linux-kernel - Re: [PATCH] samples, bpf: Add duration option D for sampleip

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Date:   Wed, 23 Nov 2022 13:38:07 -0800
From:   Andrii Nakryiko <andrii.nakryiko@...il.com>
To:     Kang Minchul <tegongkang@...il.com>
Cc:     Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Andrii Nakryiko <andrii@...nel.org>,
        Martin KaFai Lau <martin.lau@...ux.dev>,
        Song Liu <song@...nel.org>, Yonghong Song <yhs@...com>,
        John Fastabend <john.fastabend@...il.com>,
        KP Singh <kpsingh@...nel.org>, bpf@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] samples, bpf: Add duration option D for sampleip

On Sat, Nov 19, 2022 at 8:06 AM Kang Minchul <tegongkang@...il.com> wrote:
>
> Thanks for your reply.
>
> 2022년 11월 18일 (금) 오전 8:26, Andrii Nakryiko <andrii.nakryiko@...il.com>님이 작성:
> >
> > On Tue, Nov 15, 2022 at 10:46 PM Kang Minchul <tegongkang@...il.com> wrote:
> > >
> > > Although sampleip program can handle three options,
> > > (-F for frequency, duration, and -h for help)
> > > currently there is no independent option for duration.
> >
> > Because it's positional argument, which is very clearly documented by
> > usage(). What's wrong with that and why do you want to change this?
> Yes, but I'm not sure why only 'duration' should be a positional argument.
>
> I don't think it is 'wrong', but I think it's better to treat
> 'duration' just as same as 'frequency' because
>  frequency and duration are two independent things in this case.
> (duration is not dependent on frequency)
>
> So I thought making an option for duration like below
>
> $ sudo ./samples/bpf/sampleip -F <Frequecny> -D <Duration>
>
> is better than below.
>
> $ sudo ./samples/bpf/sampleip -F <Frequecny> <Duration>
>
> I am not insisting strongly on this, so if I have misunderstood something,
> I'll respect the existing way.
>

I think it's just a common convention (e.g., iostat has the similar
approach). Let's keep it as is.


> Regards,
>
> Kang Minchul
> > >
> > > This patch adds option -D for duration like below:
> > >
> > > $ sudo ./samples/bpf/sampleip -h
> > > USAGE: sampleip [-F freq] [-D duration]
> > >        -F freq       # sample frequency (Hertz), default 99
> > >        -D duration   # sampling duration (seconds), default 5
> > >
> > > $ sudo ./samples/bpf/sampleip -F 120
> > > Sampling at 120 Hertz for 5 seconds. Ctrl-C also ends.
> > > ADDR                KSYM                          COUNT
> > > ...
> > >
> > > $ sudo ./samples/bpf/sampleip -D 7
> > > Sampling at 99 Hertz for 7 seconds. Ctrl-C also ends.
> > > ADDR                KSYM                          COUNT
> > > ...
> > >
> > > $ sudo ./samples/bpf/sampleip -F 120 -D 7
> > > Sampling at 120 Hertz for 7 seconds. Ctrl-C also ends.
> > > ADDR                KSYM                          COUNT
> > > ...
> > >
> > > Signed-off-by: Kang Minchul <tegongkang@...il.com>
> > > ---
> > >  samples/bpf/sampleip_user.c | 13 +++++++------
> > >  1 file changed, 7 insertions(+), 6 deletions(-)
> > >
> > > diff --git a/samples/bpf/sampleip_user.c b/samples/bpf/sampleip_user.c
> > > index 921c505bb567..ce6aadd496e1 100644
> > > --- a/samples/bpf/sampleip_user.c
> > > +++ b/samples/bpf/sampleip_user.c
> > > @@ -28,9 +28,9 @@ static int nr_cpus;
> > >
> > >  static void usage(void)
> > >  {
> > > -       printf("USAGE: sampleip [-F freq] [duration]\n");
> > > -       printf("       -F freq    # sample frequency (Hertz), default 99\n");
> > > -       printf("       duration   # sampling duration (seconds), default 5\n");
> > > +       printf("USAGE: sampleip [-F freq] [-D duration]\n");
> > > +       printf("       -F freq       # sample frequency (Hertz), default 99\n");
> > > +       printf("       -D duration   # sampling duration (seconds), default 5\n");
> > >  }
> > >
> > >  static int sampling_start(int freq, struct bpf_program *prog,
> > > @@ -145,19 +145,20 @@ int main(int argc, char **argv)
> > >         char filename[256];
> > >
> > >         /* process arguments */
> > > -       while ((opt = getopt(argc, argv, "F:h")) != -1) {
> > > +       while ((opt = getopt(argc, argv, "F:D:h")) != -1) {
> > >                 switch (opt) {
> > >                 case 'F':
> > >                         freq = atoi(optarg);
> > >                         break;
> > > +               case 'D':
> > > +                       secs = atoi(optarg);
> > > +                       break;
> > >                 case 'h':
> > >                 default:
> > >                         usage();
> > >                         return 0;
> > >                 }
> > >         }
> > > -       if (argc - optind == 1)
> > > -               secs = atoi(argv[optind]);
> > >         if (freq == 0 || secs == 0) {
> > >                 usage();
> > >                 return 1;
> > > --
> > > 2.34.1
> > >