From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758582AbaIPAtP (ORCPT ); Mon, 15 Sep 2014 20:49:15 -0400 Received: from ozlabs.org ([103.22.144.67]:37799 "EHLO ozlabs.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753393AbaIPAtO (ORCPT ); Mon, 15 Sep 2014 20:49:14 -0400 Date: Tue, 16 Sep 2014 10:49:14 +1000 From: Anton Blanchard To: benh@kernel.crashing.org, paulus@samba.org, michael@ellerman.id.au, torvalds@linux-foundation.org Cc: linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org Subject: [PATCH 2/2] powerpc: Use CONFIG_ARCH_HAS_FAST_MULTIPLIER Message-ID: <20140916104914.66abcca1@kryten> In-Reply-To: <20140916104749.35b84da8@kryten> References: <20140916104749.35b84da8@kryten> X-Mailer: Claws Mail 3.9.3 (GTK+ 2.24.23; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org I ran some tests to compare hash_64 using shifts and multiplies. The results: POWER6: ~2x slower POWER7: ~2x faster POWER8: ~2x faster Now we have a proper config option, select CONFIG_ARCH_HAS_FAST_MULTIPLIER on POWER7 and POWER8. Signed-off-by: Anton Blanchard --- Index: b/arch/powerpc/platforms/Kconfig.cputype =================================================================== --- a/arch/powerpc/platforms/Kconfig.cputype +++ b/arch/powerpc/platforms/Kconfig.cputype @@ -116,10 +116,12 @@ config POWER6_CPU config POWER7_CPU bool "POWER7" depends on PPC_BOOK3S_64 + select ARCH_HAS_FAST_MULTIPLIER config POWER8_CPU bool "POWER8" depends on PPC_BOOK3S_64 + select ARCH_HAS_FAST_MULTIPLIER config E5500_CPU bool "Freescale e5500"