Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758311AbZDSM5l (ORCPT ); Sun, 19 Apr 2009 08:57:41 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1757809AbZDSM5c (ORCPT ); Sun, 19 Apr 2009 08:57:32 -0400 Received: from srv5.dvmed.net ([207.36.208.214]:35210 "EHLO mail.dvmed.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751862AbZDSM5c (ORCPT ); Sun, 19 Apr 2009 08:57:32 -0400 Message-ID: <49EB1FB3.5000609@garzik.org> Date: Sun, 19 Apr 2009 08:57:23 -0400 From: Jeff Garzik User-Agent: Thunderbird 2.0.0.21 (X11/20090320) MIME-Version: 1.0 To: Michael Tokarev CC: Mark Lord , =?UTF-8?B?Um9nw6lyaW8gQnJpdG8=?= , linux-kernel@vger.kernel.org Subject: Re: Quick question about libata and hdparm References: <49EB1A33.7050808@rtr.ca> <49EB1C9C.3000105@msgid.tls.msk.ru> In-Reply-To: <49EB1C9C.3000105@msgid.tls.msk.ru> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Spam-Score: -4.4 (----) X-Spam-Report: SpamAssassin version 3.2.5 on srv5.dvmed.net summary: Content analysis details: (-4.4 points, 5.0 required) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1344 Lines: 38 Michael Tokarev wrote: > Mark Lord wrote: > [] >> Nearly all of the hdparm flags work fine with libata and SATA/PATA >> drives. >> Among the *very few* that do not, are the -m and -d flags. -c will be >> working >> in the newest kernels, but not yet in most distro kernels. >> >> The -d flag is not permitted by libata, as the kernel prefers to >> completely >> dictate DMA / PIO, and it does do a rather good job of it. > > Well, the kernel does a good job here in *almost* all cases. > The problematic case is when a device has some bad/unreadable > blocks/sectors. When such a place occurs on read, libata > (or whatever it is) performs several retries, each time > using "less aggressive" settings - like reducing UDMA and > PIO mode till the lowest possible PIO/33. And the device > stays in that mode until reboot, even if the problematic > sector has been relocated. So it'd be nice to be able to > reset the mode back in such cases. Do you have a log? libata worries about speed changes for CRC errors and the like, not for media errors that involve sector relocation. Jeff -- 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/