linux-kernel - Re: x86: A fast way to check capabilities of the current cpu

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Date:	Wed, 15 Dec 2010 22:48:33 +0100
From:	Miguel Ojeda <miguel.ojeda.sandonis@...il.com>
To:	"H. Peter Anvin" <hpa@...or.com>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Christoph Lameter <cl@...ux.com>, Tejun Heo <tj@...nel.org>,
	Pekka Enbeerg <penberg@...helsinki.fi>,
	linux-kernel@...r.kernel.org,
	Eric Dumazet <eric.dumazet@...il.com>,
	Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
Subject: Re: x86: A fast way to check capabilities of the current cpu

On Wed, Dec 15, 2010 at 10:39 PM, H. Peter Anvin <hpa@...or.com> wrote:
> On 12/15/2010 01:30 PM, Miguel Ojeda wrote:
>>
>> In this case it this_cpu_*_test_bit() return an int, but they act as a
>> bool and are used in if()s; where is the catch?
>>
>
> If they aren't, and are stored in a variable for whatever reason, then
> the || form will generate additional instructions to booleanize the
> value for no good reason.

Thanks! I suppose that is the 't' of being "a fast way" ;-)

>
>        -hpa
>
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