Re: [RFC PATCH bpf-next] bpf: Introduce bpf_timer

On Fri, May 21, 2021 at 2:37 PM Cong Wang [off-list ref] wrote:

Hi, Alexei

On Thu, May 20, 2021 at 11:52 PM Alexei Starovoitov
[off-list ref] wrote:

quoted

From: Alexei Starovoitov <ast@kernel.org>

Why do you intentionally keep people in the original discussion
out of your CC? Remember you are the one who objected the
idea by questioning its usefulness no matter how I hard I tried
to explain? I am glad you changed your mind, but it does not
mean you should forget to credit other people.

I didn't change my mind and I still object to your stated
_reasons_ for timers.

quoted

Introduce 'struct bpf_timer' that can be embedded in most BPF map types
and helpers to operate on it:
long bpf_timer_init(struct bpf_timer *timer, void *callback, int flags)
long bpf_timer_mod(struct bpf_timer *timer, u64 msecs)
long bpf_timer_del(struct bpf_timer *timer)

Like we discussed, this approach would make the timer harder
to be independent of other eBPF programs, which is a must-have
for both of our use cases (mine and Jamal's). Like you explained,
this requires at least another program array, a tail call, a mandatory
prog pinning to work.

That is simply not true.

So, why do you prefer to make it harder to use?

BTW, I have a V2 to send out soon and will keep you in CC, which
still creates timers from user-space.

Don't bother.