Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752088AbYKNFXO (ORCPT ); Fri, 14 Nov 2008 00:23:14 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1750727AbYKNFW6 (ORCPT ); Fri, 14 Nov 2008 00:22:58 -0500 Received: from gw.goop.org ([64.81.55.164]:46550 "EHLO mail.goop.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750717AbYKNFW6 (ORCPT ); Fri, 14 Nov 2008 00:22:58 -0500 Message-ID: <491D0B2F.7050900@goop.org> Date: Thu, 13 Nov 2008 21:22:55 -0800 From: Jeremy Fitzhardinge User-Agent: Thunderbird 2.0.0.17 (X11/20081009) MIME-Version: 1.0 To: Nick Piggin CC: Andrew Morton , Linux Memory Management List , Linux Kernel Mailing List , "Pallipadi, Venkatesh" Subject: Re: [PATCH 1/2] mm: implement remap_pfn_range with apply_to_page_range References: <491C61B1.10005@goop.org> <200811141319.56713.nickpiggin@yahoo.com.au> <491CE8C6.4060000@goop.org> <200811141417.35724.nickpiggin@yahoo.com.au> In-Reply-To: <200811141417.35724.nickpiggin@yahoo.com.au> X-Enigmail-Version: 0.95.6 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1431 Lines: 36 Nick Piggin wrote: > On Friday 14 November 2008 13:56, Jeremy Fitzhardinge wrote: > >> Nick Piggin wrote: >> >>> This isn't performance critical to anyone? >>> >> The only difference should be between having the specialized code and an >> indirect function call, no? >> > > Indirect function call per pte. It's going to be slower surely. > Yes, though changing the calling convention to handle (up to) a whole page worth of ptes in one call would be fairly simple I think. > It is accepted practice to (carefully) duplicate the page table walking > functions in memory management code. I don't think that's a problem, > there is already so many instances of them (just be sure to stick to > exactly the same form and variable names, and any update or bugfix to > any of them is trivially applicable to all). > I think that's pretty awful practice, frankly, and I'd much prefer there to be a single iterator function which everyone uses. The open-coded iterators everywhere just makes it completely impractical to even think about other kinds of pagetable structures. (Of course we have at least two "general purpose" pagetable walkers now...) J -- 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/