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From: Nick Piggin <nickpiggin@yahoo.com.au>
To: Zwane Mwaikambo <zwane@arm.linux.org.uk>
Cc: linux-kernel <linux-kernel@vger.kernel.org>
Subject: Re: [patch 1/5] i386 generic cmpxchg
Date: Mon, 31 Oct 2005 12:29:15 +1100	[thread overview]
Message-ID: <4365736B.4050506@yahoo.com.au> (raw)
In-Reply-To: <Pine.LNX.4.61.0510301157440.1526@montezuma.fsmlabs.com>

Zwane Mwaikambo wrote:
> Hi Nick,
> 
> On Sun, 30 Oct 2005, Nick Piggin wrote:
> 
> +#define cmpxchg(ptr,o,n)						\
> +({									\
> +	__typeof__(*(ptr)) __ret;					\
> +	if (likely(boot_cpu_data.x86 > 3))				\
> +		__ret = __cmpxchg((ptr), (unsigned long)(o),		\
> +					(unsigned long)(n), sizeof(*(ptr))); \
> +	else								\
> +		__ret = cmpxchg_386((ptr), (unsigned long)(o),		\
> +					(unsigned long)(n), sizeof(*(ptr))); \
> +	__ret;								\
> +})
> +#endif
> 
> How about something similar to the following to remove the branch on 
> optimised kernels?
> 

Hi Zwane,
This is only in the !CONFIG_X86_CMPXCHG case, though, so the branch would
only be there on a 386 kernel, I think?

-- 
SUSE Labs, Novell Inc.

Send instant messages to your online friends http://au.messenger.yahoo.com 

  reply	other threads:[~2005-10-31  1:27 UTC|newest]

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2005-10-30  0:41 [patches] lockless pagecache prep round 1 Nick Piggin
2005-10-30  0:43 ` [patch 1/5] i386 generic cmpxchg Nick Piggin
2005-10-30  0:44   ` [patch 2/5] atomic: atomic_cmpxchg Nick Piggin
2005-10-30  0:45     ` [patch 3/5] atomic: atomic_inc_not_zero Nick Piggin
2005-10-30  0:45       ` [patch 4/5] rcu file: use atomic primitives Nick Piggin
2005-10-30  0:47         ` [patch 5/5] atomic: dec_and_lock " Nick Piggin
2005-10-31 19:05       ` [patch 3/5] atomic: atomic_inc_not_zero Christoph Lameter
2005-11-01  4:34         ` Nick Piggin
2005-11-14 16:29       ` Paul Jackson
2005-11-14 21:48         ` Andrew Morton
2005-11-14 22:02           ` Paul Jackson
2005-11-14 23:09             ` Andrew Morton
2005-11-15  8:57               ` Nick Piggin
2005-10-30 20:12   ` [patch 1/5] i386 generic cmpxchg Zwane Mwaikambo
2005-10-31  1:29     ` Nick Piggin [this message]
2005-10-31  6:06       ` Zwane Mwaikambo
2005-10-31 19:09       ` Christoph Lameter
2005-10-30  0:48 ` [patche 1/5] radix tree: lookup_slot Nick Piggin
2005-10-30  0:49   ` [patch 2/5] radix tree: use prealloc Nick Piggin
2005-10-30  0:50     ` [patch 3/5] radix tree: cleanup Nick Piggin
2005-10-30  0:51       ` [patch 4/5] radix tree: clear_tags bail Nick Piggin
2005-10-30  0:57         ` [patch 5/5] radix tree: shrink Nick Piggin
2005-10-30  1:04 ` [patch 1/5] radix tree: lookup_slot Nick Piggin
  -- strict thread matches above, loose matches on Subject: below --
2005-11-05  7:55 [patch 0/4] atomic primitives again Nick Piggin
2005-11-05  7:56 ` [patch 1/5] i386: generic cmpxchg Nick Piggin

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