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
> + 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
> +#define HZ CONFIG_HZ
> +#define USEC_PER_MSEC 1000UL
> +#define USEC_PER_SEC 1000000UL
> +#define USEC_PER_JIFFY (USEC_PER_SEC / HZ)
> +
[...]
