netdev - Re: [PATCH] net: Make synchronize_net() be expedited only when it's really need

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Message-ID: <CANn89iJsRJEM4w6R+B7or4MS9cU8oaPZ2=qyk+yKFOFzCTjVwQ@mail.gmail.com>
Date:   Tue, 23 Jan 2018 09:13:55 -0800
From:   Eric Dumazet <edumazet@...gle.com>
To:     Kirill Tkhai <ktkhai@...tuozzo.com>
Cc:     Eric Dumazet <eric.dumazet@...il.com>,
        netdev <netdev@...r.kernel.org>,
        David Miller <davem@...emloft.net>,
        David Ahern <dsahern@...il.com>,
        Florian Westphal <fw@...len.de>,
        Xin Long <lucien.xin@...il.com>,
        Daniel Borkmann <daniel@...earbox.net>,
        mschiffer@...verse-factory.net, jakub.kicinski@...ronome.com,
        Vladislav Yasevich <vyasevich@...il.com>,
        Jiri Benc <jbenc@...hat.com>
Subject: Re: [PATCH] net: Make synchronize_net() be expedited only when it's
 really need

On Tue, Jan 23, 2018 at 9:09 AM, Kirill Tkhai <ktkhai@...tuozzo.com> wrote:
> On 23.01.2018 19:58, Eric Dumazet wrote:
>>>
>>> Your original patch did not provide any test results. Only the fact synchronize_rcu_expedited()
>>> completes faster than plain synchronize_rcu(). But this is an obvious fact
>>> just because of the design, and this is described even in the documentation.
>>> Beleive me, I don't want to offend you this words, but it's strange you hadn't
>>> gone the way you suggest me.
>>
>> Well, I guess you missed the fine changelog.
>>
>> Please carefully read it :
>>
>> https://git.kernel.org/pub/scm/linux/kernel/git/davem/net.git/commit/?id=be3fc413da9eb17cce0991f214ab019d16c88c41
>
> This is just what I said.

You said that I provided no test results. But I really did. That is
included in the changelog.

You provided no test results, but some confusing changelog that left
the reader for whatever interpretation.

>
>> And you' ll noticed I had an Ack from Paul E. McKenney, the RCU maintainer.
> I won't ask you either you had the ACK before you sent the patch, because
> the answer is obvious.
>
> Anyway, this doesn't matter. I don't insist on the fix for this place.
> If you're so negative on this question, we may leave everything as is,
> and live with this ambiguous place several years more.

Your patch has potential serious issues and you refuse to address my feedback,
I am not sure we will progress.

If you are ready to leave this for following years, why this patch was
targeting net tree, I wonder.