From: Alexei Starovoitov <alexei.starovoitov@gmail.com>
To: "Toke Høiland-Jørgensen" <toke@redhat.com>
Cc: "David S. Miller" <davem@davemloft.net>,
Daniel Borkmann <daniel@iogearbox.net>,
Andrii Nakryiko <andrii@kernel.org>,
John Fastabend <john.fastabend@gmail.com>,
Lorenz Bauer <lmb@cloudflare.com>,
Network Development <netdev@vger.kernel.org>,
bpf <bpf@vger.kernel.org>, Kernel Team <kernel-team@fb.com>
Subject: Re: [RFC PATCH bpf-next] bpf: Introduce bpf_timer
Date: Mon, 24 May 2021 10:33:56 -0700 [thread overview]
Message-ID: <CAADnVQL8qw4OYQp+ozJpgPnimNYV7PtShZ-4tqdY7fTBhHf2ww@mail.gmail.com> (raw)
In-Reply-To: <CAADnVQL9xKcdCyR+-8irH07Ws7iKHjrE4XNb4OA7BkpBrkkEuA@mail.gmail.com>
On Sun, May 23, 2021 at 8:58 AM Alexei Starovoitov
<alexei.starovoitov@gmail.com> wrote:
>
> On Sun, May 23, 2021 at 4:48 AM Toke Høiland-Jørgensen <toke@redhat.com> wrote:
> >
> > Still wrapping my head around this, but one thing immediately sprang to
> > mind:
> >
> > > + * long bpf_timer_mod(struct bpf_timer *timer, u64 msecs)
> > > + * Description
> > > + * Set the timer expiration N msecs from the current time.
> > > + * Return
> > > + * zero
> >
> > Could we make this use nanoseconds (and wire it up to hrtimers) instead?
> > I would like to eventually be able to use this for pacing out network
> > packets, and msec precision is way too coarse for that...
>
> msecs are used to avoid exposing jiffies to bpf prog, since msec_to_jiffies
> isn't trivial to do in the bpf prog unlike the kernel.
> hrtimer would be great to support as well.
> It could be implemented via flags (which are currently zero only)
> but probably not as a full replacement for jiffies based timers.
> Like array vs hash. bpf_timer can support both.
After reading the hrtimer code I might take the above statement back...
hrtimer looks strictly better than timerwheel and jiffies.
It scales well and there are no concerns with overload,
since sys_nanonsleep and tcp are heavy users.
So I'm thinking to drop jiffies approach and do hrtimer only.
wdyt?
next prev parent reply other threads:[~2021-05-24 17:34 UTC|newest]
Thread overview: 80+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-20 18:55 [RFC PATCH bpf-next] bpf: Introduce bpf_timer Alexei Starovoitov
2021-05-21 14:38 ` Alexei Starovoitov
2021-05-21 21:37 ` Cong Wang
2021-05-23 16:01 ` Alexei Starovoitov
2021-05-24 8:45 ` Lorenz Bauer
2021-05-25 3:16 ` Cong Wang
2021-05-25 4:59 ` Cong Wang
2021-05-25 18:21 ` Alexei Starovoitov
2021-05-25 19:35 ` Jamal Hadi Salim
2021-05-25 19:57 ` Alexei Starovoitov
2021-05-25 21:09 ` Jamal Hadi Salim
2021-05-25 22:08 ` Alexei Starovoitov
2021-05-26 15:34 ` Jamal Hadi Salim
2021-05-26 16:58 ` Alexei Starovoitov
2021-05-26 18:25 ` Jamal Hadi Salim
2021-05-30 6:36 ` Cong Wang
2021-06-02 2:00 ` Alexei Starovoitov
2021-06-02 8:48 ` Toke Høiland-Jørgensen
2021-06-02 17:54 ` Martin KaFai Lau
2021-06-02 18:13 ` Kumar Kartikeya Dwivedi
2021-06-02 18:26 ` Alexei Starovoitov
2021-06-02 18:30 ` Kumar Kartikeya Dwivedi
2021-06-02 18:46 ` John Fastabend
2021-05-22 16:06 ` kernel test robot
2021-05-22 16:41 ` kernel test robot
2021-05-22 16:41 ` [RFC PATCH] bpf: bpf_timer_init_proto can be static kernel test robot
2021-05-23 11:48 ` [RFC PATCH bpf-next] bpf: Introduce bpf_timer Toke Høiland-Jørgensen
2021-05-23 15:58 ` Alexei Starovoitov
2021-05-24 8:42 ` Lorenz Bauer
2021-05-24 14:48 ` Alexei Starovoitov
2021-05-24 17:33 ` Alexei Starovoitov [this message]
2021-05-24 18:39 ` Toke Høiland-Jørgensen
2021-05-24 18:38 ` Toke Høiland-Jørgensen
2021-05-24 11:49 ` Lorenz Bauer
2021-05-24 14:56 ` Alexei Starovoitov
2021-05-24 19:13 ` Andrii Nakryiko
2021-05-25 5:22 ` Cong Wang
2021-05-25 19:47 ` Andrii Nakryiko
-- strict thread matches above, loose matches on Subject: below --
2021-04-01 4:26 [RFC Patch bpf-next] bpf: introduce bpf timer Cong Wang
2021-04-01 6:38 ` Song Liu
2021-04-01 17:28 ` Cong Wang
2021-04-01 20:17 ` Song Liu
2021-04-02 17:34 ` Cong Wang
2021-04-02 17:57 ` Song Liu
2021-04-02 19:08 ` Cong Wang
2021-04-02 19:43 ` Song Liu
2021-04-02 20:57 ` Cong Wang
2021-04-02 23:31 ` Song Liu
2021-04-05 23:49 ` Cong Wang
2021-04-06 1:07 ` Song Liu
2021-04-06 1:24 ` Cong Wang
2021-04-06 6:17 ` Song Liu
2021-04-06 16:48 ` Cong Wang
2021-04-06 23:36 ` Song Liu
2021-04-08 22:45 ` Cong Wang
2021-04-02 19:28 ` Alexei Starovoitov
2021-04-02 21:24 ` Cong Wang
2021-04-02 23:45 ` Alexei Starovoitov
2021-04-06 0:36 ` Cong Wang
2021-04-12 23:01 ` Alexei Starovoitov
2021-04-15 4:02 ` Cong Wang
2021-04-15 4:25 ` Alexei Starovoitov
2021-04-15 15:51 ` Cong Wang
2021-04-26 23:00 ` Cong Wang
2021-04-26 23:05 ` Alexei Starovoitov
2021-04-26 23:37 ` Cong Wang
2021-04-27 2:01 ` Alexei Starovoitov
2021-04-27 11:52 ` Jamal Hadi Salim
2021-04-27 16:36 ` Cong Wang
2021-04-27 18:33 ` Alexei Starovoitov
2021-05-09 5:37 ` Cong Wang
2021-05-10 20:55 ` Jamal Hadi Salim
2021-05-11 21:29 ` Cong Wang
2021-05-12 22:56 ` Jamal Hadi Salim
2021-05-11 5:05 ` Joe Stringer
2021-05-11 21:08 ` Cong Wang
2021-05-12 22:43 ` Jamal Hadi Salim
2021-05-13 18:45 ` Jamal Hadi Salim
2021-05-14 2:53 ` Cong Wang
2021-08-11 21:03 ` Joe Stringer
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