From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750967AbWDMWiv (ORCPT ); Thu, 13 Apr 2006 18:38:51 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751072AbWDMWiv (ORCPT ); Thu, 13 Apr 2006 18:38:51 -0400 Received: from gate.crashing.org ([63.228.1.57]:51360 "EHLO gate.crashing.org") by vger.kernel.org with ESMTP id S1750939AbWDMWiv (ORCPT ); Thu, 13 Apr 2006 18:38:51 -0400 Subject: Re: [PATCH] [2/2] POWERPC: Lower threshold for DART enablement to 1GB, V2 From: Benjamin Herrenschmidt To: Olof Johansson Cc: Muli Ben-Yehuda , paulus@samba.org, linuxppc-dev@ozlabs.org, linux-kernel@vger.kernel.org In-Reply-To: <20060413222721.GN24769@pb15.lixom.net> References: <20060413020559.GC24769@pb15.lixom.net> <20060413022809.GD24769@pb15.lixom.net> <20060413025233.GE24769@pb15.lixom.net> <20060413064027.GH10412@granada.merseine.nu> <1144925149.4935.14.camel@localhost.localdomain> <20060413160712.GG24769@pb15.lixom.net> <1144961515.4935.22.camel@localhost.localdomain> <20060413222721.GN24769@pb15.lixom.net> Content-Type: text/plain Date: Fri, 14 Apr 2006 08:38:31 +1000 Message-Id: <1144967911.4935.35.camel@localhost.localdomain> Mime-Version: 1.0 X-Mailer: Evolution 2.6.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 2006-04-13 at 17:27 -0500, Olof Johansson wrote: > On Fri, Apr 14, 2006 at 06:51:55AM +1000, Benjamin Herrenschmidt wrote: > > > an improvement with the DART thanks to virtual merging. Currently, we > > pay a cost due to our stupid invalidate mecanism that we should really > > fix by shooting the TLB directly. > > What was keeping me from implementing this before was the lack of public > documentation on how to do it. Has that changed? I'd be happy to do the > implementation. Darwin has the macros to access the TLB though it doesn't use them... I suppose I can get the necessary doco bit from the microelectronics folks for the CPC925, that should apply to U3 as well, though U4 has a different format afaik. I'll dig and will come back to you. > > Also have you made sure all your > > additions for handling crappy hardware are nicely wrapped in unlikely() > > statements ? :) > > I would expect the dynamic predictor to work quite well on this. I'm not > worried about the overhead of the tests as much as the overhead of > having to enable the DART for smaller configs. If benchmark profiling > shows different down the road then we can add them. Ok. Ben.