Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261516AbVCCGA3 (ORCPT ); Thu, 3 Mar 2005 01:00:29 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261513AbVCCF7K (ORCPT ); Thu, 3 Mar 2005 00:59:10 -0500 Received: from gate.crashing.org ([63.228.1.57]:32468 "EHLO gate.crashing.org") by vger.kernel.org with ESMTP id S261544AbVCCF44 (ORCPT ); Thu, 3 Mar 2005 00:56:56 -0500 Subject: Re: Page fault scalability patch V18: Drop first acquisition of ptl From: Benjamin Herrenschmidt To: "David S. Miller" Cc: Paul Mackerras , Andrew Morton , clameter@sgi.com, Linux Kernel list , linux-ia64@vger.kernel.org, Anton Blanchard In-Reply-To: <20050302213831.7e6449eb.davem@davemloft.net> References: <20050302174507.7991af94.akpm@osdl.org> <20050302185508.4cd2f618.akpm@osdl.org> <20050302201425.2b994195.akpm@osdl.org> <16934.39386.686708.768378@cargo.ozlabs.ibm.com> <20050302213831.7e6449eb.davem@davemloft.net> Content-Type: text/plain Date: Thu, 03 Mar 2005 16:54:08 +1100 Message-Id: <1109829248.5679.178.camel@gaston> Mime-Version: 1.0 X-Mailer: Evolution 2.0.3 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 887 Lines: 22 > However, if this pte_cmpxchg() thing is used for removing access, then > sparc64 can't use it. In such a case a race in the TLB handler would > result in using an invalid PTE. I could "spin" on some lock bit, but > there is no way I'm adding instructions to the carefully constructed > TLB miss handler assembler on sparc64 just for that :-) Can't you add a lock bit in the PTE itself like we do on ppc64 hash refill ? Ok, ok, you don't want to add instructions, fair enough :) On ppc64, I had to do that to close some nasty race we had in the hash refill, but it came almost for free as we already had an atomic loop in there. Ben. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/