From: Nick Piggin <nickpiggin@yahoo.com.au>
To: Andrew Morton <akpm@osdl.org>
Cc: Daniel Walker <dwalker@mvista.com>,
linux-kernel@vger.kernel.org, hzhong@gmail.com
Subject: Re: [PATCH] Profile likely/unlikely macros
Date: Tue, 25 Apr 2006 20:11:00 +1000 [thread overview]
Message-ID: <444DF5B4.6030004@yahoo.com.au> (raw)
In-Reply-To: <20060424200657.0af43d6a.akpm@osdl.org>
Andrew Morton wrote:
> Daniel Walker <dwalker@mvista.com> wrote:
>
>> + if (likeliness->type & LIKELY_UNSEEN) {
>> + if (atomic_dec_and_test(&likely_lock)) {
>> + if (likeliness->type & LIKELY_UNSEEN) {
>> + likeliness->type &= (~LIKELY_UNSEEN);
>> + likeliness->next = likeliness_head;
>> + likeliness_head = likeliness;
>> + }
>> + }
>> + atomic_inc(&likely_lock);
>
>
> hm, good enough I guess. It does need a comment explaining why we
> don't just do spin_lock().
I guess it is so it can be used in NMIs and interrupts without turning
interrupts off (so is somewhat lightweight).
But please Daniel, just use spinlocks and trylock. This is buggy because
it doesn't get the required release consistency correct.
--
SUSE Labs, Novell Inc.
Send instant messages to your online friends http://au.messenger.yahoo.com
next prev parent reply other threads:[~2006-04-25 11:18 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-04-25 2:57 [PATCH] Profile likely/unlikely macros Daniel Walker
2006-04-25 3:06 ` Andrew Morton
2006-04-25 3:17 ` Daniel Walker
2006-04-25 10:11 ` Nick Piggin [this message]
2006-04-25 18:06 ` Hua Zhong
2006-04-25 18:23 ` Daniel Walker
2006-04-26 1:08 ` Nick Piggin
2006-04-26 9:56 ` Jörn Engel
2006-04-26 10:07 ` Nick Piggin
2006-04-25 23:14 ` Chen, Kenneth W
2006-04-25 9:19 ` Andreas Mohr
2006-05-01 22:05 ` Roland Dreier
-- strict thread matches above, loose matches on Subject: below --
2006-04-25 9:15 Mikael Pettersson
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