netdev - Re: [PATCH net-next 2/2] net: use reciprocal_divide instead of reimplementing it

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Message-ID: <5225F3B7.2000202@redhat.com>
Date:	Tue, 03 Sep 2013 16:35:35 +0200
From:	Daniel Borkmann <dborkman@...hat.com>
To:	Eric Dumazet <eric.dumazet@...il.com>
CC:	davem@...emloft.net, netdev@...r.kernel.org,
	netfilter-devel@...r.kernel.org
Subject: Re: [PATCH net-next 2/2] net: use reciprocal_divide instead of reimplementing
 it

On 09/03/2013 04:02 PM, Eric Dumazet wrote:
> On Tue, 2013-09-03 at 12:26 +0200, Daniel Borkmann wrote:
>> Replace these places with reciprocal_divide() inline function instead of
>> reimplementing it each time, thus it will become easier to read. We do not
>> need to explicitly include its header as it's pulled in from linux/net.h
>> anyway.
>
> Sure, (((u64) hash * qcount) >> 32) happens to be
> reciprocal_divide(hash, qcount) but the result depends on hash being
> well distributed in [0 .. ~0U] space.
>
> So 'reciprocal' and 'divide' do not accurately describe this exact
> operation.
>
> I suggest making the thing more descriptive.
>
> (And discussed on lkml btw)

Sure, we can do that. Then lets drop these two for now.
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