netdev - Re: [PATCH bpf-next] samples: bpf: refactor xdp_sample_pkts

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Date:   Wed, 9 Sep 2020 02:38:26 +0900
From:   "Daniel T. Lee" <danieltimlee@...il.com>
To:     Andrii Nakryiko <andrii.nakryiko@...il.com>
Cc:     Daniel Borkmann <daniel@...earbox.net>,
        Alexei Starovoitov <ast@...nel.org>,
        Networking <netdev@...r.kernel.org>, bpf <bpf@...r.kernel.org>
Subject: Re: [PATCH bpf-next] samples: bpf: refactor xdp_sample_pkts_kern with
 BTF-defined map

On Wed, Sep 9, 2020 at 8:24 AM Andrii Nakryiko
<andrii.nakryiko@...il.com> wrote:
>
> On Sat, Sep 5, 2020 at 8:41 AM Daniel T. Lee <danieltimlee@...il.com> wrote:
> >
> > Most of the samples were converted to use the new BTF-defined MAP as
> > they moved to libbbpf, but some of the samples were missing.
> >
> > Instead of using the previous BPF MAP definition, this commit refactors
> > xdp_sample_pkts_kern MAP definition with the new BTF-defined MAP format.
> >
> > Signed-off-by: Daniel T. Lee <danieltimlee@...il.com>
> > ---
> >  samples/bpf/xdp_sample_pkts_kern.c | 12 ++++++------
> >  1 file changed, 6 insertions(+), 6 deletions(-)
> >
> > diff --git a/samples/bpf/xdp_sample_pkts_kern.c b/samples/bpf/xdp_sample_pkts_kern.c
> > index 33377289e2a8..b15172b7d455 100644
> > --- a/samples/bpf/xdp_sample_pkts_kern.c
> > +++ b/samples/bpf/xdp_sample_pkts_kern.c
> > @@ -7,12 +7,12 @@
> >  #define SAMPLE_SIZE 64ul
> >  #define MAX_CPUS 128
> >
> > -struct bpf_map_def SEC("maps") my_map = {
> > -       .type = BPF_MAP_TYPE_PERF_EVENT_ARRAY,
> > -       .key_size = sizeof(int),
> > -       .value_size = sizeof(u32),
> > -       .max_entries = MAX_CPUS,
> > -};
> > +struct {
> > +       __uint(type, BPF_MAP_TYPE_PERF_EVENT_ARRAY);
> > +       __uint(key_size, sizeof(int));
> > +       __uint(value_size, sizeof(u32));
> > +       __uint(max_entries, MAX_CPUS);
>
> if you drop max_entries property, libbpf will set it to the maximum
> configured number of CPUs on the host, which is what you probably
> want. Do you might sending v2 without MAX_CPUS (check if macro is
> still used anywhere else). Thanks!
>

Thanks for your time and effort for the review.

I'll check and send the next version of patch.


> > +} my_map SEC(".maps");
> >
> >  SEC("xdp_sample")
> >  int xdp_sample_prog(struct xdp_md *ctx)
> > --
> > 2.25.1
> >

-- 
Best,
Daniel T. Lee