxxxxxxx>
> You lost me on this one.  Why is this helpful?  And how does the change
> shown below actually result in the output shown above, given that
> rcu_scale_cleanup() still starts j at zero?
>
>                                                          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