From: Segher Boessenkool <segher@kernel.crashing.org>
To: Christophe Leroy <christophe.leroy@c-s.fr>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>,
Paul Mackerras <paulus@samba.org>,
Michael Ellerman <mpe@ellerman.id.au>,
scottwood@freescale.com, linuxppc-dev@lists.ozlabs.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 2/2] powerpc32: optimise csum_partial() loop
Date: Wed, 5 Aug 2015 19:30:59 -0500 [thread overview]
Message-ID: <20150806003059.GD18479@gate.crashing.org> (raw)
In-Reply-To: <67cf476f657e87b2ea586951a57ae3ba3c1e3c0c.1435655733.git.christophe.leroy@c-s.fr>
On Wed, Aug 05, 2015 at 03:29:35PM +0200, Christophe Leroy wrote:
> On the 8xx, load latency is 2 cycles and taking branches also takes
> 2 cycles. So let's unroll the loop.
This is not true for most other 32-bit PowerPC; this patch makes
performance worse on e.g. 6xx/7xx/7xxx. Let's not!
Segher
next prev parent reply other threads:[~2015-08-06 0:32 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-08-05 13:29 [PATCH v2 0/2] powerpc32: Optimise csum_partial() Christophe Leroy
2015-08-05 13:29 ` [PATCH v2 1/2] powerpc32: optimise a few instructions in csum_partial() Christophe Leroy
2015-08-05 13:29 ` [PATCH v2 2/2] powerpc32: optimise csum_partial() loop Christophe Leroy
2015-08-06 0:30 ` Segher Boessenkool [this message]
2015-08-06 2:31 ` Scott Wood
2015-08-06 4:39 ` Segher Boessenkool
2015-08-06 22:45 ` Scott Wood
2015-08-06 23:25 ` Segher Boessenkool
2015-08-17 10:56 ` leroy christophe
2015-08-17 11:00 ` leroy christophe
2015-08-17 13:05 ` leroy christophe
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