From: Cong Wang <xiyou.wangcong@gmail.com>
To: Paolo Abeni <pabeni@redhat.com>
Cc: Kehuan Feng <kehuan.feng@gmail.com>,
Hillf Danton <hdanton@sina.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, 3 Sep 2020 10:43:38 -0700 [thread overview]
Message-ID: <CAM_iQpXZMeAGkq_=rG6KEabFNykszpRU_Hnv65Qk7yesvbRDrw@mail.gmail.com> (raw)
In-Reply-To: <dd73f551d1fc89e457ffabd106cbf0bf401b747b.camel@redhat.com>
On Thu, Sep 3, 2020 at 1:40 AM Paolo Abeni <pabeni@redhat.com> wrote:
>
> On Wed, 2020-09-02 at 22:01 -0700, Cong Wang wrote:
> > Can you test the attached one-line fix? I think we are overthinking,
> > probably all
> > we need here is a busy wait.
>
> I think that will solve, but I also think that will kill NOLOCK
> performances due to really increased contention.
Yeah, we somehow end up with more locks (seqlock, skb array lock)
for lockless qdisc. What an irony... ;)
>
> At this point I fear we could consider reverting the NOLOCK stuff.
> I personally would hate doing so, but it looks like NOLOCK benefits are
> outweighed by its issues.
I agree, NOLOCK brings more pains than gains. There are many race
conditions hidden in generic qdisc layer, another one is enqueue vs.
reset which is being discussed in another thread.
Thanks.
next prev parent reply other threads:[~2020-09-03 17:43 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 [this message]
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
2020-09-14 2:10 ` Yunsheng Lin
2020-09-17 19:52 ` Cong Wang
2020-09-18 2:06 ` Kehuan Feng
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to='CAM_iQpXZMeAGkq_=rG6KEabFNykszpRU_Hnv65Qk7yesvbRDrw@mail.gmail.com' \
--to=xiyou.wangcong@gmail.com \
--cc=albcamus@gmail.com \
--cc=davem@davemloft.net \
--cc=hdanton@sina.com \
--cc=john.fastabend@gmail.com \
--cc=johunt@akamai.com \
--cc=jonas.bonn@netrounds.com \
--cc=kehuan.feng@gmail.com \
--cc=linux-kernel@vger.kernel.org \
--cc=mzhivich@akamai.com \
--cc=netdev@vger.kernel.org \
--cc=pabeni@redhat.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.