Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750726AbWBAJti (ORCPT ); Wed, 1 Feb 2006 04:49:38 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751141AbWBAJti (ORCPT ); Wed, 1 Feb 2006 04:49:38 -0500 Received: from smtp204.mail.sc5.yahoo.com ([216.136.130.127]:29012 "HELO smtp204.mail.sc5.yahoo.com") by vger.kernel.org with SMTP id S1750726AbWBAJth (ORCPT ); Wed, 1 Feb 2006 04:49:37 -0500 DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=s1024; d=yahoo.com.au; h=Received:Message-ID:Date:From:User-Agent:X-Accept-Language:MIME-Version:To:CC:Subject:References:In-Reply-To:Content-Type:Content-Transfer-Encoding; b=V6xJBSTP5MBLIoyDvHBTT8NNa4XnVhH/FKhZzO+4+UdEaPyNyQsgsljAnhfBrH6b8getAcEL7rk0jL6bnRnPuzqhyJTZgyg9HbB3P+g1DsauD58r8OLJjfv5wogOU6qLDWiIwprXa9JOxtqOSMd+APp/GX20zLDXOa8QryBSonM= ; Message-ID: <43E0842A.105@yahoo.com.au> Date: Wed, 01 Feb 2006 20:49:30 +1100 From: Nick Piggin User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.7.12) Gecko/20051007 Debian/1.7.12-1 X-Accept-Language: en MIME-Version: 1.0 To: Andi Kleen CC: Arjan van de Ven , Ray Bryant , Dave McCracken , Robin Holt , Hugh Dickins , Linux Kernel , Linux Memory Management Subject: Re: [PATCH/RFC] Shared page tables References: <200601240210.04337.ak@suse.de> <1138086398.2977.19.camel@laptopd505.fenrus.org> <200601240818.28696.ak@suse.de> In-Reply-To: <200601240818.28696.ak@suse.de> Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1219 Lines: 29 Andi Kleen wrote: > > Well, we first have to figure out if the shared page tables > are really worth all the ugly code, nasty locking and other problems > (inefficient TLB flush etc.) I personally would prefer > to make large pages work better before going down that path. > Other thing I wonder about - less efficient page table placement on NUMA systems might harm TLB miss latency on some systems (although we don't always do a great job of trying to localise these things yet anyway). Another is possible increased lock contention on widely shared page tables like libc. I agree that it is not something which needs to be rushed in any time soon. We've already got significant concessions and complexity in the memory manager for databases (hugepages, direct io / raw io) so a few % improvement on database performance doesn't put it on our must have list IMO. -- SUSE Labs, Novell Inc. Send instant messages to your online friends http://au.messenger.yahoo.com - 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/