Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Sat, 10 Aug 2002 14:58:06 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Sat, 10 Aug 2002 14:58:06 -0400 Received: from dsl-213-023-020-194.arcor-ip.net ([213.23.20.194]:17048 "EHLO starship") by vger.kernel.org with ESMTP id ; Sat, 10 Aug 2002 14:58:05 -0400 Content-Type: text/plain; charset=US-ASCII From: Daniel Phillips To: ebiederm@xmission.com (Eric W. Biederman), Andrew Morton Subject: Re: large page patch (fwd) (fwd) Date: Sat, 10 Aug 2002 20:59:36 +0200 X-Mailer: KMail [version 1.3.2] Cc: Linus Torvalds , frankeh@watson.ibm.com, davidm@hpl.hp.com, David Mosberger , "David S. Miller" , gh@us.ibm.com, Martin.Bligh@us.ibm.com, wli@holomorpy.com, linux-kernel@vger.kernel.org References: <3D543645.8EBD2C36@zip.com.au> In-Reply-To: MIME-Version: 1.0 Content-Transfer-Encoding: 7BIT Message-Id: Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1254 Lines: 26 On Saturday 10 August 2002 20:20, Eric W. Biederman wrote: > Andrew Morton writes: > > The other worry is the ZONE_NORMAL space consumption of pte_chains. > > We've halved that, but it will still make high sharing levels > > unfeasible on the big ia32 machines. We are dependant upon large > > pages to solve that problem. (Resurrection of pte_highmem is in > > progress, but it doesn't work yet). > > There is a second method to address this. Pages can be swapped out > of the page tables and still remain in the page cache, the virtual > scan does this all of the time. This should allow for arbitrary > amounts of sharing. There is some overhead, in faulting the pages > back in but it is much better than cases that do not work. A simple > implementation would have a maximum pte_chain length. Oh gosh, nice point. We could put together a lovely cooked benchmark where copy_page_range just fails to copy all the mmap pages, which are most of them in the bash test. -- Daniel - 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/