Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1764886AbZFORrD (ORCPT ); Mon, 15 Jun 2009 13:47:03 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1763743AbZFORqw (ORCPT ); Mon, 15 Jun 2009 13:46:52 -0400 Received: from mail-bw0-f213.google.com ([209.85.218.213]:54822 "EHLO mail-bw0-f213.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752781AbZFORqv (ORCPT ); Mon, 15 Jun 2009 13:46:51 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=message-id:date:from:user-agent:mime-version:to:cc:subject :references:in-reply-to:content-type:content-transfer-encoding; b=WbFjlutfLCfySS/P26Ax2H6N9TcRzZtfLvWnYl5A+NHE/iaM91V23sT3L8eVJVSZeD MFULkxxtRjSWl5rbjUNndQKQDzmD4vsptC1IE8k0fA+PU3aMmRBILM4Go2WyTE6lnSjG 2NaG4vUOsGmg2rMVzTAGn7Hr/2FmFvAa7MZaY= Message-ID: <4A36881E.8010009@gmail.com> Date: Mon, 15 Jun 2009 19:42:54 +0200 From: Marco User-Agent: Thunderbird 2.0.0.19 (X11/20081227) MIME-Version: 1.0 To: Bryan Henderson CC: Artem Bityutskiy , Daniel Walker , Jamie Lokier , Linux Embedded , Linux FS Devel , Linux Kernel Subject: Re: [PATCH 00/14] Pramfs: Persistent and protected ram filesystem References: In-Reply-To: Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1265 Lines: 28 Bryan Henderson wrote: >> Marco wrote: >>> To enable direct >>> I/O at all times for all regular files requires either that >>> applications be modified to include the O_DIRECT flag on all file >>> opens, or that a new filesystem be used that always performs direct >>> I/O by default." >> This could be done as well by just introducing a "direct_io_only" >> mount option to a file-system which would need this feature. > > But it's possible that there's just no advantage to having a block device > in the stack here. When unix block devices were invented, their main > purpose was that they could reorder reads and writes and do buffering and > caching -- all things essential for disk drives. We don't want to stretch > the concept too far. > Yes I agree, we can't in this case talk about read and write reordering, buffering and caching because we're talking about something completely different from a classic disk. The issues of this kind of fs are more similar to the tmpfs issues. Marco -- 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/