netdev - Re: [PATCH net-next v2] net: core: rework basic flow dissection helper

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Date:   Fri, 04 May 2018 13:26:34 -0400 (EDT)
From:   David Miller <davem@...emloft.net>
To:     pabeni@...hat.com
Cc:     netdev@...r.kernel.org, edumazet@...gle.com, jasowang@...hat.com
Subject: Re: [PATCH net-next v2] net: core: rework basic flow dissection
 helper

From: Paolo Abeni <pabeni@...hat.com>
Date: Fri,  4 May 2018 11:32:59 +0200

> When the core networking needs to detect the transport offset in a given
> packet and parse it explicitly, a full-blown flow_keys struct is used for
> storage.
> This patch introduces a smaller keys store, rework the basic flow dissect
> helper to use it, and apply this new helper where possible - namely in
> skb_probe_transport_header(). The used flow dissector data structures
> are renamed to match more closely the new role.
> 
> The above gives ~50% performance improvement in micro benchmarking around
> skb_probe_transport_header() and ~30% around eth_get_headlen(), mostly due
> to the smaller memset. Small, but measurable improvement is measured also
> in macro benchmarking.
> 
> v1 -> v2: use the new helper in eth_get_headlen() and skb_get_poff(),
>   as per DaveM suggestion
> 
> Suggested-by: David Miller <davem@...emloft.net>
> Signed-off-by: Paolo Abeni <pabeni@...hat.com>

Awesome.  Applied, thanks Paolo.