From: Nick Piggin <nickpiggin@yahoo.com.au>
To: Arjan van de Ven <arjan@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>,
Andrew Morton <akpm@osdl.org>, Jeff Garzik <jeff@garzik.org>,
linux-kernel@vger.kernel.org, torvalds@osdl.org
Subject: Re: [PATCH] ext3_clear_inode(): avoid kfree(NULL)
Date: Sun, 25 Jun 2006 02:06:29 +1000 [thread overview]
Message-ID: <449D6305.4060303@yahoo.com.au> (raw)
In-Reply-To: <1151158295.3181.46.camel@laptopd505.fenrus.org>
Arjan van de Ven wrote:
>>The jne is expected to fail, so we will always continue to 0x13. Now is
>>this a problem with x86/x86_64?
>
>
> I'm not saying there is a problem; likely/unlikely do have an effect for
> sure, it's just not a "make it free" thing....
On x86 I think the main saving is the icache one. However I guess
gcc would try to align with the branch prediction behaviour for
unknown branches too.
The microoptimisation is that the call avoids the unlikely branch
in kfree. Maybe for x86 this isn't going to matter, but for some
architectures in might.
--
SUSE Labs, Novell Inc.
Send instant messages to your online friends http://au.messenger.yahoo.com
next prev parent reply other threads:[~2006-06-24 16:06 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <200606231502.k5NF2jfO007109@hera.kernel.org>
2006-06-23 18:51 ` [PATCH] ext3_clear_inode(): avoid kfree(NULL) Jeff Garzik
2006-06-23 21:24 ` Andrew Morton
2006-06-24 12:11 ` Arjan van de Ven
2006-06-24 12:20 ` Steven Rostedt
2006-06-24 12:27 ` Arjan van de Ven
2006-06-24 12:33 ` Steven Rostedt
2006-06-24 12:46 ` Arjan van de Ven
2006-06-24 12:51 ` Steven Rostedt
2006-06-24 12:53 ` Arjan van de Ven
2006-06-24 13:07 ` Steven Rostedt
2006-06-24 14:11 ` Arjan van de Ven
2006-06-24 16:06 ` Nick Piggin [this message]
2006-06-24 16:49 ` Jeremy Fitzhardinge
2006-06-24 16:55 ` Arjan van de Ven
2006-06-24 16:19 ` Pekka Enberg
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