From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from ozlabs.org (ozlabs.org [IPv6:2401:3900:2:1::2]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id A8B601A0020 for ; Tue, 16 Sep 2014 10:49:13 +1000 (EST) 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 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> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Cc: linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , 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"