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From: Cong Wang <xiyou.wangcong@gmail.com>
To: 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
Subject: Re: [RFC v2] net: sched: implement TCQ_F_CAN_BYPASS for lockless qdisc
Date: Tue, 16 Mar 2021 15:48:43 -0700	[thread overview]
Message-ID: <CAM_iQpXvVZxBRHF6PBDOYSOSCj08nPyfcY0adKuuTg=cqffV+w@mail.gmail.com> (raw)
In-Reply-To: <20210315115332.1647e92b@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com>

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...

Thanks.

  parent reply	other threads:[~2021-03-16 22:50 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 [this message]
2021-03-17  1:14       ` Yunsheng Lin
2021-03-17 13:35       ` Toke Høiland-Jørgensen
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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