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From: David Miller <davem@davemloft.net>
Subject: Re: [PATCH] net: remove tests on 64bit platforms
Date: Mon, 24 Jan 2011 23:30:57 -0800 (PST)
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From: Changli Gao <xiaosuo@gmail.com>
Date: Tue, 25 Jan 2011 12:21:38 +0800

> On 64bit platforms, >31 bit shifting of a unsigned long variable is
> valid, so we can remove the related boundary tests, which may slow
> down the CPU if branch prediction fails.

The key word is "may", you don't actually know if this kind of
change actually matters for performance in practice.

I'm not applying this.