From: Cong Wang <xiyou.wangcong@gmail.com>
To: Kehuan Feng <kehuan.feng@gmail.com>
Cc: Hillf Danton <hdanton@sina.com>, Paolo Abeni <pabeni@redhat.com>,
Jike Song <albcamus@gmail.com>, Josh Hunt <johunt@akamai.com>,
Jonas Bonn <jonas.bonn@netrounds.com>,
Michael Zhivich <mzhivich@akamai.com>,
David Miller <davem@davemloft.net>,
John Fastabend <john.fastabend@gmail.com>,
LKML <linux-kernel@vger.kernel.org>,
Netdev <netdev@vger.kernel.org>
Subject: Re: Packet gets stuck in NOLOCK pfifo_fast qdisc
Date: Thu, 10 Sep 2020 13:19:01 -0700 [thread overview]
Message-ID: <CAM_iQpUq9-wja3JHz9+TMeXGyAOmJfZDxWUZJ9v25i7vd0Z-Wg@mail.gmail.com> (raw)
In-Reply-To: <CACS=qqLKSpnRrgROm8jzzFid3MH97phPXWsk28b371dfu0mnVA@mail.gmail.com>
On Thu, Sep 3, 2020 at 8:21 PM Kehuan Feng <kehuan.feng@gmail.com> wrote:
> I also tried Cong's patch (shown below on my tree) and it could avoid
> the issue (stressing for 30 minutus for three times and not jitter
> observed).
Thanks for verifying it!
>
> --- ./include/net/sch_generic.h.orig 2020-08-21 15:13:51.787952710 +0800
> +++ ./include/net/sch_generic.h 2020-09-03 21:36:11.468383738 +0800
> @@ -127,8 +127,7 @@
> static inline bool qdisc_run_begin(struct Qdisc *qdisc)
> {
> if (qdisc->flags & TCQ_F_NOLOCK) {
> - if (!spin_trylock(&qdisc->seqlock))
> - return false;
> + spin_lock(&qdisc->seqlock);
> } else if (qdisc_is_running(qdisc)) {
> return false;
> }
>
> I am not actually know what you are discussing above. It seems to me
> that Cong's patch is similar as disabling lockless feature.
From performance's perspective, yeah. Did you see any performance
downgrade with my patch applied? It would be great if you can compare
it with removing NOLOCK. And if the performance is as bad as no
NOLOCK, then we can remove the NOLOCK bit for pfifo_fast, at least
for now.
Thanks.
next prev parent reply other threads:[~2020-09-10 20:19 UTC|newest]
Thread overview: 47+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-09 6:46 Packet gets stuck in NOLOCK pfifo_fast qdisc Jonas Bonn
2019-10-09 19:14 ` Paolo Abeni
2019-10-10 6:27 ` Jonas Bonn
2019-10-11 0:39 ` Jonas Bonn
2020-06-23 13:42 ` Michael Zhivich
2020-06-30 19:14 ` Josh Hunt
2020-07-01 7:53 ` Jonas Bonn
2020-07-01 16:05 ` Cong Wang
2020-07-01 19:58 ` Cong Wang
2020-07-01 22:02 ` Josh Hunt
2020-07-02 6:14 ` Jonas Bonn
2020-07-02 9:45 ` Paolo Abeni
2020-07-02 18:08 ` Josh Hunt
2020-07-07 14:18 ` Paolo Abeni
2020-07-08 20:16 ` Cong Wang
2020-07-09 9:20 ` Paolo Abeni
2020-07-08 20:33 ` Zhivich, Michael
2020-08-20 7:43 ` Jike Song
2020-08-20 18:13 ` Josh Hunt
[not found] ` <20200822032800.16296-1-hdanton@sina.com>
2020-08-25 2:18 ` Fengkehuan Feng
[not found] ` <20200825032312.11776-1-hdanton@sina.com>
2020-08-25 7:14 ` Fengkehuan Feng
[not found] ` <20200825162329.11292-1-hdanton@sina.com>
2020-08-26 2:38 ` Kehuan Feng
[not found] ` <CACS=qqKptAQQGiMoCs1Zgs9S4ZppHhasy1AK4df2NxnCDR+vCw@mail.gmail.com>
[not found] ` <5f46032e.1c69fb81.9880c.7a6cSMTPIN_ADDED_MISSING@mx.google.com>
2020-08-27 6:56 ` Kehuan Feng
[not found] ` <20200827125747.5816-1-hdanton@sina.com>
2020-08-28 1:45 ` Kehuan Feng
2020-09-03 5:01 ` Cong Wang
2020-09-03 8:39 ` Paolo Abeni
2020-09-03 17:43 ` Cong Wang
2020-09-04 5:07 ` John Fastabend
2020-09-10 20:15 ` Cong Wang
2020-09-10 21:07 ` John Fastabend
2020-09-10 21:40 ` Paolo Abeni
2021-04-02 19:25 ` Jiri Kosina
2021-04-02 19:33 ` Josh Hunt
[not found] ` <20210403003537.2032-1-hdanton@sina.com>
2021-04-03 12:23 ` Jiri Kosina
2021-04-06 0:55 ` Yunsheng Lin
2021-04-06 7:06 ` Michal Kubecek
2021-04-06 10:13 ` Juergen Gross
2021-04-06 12:17 ` Yunsheng Lin
2021-04-06 1:49 ` Cong Wang
2021-04-06 2:46 ` Yunsheng Lin
2021-04-06 7:31 ` Michal Kubecek
2021-04-06 12:24 ` Yunsheng Lin
[not found] ` <20200903101957.428-1-hdanton@sina.com>
2020-09-04 3:20 ` Kehuan Feng
2020-09-10 20:19 ` Cong Wang [this message]
2020-09-14 2:10 ` Yunsheng Lin
2020-09-17 19:52 ` Cong Wang
2020-09-18 2:06 ` Kehuan Feng
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