From: "Björn Töpel" <bjorn@kernel.org>
To: "Jason A. Donenfeld" <Jason@zx2c4.com>
Cc: WireGuard mailing list <wireguard@lists.zx2c4.com>,
Dmitry Vyukov <dvyukov@google.com>
Subject: Re: [PATCH RFC v1] wireguard: queueing: get rid of per-peer ring buffers
Date: Thu, 18 Feb 2021 15:04:29 +0100 [thread overview]
Message-ID: <CAJ+HfNi9kaU1JN36gavVX7mh6tbuoFgUiXM03U7C5gLw_eiprQ@mail.gmail.com> (raw)
In-Reply-To: <CAHmME9r+c+e-ibBOwnFoz6Bnis4tBoeht63fqVdkKF-oTcEtMg@mail.gmail.com>
On Thu, 18 Feb 2021 at 14:53, Jason A. Donenfeld <Jason@zx2c4.com> wrote:
>
> Hey Bjorn,
>
> On Thu, Feb 18, 2021 at 2:50 PM Björn Töpel <bjorn@kernel.org> wrote:
> > > +
> > > +static void __wg_prev_queue_enqueue(struct prev_queue *queue, struct sk_buff *skb)
> > > +{
> > > + WRITE_ONCE(NEXT(skb), NULL);
> > > + smp_wmb();
> > > + WRITE_ONCE(NEXT(xchg_relaxed(&queue->head, skb)), skb);
> > > +}
> > > +
> >
> > I'll chime in with Toke; This MPSC and Dmitry's links really took me
> > to the "verify with pen/paper"-level! Thanks!
> >
> > I'd replace the smp_wmb()/_relaxed above with a xchg_release(), which
> > might perform better on some platforms. Also, it'll be a nicer pair
> > with the ldacq below. :-P In general, it would be nice with some
> > wording how the fences pair. It would help the readers (like me!) a
> > lot.
>
> Exactly. This is what's been in my dev tree for the last week or so:
>
Ah, nice!
> +static void __wg_prev_queue_enqueue(struct prev_queue *queue, struct
> sk_buff *skb)
> +{
> + WRITE_ONCE(NEXT(skb), NULL);
> + WRITE_ONCE(NEXT(xchg_release(&queue->head, skb)), skb);
> +}
>
> Look good?
>
Yes, exactly like that!
Cheers,
Björn
next prev parent reply other threads:[~2021-02-18 14:07 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-08 13:38 Jason A. Donenfeld
2021-02-09 8:24 ` Dmitry Vyukov
2021-02-09 15:44 ` Jason A. Donenfeld
2021-02-09 16:20 ` Dmitry Vyukov
2021-02-17 18:36 ` Toke Høiland-Jørgensen
2021-02-17 22:28 ` Jason A. Donenfeld
2021-02-17 23:41 ` Toke Høiland-Jørgensen
2021-02-18 13:49 ` Björn Töpel
2021-02-18 13:53 ` Jason A. Donenfeld
2021-02-18 14:04 ` Björn Töpel [this message]
2021-02-18 14:15 ` Jason A. Donenfeld
2021-02-18 15:12 ` Björn Töpel
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