netdev - Re: [RFC PATCH 17/17] fib_trie: Add tracking value for suffix length

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Message-Id: <20141222.133255.250370768177880358.davem@davemloft.net>
Date:	Mon, 22 Dec 2014 13:32:55 -0500 (EST)
From:	David Miller <davem@...emloft.net>
To:	alexander.h.duyck@...hat.com
Cc:	netdev@...r.kernel.org
Subject: Re: [RFC PATCH 17/17] fib_trie: Add tracking value for suffix
 length

From: Alexander Duyck <alexander.h.duyck@...hat.com>
Date: Mon, 22 Dec 2014 09:42:38 -0800

> This change adds a tracking value for the maximum suffix length of all
> prefixes stored in any given tnode.  With this value we can determine if we
> need to backtrace or not based on if the suffix is greater than the pos
> value.
> 
> By doing this we can reduce the CPU overhead for lookups in the local table
> as many of the prefixes there are 32b long and have a suffix length of 0
> meaning we can immediately backtrace to the root node without needing to
> test any of the nodes between it and where we ended up.
> 
> Signed-off-by: Alexander Duyck <alexander.h.duyck@...hat.com>

This is a really nice optimization.
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