linux-kernel - Re: [PATCH] [patch 4a/4] ipc: sem optimise simple operations

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Message-ID: <20090816103127.GB8644@wotan.suse.de>
Date:	Sun, 16 Aug 2009 12:31:27 +0200
From:	Nick Piggin <npiggin@...e.de>
To:	Manfred Spraul <manfred@...orfullife.com>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Nadia Derbey <Nadia.Derbey@...l.net>,
	Pierre Peiffer <peifferp@...il.com>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] [patch 4a/4] ipc: sem optimise simple operations

On Sat, Aug 15, 2009 at 06:32:14PM +0200, Manfred Spraul wrote:
> It depends. After disabling inlining, including all helper functions 
> that differ:
> 
> My proposal: 301 bytes for update_queue.
> 
> "simple", only negv: 226 bytes
> "simple, negv+zero: 354 bytes
> simple+complex: 526 bytes.
> 
> Thus with only +-1 simple ops, your version uses less icache. If both 
> +-1 and 0 ops are used, your version uses more icache.

Don't forget that in that case, your version is badly suboptimal
due to the algorithmic complexity.
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