netdev - Re: [PATCH v3] net:Add sysctl_max_skb

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Date:	Wed, 3 Feb 2016 13:03:54 -0800
From:	Alexander Duyck <alexander.duyck@...il.com>
To:	Eric Dumazet <eric.dumazet@...il.com>
Cc:	Hans Westgaard Ry <hans.westgaard.ry@...cle.com>,
	"David S. Miller" <davem@...emloft.net>,
	Alexey Kuznetsov <kuznet@....inr.ac.ru>,
	James Morris <jmorris@...ei.org>,
	Hideaki YOSHIFUJI <yoshfuji@...ux-ipv6.org>,
	Patrick McHardy <kaber@...sh.net>,
	Tom Herbert <tom@...bertland.com>,
	Pablo Neira Ayuso <pablo@...filter.org>,
	Eric Dumazet <edumazet@...gle.com>,
	Florian Westphal <fw@...len.de>, Jiri Pirko <jiri@...nulli.us>,
	Michal Hocko <mhocko@...e.com>,
	Linus Lüssing <linus.luessing@...3.blue>,
	Hannes Frederic Sowa <hannes@...essinduktion.org>,
	Herbert Xu <herbert@...dor.apana.org.au>,
	Tejun Heo <tj@...nel.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Alexey Kodanev <alexey.kodanev@...cle.com>,
	Håkon Bugge <haakon.bugge@...cle.com>,
	open list <linux-kernel@...r.kernel.org>,
	"open list:NETWORKING [GENERAL]" <netdev@...r.kernel.org>
Subject: Re: [PATCH v3] net:Add sysctl_max_skb_frags

On Wed, Feb 3, 2016 at 11:23 AM, Eric Dumazet <eric.dumazet@...il.com> wrote:
> On Wed, 2016-02-03 at 10:24 -0800, Alexander Duyck wrote:
>
>> If this is only meant to be a performance modification and is only
>> really targeted at TCP TSO/GRO then all I ask is that we use a name
>> like tcp_max_gso_frags and relocate the sysctl to the TCP section.
>> Otherwise if we are actually going to try to scope this out on a wider
>> level and limit all frags which is what the name implies then the
>> patch set needs to make a better attempt at covering all cases where
>> it may apply.
>
>
> This is the goal.
>
> Other skb providers (like tun and af_packet) will also use this optional
> limit.
>
> I fail to see why Hans should send a complete patch series.

You realize that conflicts with what anybody else would be told.  What
was provided in this patch is a half solution, and it may cause bigger
messes since it is unclear exactly how this sysctl is meant to be
used.

> We will send followup patches, as we always did.
>
> I will send the GRO change for example.
>
> So please keep a sysctl name _without_ TCP in it, it really has nothing
> to do with TCP.

In the end I am not the one you have to convince.  I have simply
stated my opinion, and I guess we will have to agree to disagree.  It
is entirely up to Dave if he wants to apply it or not.  I have slides
I need to work on for next week.. :-)

- Alex