From: Segher Boessenkool <segher@kernel.crashing.org>
To: Anton Blanchard <anton@samba.org>
Cc: paulus@samba.org, linuxppc-dev@lists.ozlabs.org
Subject: Re: [PATCH v2] powerpc: Speed up clear_page by unrolling it
Date: Thu, 2 Oct 2014 09:17:55 -0500 [thread overview]
Message-ID: <20141002141755.GA13453@gate.crashing.org> (raw)
In-Reply-To: <20141002154421.62073027@kryten>
On Thu, Oct 02, 2014 at 03:44:21PM +1000, Anton Blanchard wrote:
> This assumes cacheline sizes won't grow beyond 512 bytes or
> page sizes wont drop below 1kB,
Or a combination of those.
> Michael found that some versions of gcc produce quite bad code
> (all multiplies), so we give gcc a hand by using shifts and adds.
You can make the code a lot less cluttered as well as making the
generated code independent of compiler version by writing the setup
of twox..eightx in the asm block itself.
Segher
prev parent reply other threads:[~2014-10-02 14:18 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-10-02 5:44 [PATCH v2] powerpc: Speed up clear_page by unrolling it Anton Blanchard
2014-10-02 14:17 ` Segher Boessenkool [this message]
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