From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tejun Heo Subject: Re: [Ksummit-2008-discuss] Kernel Summit request for Discussion of future of ATA (libata) and IDE Date: Tue, 05 Aug 2008 08:49:09 +0900 Message-ID: <48979575.7090004@gmail.com> References: <48976168.3020804@shaw.ca> <489768A1.8000501@garzik.org> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: Received: from ti-out-0910.google.com ([209.85.142.185]:1155 "EHLO ti-out-0910.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753931AbYHDXtt (ORCPT ); Mon, 4 Aug 2008 19:49:49 -0400 Received: by ti-out-0910.google.com with SMTP id b6so565303tic.23 for ; Mon, 04 Aug 2008 16:49:47 -0700 (PDT) In-Reply-To: <489768A1.8000501@garzik.org> Sender: linux-ide-owner@vger.kernel.org List-Id: linux-ide@vger.kernel.org To: Jeff Garzik Cc: Robert Hancock , Bartlomiej Zolnierkiewicz , ksummit-2008-discuss@lists.linux-foundation.org, linux-kernel , James Bottomley , linux-ide , Alan Cox Jeff Garzik wrote: > Robert Hancock wrote: >> Alan Cox wrote: >>>> * There are still corner case in libata core - PIO is dead slow >>>> compared to drivers/ide/, >>> There are two there - libata keeps IRQs blocked for longer in PIO mode as >>> well which is a factor for realtime that needs looking at, as well as >>> using 16bit not 32bit I/O for most devices (which is trivial to fix). The >>> IRQ masking stuff is more complex and old IDE handles it far better for >>> PIO on non shared IRQ interfaces. That is actually probably the most >>> complicated thing to address of the stuff you'd want to do if you were >>> going to kill off old IDE. >> I was looking into the 32-bit PIO issue a bit yesterday. It looks like >> some of the VLB libata drivers are doing this internally already, so it >> shouldn't be hard to do this in the core. Only question is how we know >> generically if the controller can do it or not? It looks like in old >> IDE, a few controllers explicitly disable it, but it appears that it >> doesn't default to on for any controller, so it's possible there are >> others on which it doesn't work. Presumably anything on an actual 16-bit >> bus (ISA, LPC, etc.) wouldn't like it, to start with. > > FWIW there is already a patch from Willy Terreau (sp?) to add 32-bit I/O. > > I queued it for "later" because it had some issues that Alan pointed > out, IIRC. I definitely want to push it in, though. Jeff, have your thoughts about PIO IRQ disable handling changed yet? I don't really see any better way than doing it like IDE. Thanks. -- tejun