From mboxrd@z Thu Jan  1 00:00:00 1970
From: Eric Dumazet <dada1@cosmosbay.com>
Subject: Re: [PATCH] x86: percpu_to_op() misses memory and flags clobbers
Date: Wed, 01 Apr 2009 20:47:41 +0200
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Cc: Ingo Molnar <mingo@elte.hu>, Tejun Heo <htejun@gmail.com>,
	linux kernel <linux-kernel@vger.kernel.org>,
	Linux Netdev List <netdev@vger.kernel.org>,
	Joe Perches <joe@perches.com>,
	Rusty Russell <rusty@rustcorp.com.au>
To: Jeremy Fitzhardinge <jeremy@goop.org>
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Jeremy Fitzhardinge a =E9crit :
> Eric Dumazet wrote:
>> +#define percpu_inc(var)        percpu_to_op0("inc", per_cpu__##var)
>> +#define percpu_dec(var)        percpu_to_op0("dec", per_cpu__##var)
>>  =20
>=20
> There's probably not a lot of value in this.  The Intel and AMD
> optimisation guides tend to deprecate inc/dec in favour of using
> add/sub, because the former can cause pipeline stalls due to its part=
ial
> flags update.
>=20
>    J

Sure, but this saves one byte per call, this is probably why we still u=
se
inc/dec in so many places...