From: "Toke Høiland-Jørgensen" <toke@redhat.com>
To: Cong Wang <xiyou.wangcong@gmail.com>, Jakub Kicinski <kuba@kernel.org>
Cc: Yunsheng Lin <linyunsheng@huawei.com>,
David Miller <davem@davemloft.net>,
Vladimir Oltean <olteanv@gmail.com>,
Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Andrii Nakryiko <andriin@fb.com>,
Eric Dumazet <edumazet@google.com>, Wei Wang <weiwan@google.com>,
"Cong Wang ." <cong.wang@bytedance.com>,
Taehee Yoo <ap420073@gmail.com>,
Linux Kernel Network Developers <netdev@vger.kernel.org>,
LKML <linux-kernel@vger.kernel.org>,
linuxarm@openeuler.org, Marc Kleine-Budde <mkl@pengutronix.de>,
linux-can@vger.kernel.org, "Jason A. Donenfeld" <Jason@zx2c4.com>
Subject: Re: [RFC v2] net: sched: implement TCQ_F_CAN_BYPASS for lockless qdisc
Date: Wed, 17 Mar 2021 14:35:40 +0100 [thread overview]
Message-ID: <87eegddhsj.fsf@toke.dk> (raw)
In-Reply-To: <CAM_iQpXvVZxBRHF6PBDOYSOSCj08nPyfcY0adKuuTg=cqffV+w@mail.gmail.com>
Cong Wang <xiyou.wangcong@gmail.com> writes:
> On Mon, Mar 15, 2021 at 2:07 PM Jakub Kicinski <kuba@kernel.org> wrote:
>>
>> I thought pfifo was supposed to be "lockless" and this change
>> re-introduces a lock between producer and consumer, no?
>
> It has never been truly lockless, it uses two spinlocks in the ring buffer
> implementation, and it introduced a q->seqlock recently, with this patch
> now we have priv->lock, 4 locks in total. So our "lockless" qdisc ends
> up having more locks than others. ;) I don't think we are going to a
> right direction...
Just a thought, have you guys considered adopting the lockless MSPC ring
buffer recently introduced into Wireguard in commit:
8b5553ace83c ("wireguard: queueing: get rid of per-peer ring buffers")
Jason indicated he was willing to work on generalising it into a
reusable library if there was a use case for it. I haven't quite though
through the details of whether this would be such a use case, but
figured I'd at least mention it :)
-Toke
next prev parent reply other threads:[~2021-03-17 13:36 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-13 2:47 [PATCH RFC] net: sched: implement TCQ_F_CAN_BYPASS for lockless qdisc Yunsheng Lin
2021-03-14 0:03 ` Vladimir Oltean
2021-03-14 10:15 ` Marc Kleine-Budde
2021-03-15 0:50 ` Yunsheng Lin
2021-03-15 3:10 ` [RFC v2] " Yunsheng Lin
2021-03-15 12:29 ` Vladimir Oltean
2021-03-15 13:09 ` Marc Kleine-Budde
2021-03-15 18:53 ` Jakub Kicinski
2021-03-16 0:35 ` Yunsheng Lin
2021-03-16 3:47 ` [Linuxarm] " Yunsheng Lin
2021-03-16 8:15 ` Eric Dumazet
2021-03-16 12:36 ` Yunsheng Lin
2021-03-16 22:48 ` Cong Wang
2021-03-17 1:14 ` Yunsheng Lin
2021-03-17 13:35 ` Toke Høiland-Jørgensen [this message]
2021-03-17 13:45 ` Jason A. Donenfeld
2021-03-18 7:33 ` [Linuxarm] " Yunsheng Lin
2021-03-19 18:15 ` Cong Wang
2021-03-22 0:55 ` Yunsheng Lin
2021-03-24 1:49 ` Cong Wang
2021-03-24 2:36 ` Yunsheng Lin
2021-03-19 19:03 ` Jason A. Donenfeld
2021-03-22 1:05 ` Yunsheng Lin
2021-03-18 7:10 ` Ahmad Fatoum
2021-03-18 7:46 ` Yunsheng Lin
2021-03-18 9:09 ` Ahmad Fatoum
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