On Wed, Jan 22, 2020 at 01:53:45PM -0800, Andrii Nakryiko wrote:
> On Tue, Jan 21, 2020 at 10:42 PM Martin KaFai Lau <kafai@xxxxxx> wrote:
> >
> > This patch adds a bpf_cubic example. Some highlights:
> > 1. CONFIG_HZ .kconfig map is used.
> > 2. In bictcp_update(), calculation is changed to use usec
> > resolution (i.e. USEC_PER_JIFFY) instead of using jiffies.
> > Thus, usecs_to_jiffies() is not used in the bpf_cubic.c.
> > 3. In bitctcp_update() [under tcp_friendliness], the original
> > "while (ca->ack_cnt > delta)" loop is changed to the equivalent
> > "ca->ack_cnt / delta" operation.
> >
> > Signed-off-by: Martin KaFai Lau <kafai@xxxxxx>
> > ---
>
> just my few cents below...
>
> [...]
>
> >
> > +static void test_cubic(void)
> > +{
> > + struct bpf_cubic *cubic_skel;
> > + struct bpf_link *link;
> > +
> > + cubic_skel = bpf_cubic__open_and_load();
> > + if (CHECK(!cubic_skel, "bpf_cubic__open_and_load", "failed\n"))
> > + return;
> > +
> > + link = bpf_map__attach_struct_ops(cubic_skel->maps.cubic);
>
> we should probably teach bpftool and libbpf to generate a link for
> struct_ops map and also auto-attach it as part of skeleton's attach...
> I'll add it if noone gets to it sooner
It is in my TODO list. I am happy to be beaten though ;)
>
> > + if (CHECK(IS_ERR(link), "bpf_map__attach_struct_ops", "err:%ld\n",
> > + PTR_ERR(link))) {
> > + bpf_cubic__destroy(cubic_skel);
> > + return;
> > + }
> > +
> > + do_test("bpf_cubic");
> > +
> > + bpf_link__destroy(link);
> > + bpf_cubic__destroy(cubic_skel);
> > +}
> > +
>
> [...]
>
> > +
> > +extern unsigned long CONFIG_HZ __kconfig __weak;
>
> you probably don't want __weak, if CONFIG_HZ is not defined in
> Kconfig, then something wrong is going on, probably, so it's better to
> error out early
Thanks for pointing it out. Will do.
