netdev - Re: [PATCH net-next] net: sched: don't release block->lock when dumping chains

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Message-ID: <CAM_iQpXQXMxWDTcFvEEXra_1uKujhbeb630_kPfBqO1R8uwYtA@mail.gmail.com>
Date:   Mon, 25 Feb 2019 16:15:36 -0800
From:   Cong Wang <xiyou.wangcong@...il.com>
To:     Vlad Buslov <vladbu@...lanox.com>
Cc:     Linux Kernel Network Developers <netdev@...r.kernel.org>,
        Jamal Hadi Salim <jhs@...atatu.com>,
        Jiri Pirko <jiri@...nulli.us>,
        David Miller <davem@...emloft.net>
Subject: Re: [PATCH net-next] net: sched: don't release block->lock when
 dumping chains

On Mon, Feb 25, 2019 at 7:45 AM Vlad Buslov <vladbu@...lanox.com> wrote:
>
> Function tc_dump_chain() obtains and releases block->lock on each iteration
> of its inner loop that dumps all chains on block. Outputting chain template
> info is fast operation so locking/unlocking mutex multiple times is an
> overhead when lock is highly contested. Modify tc_dump_chain() to only
> obtain block->lock once and dump all chains without releasing it.
>
> Signed-off-by: Vlad Buslov <vladbu@...lanox.com>
> Suggested-by: Cong Wang <xiyou.wangcong@...il.com>

Thanks for the followup!

Isn't it similar for __tcf_get_next_proto() in tcf_chain_dump()?
And for tc_dump_tfilter()?