From: Eric Dumazet <dada1@cosmosbay.com>
To: Jeremy Fitzhardinge <jeremy@goop.org>
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>
Subject: Re: [PATCH] x86: percpu_to_op() misses memory and flags clobbers
Date: Wed, 01 Apr 2009 20:47:41 +0200 [thread overview]
Message-ID: <49D3B6CD.2030908@cosmosbay.com> (raw)
In-Reply-To: <49D3AD61.5090206@goop.org>
Jeremy Fitzhardinge a écrit :
> 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)
>>
>
> 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 partial
> flags update.
>
> J
Sure, but this saves one byte per call, this is probably why we still use
inc/dec in so many places...
next prev parent reply other threads:[~2009-04-01 18:48 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-04-01 8:13 [PATCH] x86: percpu_to_op() misses memory and flags clobbers Eric Dumazet
2009-04-01 9:02 ` Jeremy Fitzhardinge
2009-04-01 10:14 ` Eric Dumazet
2009-04-01 16:12 ` Ingo Molnar
2009-04-01 16:41 ` Jeremy Fitzhardinge
2009-04-01 16:44 ` Ingo Molnar
2009-04-01 17:13 ` Eric Dumazet
2009-04-01 18:07 ` Jeremy Fitzhardinge
2009-04-01 18:47 ` Eric Dumazet [this message]
2009-04-02 9:52 ` Herbert Xu
2009-04-02 14:12 ` Jeremy Fitzhardinge
2009-04-01 18:44 ` [RFC] percpu: convert SNMP mibs to new infra Eric Dumazet
2009-04-02 0:13 ` Tejun Heo
2009-04-02 4:05 ` Ingo Molnar
2009-04-02 8:07 ` [PATCH] " Eric Dumazet
2009-04-03 0:39 ` Tejun Heo
2009-04-03 17:10 ` Ingo Molnar
2009-04-02 5:04 ` [RFC] " Rusty Russell
2009-04-02 5:19 ` Eric Dumazet
2009-04-02 11:46 ` Rusty Russell
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