From mboxrd@z Thu Jan  1 00:00:00 1970
From: David Miller <davem@davemloft.net>
Subject: Re: [PATCH net-next] fib: use __fls() on non null argument
Date: Tue, 07 Aug 2012 16:27:50 -0700 (PDT)
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From: Eric Dumazet <eric.dumazet@gmail.com>
Date: Tue, 07 Aug 2012 22:45:47 +0200

> [PATCH v2 net-next] fib: use __fls() on non null argument
> 
> __fls(x) is a bit faster than fls(x), granted we know x is non null.
> 
> As Ben Hutchings pointed out, fls(x) = __fls(x) + 1
> 
> Signed-off-by: Eric Dumazet <edumazet@google.com>
> Cc: Ben Hutchings <bhutchings@solarflare.com>

Applied.

This is, btw, the most expensive part of fib_trie on sparc64 since we
really don't have a universal way to do this in a hardware instruction
and therefore we end up with the branch-heavy software implementation :-/

So if anyone can come up with a way to eliminate this fls() entirely,
you will be my hero.