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From: "Toke Høiland-Jørgensen" <toke@redhat.com>
To: Pete Heist <pete@heistp.net>, Cake List <cake@lists.bufferbloat.net>
Subject: Re: [Cake] lockup with multiple cake instances on 3.16.7
Date: Wed, 30 Jan 2019 23:59:16 +0100	[thread overview]
Message-ID: <87zhrhiwfv.fsf@toke.dk> (raw)
In-Reply-To: <15FB76CC-44B2-496B-80EC-8D00AD2AF9B7@heistp.net>

Pete Heist <pete@heistp.net> writes:

> I’m seeing a lockup with cake on 3.16.7 with 64-bit Intel when adding
> more than 4 cake instances. I’m using cake and tc-adv from head. Does
> anyone have an idea what this could be?

Looks like it's a compatibility issue with old kernels. Could you please
check if the latest commit in the github repo fixes this? :)

The explanation, copied from that commit:

> The qdisc stats dumping was changed in 4.8 (by commit
> edb09eb17ed89eaa82a52dd306beac93e292b485) to be lockless and moving the
> responsibility for taking the qdisc root lock into the qdisc itself. Cake
> inherited this from FQ-CoDel, but it leads to deadlocks on old kernels
> where the core stats dumping code still takes the root qdisc lock.


-Toke

  reply	other threads:[~2019-01-30 22:59 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-01-30  8:58 Pete Heist
2019-01-30 22:59 ` Toke Høiland-Jørgensen [this message]
2019-01-31  7:15   ` Pete Heist
2019-01-31 14:53     ` Toke Høiland-Jørgensen
2019-01-31 20:25       ` Pete Heist
2019-01-31 23:09         ` Toke Høiland-Jørgensen
2019-01-31 23:18           ` Pete Heist
2019-01-31 23:10         ` Pete Heist
2019-01-31 23:18           ` Toke Høiland-Jørgensen
2019-01-31 23:23             ` Pete Heist
2019-01-31 23:31               ` Toke Høiland-Jørgensen

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