netdev - Re: [PATCH net] inet: frags: re-introduce skb coalescing for local delivery

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Message-ID: <20190807002832.q4xvst4i4jj6fwst@breakpoint.cc>
Date:   Wed, 7 Aug 2019 02:28:32 +0200
From:   Florian Westphal <fw@...len.de>
To:     Guillaume Nault <gnault@...hat.com>
Cc:     netdev@...r.kernel.org, Florian Westphal <fw@...len.de>,
        Eric Dumazet <edumazet@...gle.com>,
        Peter Oskolkov <posk@...gle.com>,
        Alexander Aring <alex.aring@...il.com>
Subject: Re: [PATCH net] inet: frags: re-introduce skb coalescing for local
 delivery

Guillaume Nault <gnault@...hat.com> wrote:
> Before commit d4289fcc9b16 ("net: IP6 defrag: use rbtrees for IPv6
> defrag"), a netperf UDP_STREAM test[0] using big IPv6 datagrams (thus
> generating many fragments) and running over an IPsec tunnel, reported
> more than 6Gbps throughput. After that patch, the same test gets only
> 9Mbps when receiving on a be2net nic (driver can make a big difference
> here, for example, ixgbe doesn't seem to be affected).
> 
> By reusing the IPv4 defragmentation code, IPv6 lost fragment coalescing
> (IPv4 fragment coalescing was dropped by commit 14fe22e33462 ("Revert
> "ipv4: use skb coalescing in defragmentation"")).

[..]

> This patch is quite conservative and only coalesces skbs for local
> IPv4 and IPv6 delivery (in order to avoid changing skb geometry when
> forwarding). Coalescing could be extended in the future if need be, as
> more scenarios would probably benefit from it.

No objections from my side, so:

Acked-by: Florian Westphal <fw@...len.de>