netdev - Re: [RFC 0/3] ipsec: flow cache removal

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Message-Id: <20160927.221501.123624802268529925.davem@davemloft.net>
Date:   Tue, 27 Sep 2016 22:15:01 -0400 (EDT)
From:   David Miller <davem@...emloft.net>
To:     fw@...len.de
Cc:     netdev@...r.kernel.org
Subject: Re: [RFC 0/3] ipsec: flow cache removal

From: Florian Westphal <fw@...len.de>
Date: Tue, 27 Sep 2016 18:05:20 +0200

> Please do not apply these patches.

To be honest, I really want to :-)

> These are part of tests I made for the ipsec workshop at upcoming
> netdev 1.2 and I wanted to post these before the conference.
> 
> Short version is that there appear to be no major scalability issues
> anymore without flow cache.  Performance hit can be up to 30%
> in my tests (with 64 byte packets), however without flow cache we
> also avoid some undesirable effects when flow cache is constantly
> overloaded.
> 
> Seems most of the extra cost is mainly because of extra xfrm dst
> init/destruction (and not e.g. due to policy lookup).

Yes, if you have to allocate/destroy a dst every lookup then
it will hurt a lot.  Perhaps we can have a pre-cooked dst hung
off of some existing object as a first level strategy to avoid
this.

> Lets discuss more at the workshop.

Indeed.