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From: Mitchell Blank Jr <mitch@sfgoth.com>
To: Andi Kleen <ak@suse.de>
Cc: "David S. Miller" <davem@davemloft.net>,
	rml@novell.com, akpm@osdl.org, linux-kernel@vger.kernel.org
Subject: Re: [patch] IBM HDAPS accelerometer driver, with probing.
Date: Fri, 26 Aug 2005 21:06:22 -0700	[thread overview]
Message-ID: <20050827040622.GH91880@gaz.sfgoth.com> (raw)
In-Reply-To: <p73vf1skt0g.fsf@verdi.suse.de>

Andi Kleen wrote:
> - it doesn't seem to help that much on modern CPUs with good
> branch prediction and big icaches anyways.

Really?  I would think that as pipelines get deeper (although that trend
seems to have stopped, thankfully) and Icache-miss penalties get relatively
larger we'd see unlikely() becoming MORE of a benefit, not less.  Storing
the used part of a "hot" function in 1 Icacheline instead of 4 seems like
an obvious win.

Personally I've never found unlikely() to be ugly; if anything I think
it serves as a nice little human-readable comment about whats going on
in the control-flow.  I guess I'm in the minority on that one, though.

-Mitch

  parent reply	other threads:[~2005-08-27  3:58 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2005-08-26 22:18 Robert Love
2005-08-26 22:44 ` Dmitry Torokhov
2005-08-26 23:37   ` Robert Love
2005-08-27  5:29     ` Arnaldo Carvalho de Melo
2005-08-27 14:45       ` Alan Cox
2005-08-26 22:58 ` Alexey Dobriyan
2005-08-26 23:15   ` David S. Miller
2005-08-27  2:34     ` Andi Kleen
2005-08-27  2:49       ` David S. Miller
2005-08-27  4:06       ` Mitchell Blank Jr [this message]
2005-08-27  5:34         ` Arnaldo Carvalho de Melo
2005-08-27  6:12           ` Dmitry Torokhov
2005-08-27 11:35             ` Alexey Dobriyan
2005-08-27 14:56               ` Andi Kleen

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