From: Vlad Buslov <vladbu@mellanox•com>
To: Cong Wang <xiyou.wangcong@gmail•com>
Cc: Linux Kernel Network Developers <netdev@vger•kernel.org>,
Jamal Hadi Salim <jhs@mojatatu•com>,
Jiri Pirko <jiri@resnulli•us>, David Miller <davem@davemloft•net>
Subject: Re: [PATCH net-next] net: sched: don't release block->lock when dumping chains
Date: Tue, 26 Feb 2019 16:09:58 +0000 [thread overview]
Message-ID: <vbf36oamsz3.fsf@mellanox.com> (raw)
In-Reply-To: <CAM_iQpXQXMxWDTcFvEEXra_1uKujhbeb630_kPfBqO1R8uwYtA@mail.gmail.com>
On Tue 26 Feb 2019 at 00:15, Cong Wang <xiyou.wangcong@gmail•com> wrote:
> On Mon, Feb 25, 2019 at 7:45 AM Vlad Buslov <vladbu@mellanox•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@mellanox•com>
>> Suggested-by: Cong Wang <xiyou.wangcong@gmail•com>
>
> Thanks for the followup!
>
> Isn't it similar for __tcf_get_next_proto() in tcf_chain_dump()?
> And for tc_dump_tfilter()?
Not really. These two dump all tp filters and not just a template, which
is O(n) on number of filters and can be slow because it calls hw offload
API for each of them. Our typical use-case involves periodic filter dump
(to update stats) while multiple concurrent user-space threads are
updating filters, so it is important for them to be able to execute in
parallel.
next prev parent reply other threads:[~2019-02-26 16:10 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-02-25 15:45 [PATCH net-next] net: sched: don't release block->lock when dumping chains Vlad Buslov
2019-02-25 18:25 ` David Miller
2019-02-26 0:15 ` Cong Wang
2019-02-26 16:09 ` Vlad Buslov [this message]
2019-02-27 23:03 ` Cong Wang
2019-02-28 14:53 ` Vlad Buslov
2019-03-02 0:08 ` Cong Wang
2019-03-04 14:14 ` Vlad Buslov
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