Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757859AbZDLBSJ (ORCPT ); Sat, 11 Apr 2009 21:18:09 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753470AbZDLBRy (ORCPT ); Sat, 11 Apr 2009 21:17:54 -0400 Received: from mail.lang.hm ([64.81.33.126]:47183 "EHLO bifrost.lang.hm" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751987AbZDLBRx (ORCPT ); Sat, 11 Apr 2009 21:17:53 -0400 Date: Sat, 11 Apr 2009 18:15:36 -0700 (PDT) From: david@lang.hm X-X-Sender: dlang@asgard.lang.hm To: Alan Cox cc: Grant Grundler , Linus Torvalds , Jeff Garzik , Linux IDE mailing list , LKML , Jens Axboe , Arjan van de Ven Subject: Re: Implementing NVMHCI... In-Reply-To: <20090412002527.631a5a89@lxorguk.ukuu.org.uk> Message-ID: References: <49E0D47B.9070205@garzik.org> <20090411203246.513a0892@lxorguk.ukuu.org.uk> <20090412002527.631a5a89@lxorguk.ukuu.org.uk> User-Agent: Alpine 1.10 (DEB 962 2008-03-14) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1693 Lines: 38 On Sun, 12 Apr 2009, Alan Cox wrote: >> We've abstract the DMA mapping/SG list handling enough that the >> block size should make no more difference than it does for the >> MTU size of a network. > > You need to start managing groups of pages in the vm and keeping them > together and writing them out together and paging them together even if > one of them is dirty and the other isn't. You have to deal with cases > where a process forks and the two pages are dirtied one in each but still > have to be written together. gaining this sort of ability would not be a bad thing. with current hardware (SSDs and raid arrays) you can very easily be in a situation where it's much cheaper to deal with a group of related pages as one group rather than processing them individually. this is just an extention of the same issue. David Lang > Alternatively you go for read-modify-write (nasty performance hit > especially for RAID or a log structured fs). > > Yes you can do it but it sure won't be pretty with a conventional fs. > Some of the log structured file systems have no problems with this and > some kinds of journalling can help but for a typical block file system > it'll suck. > -- > 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/ > -- 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/