From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from na01-bn1-obe.outbound.protection.outlook.com (mail-bn1bbn0102.outbound.protection.outlook.com [157.56.111.102]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id E9B381A001E for ; Tue, 29 Sep 2015 08:07:31 +1000 (AEST) Date: Mon, 28 Sep 2015 17:07:17 -0500 From: Scott Wood To: Christophe Leroy CC: Benjamin Herrenschmidt , Paul Mackerras , Michael Ellerman , , Subject: Re: [PATCH v2 01/25] powerpc/8xx: Save r3 all the time in DTLB miss handler Message-ID: <20150928220717.GA6161@home.buserror.net> References: <2d35de4435e873f23d37e3b5b5fb34c64421f136.1442939410.git.christophe.leroy@c-s.fr> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" In-Reply-To: <2d35de4435e873f23d37e3b5b5fb34c64421f136.1442939410.git.christophe.leroy@c-s.fr> List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Tue, Sep 22, 2015 at 06:50:29PM +0200, Christophe Leroy wrote: > We are spending between 40 and 160 cycles with a mean of 65 cycles in > the TLB handling routines (measured with mftbl) so make it more > simple althought it adds one instruction. > > Signed-off-by: Christophe Leroy Does this just make it simpler or does it make it faster? What is the performance impact? Is the performance impact seen with or without CONFIG_8xx_CPU6 enabled? Without it, it looks like you're adding an mtspr/mfspr combo in order to replace one mfspr. -Scott