From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tejun Heo Subject: Re: [PATCH 2.6.22] Add LED trigger to libata core Date: Mon, 19 Mar 2007 21:14:14 +0900 Message-ID: <45FE7E96.4050808@gmail.com> References: <20070318170605.3751D5B80F1@ganymede.vroon.org> <45FE14BD.5090701@gmail.com> <20070319124616.2fb7494b@lxorguk.ukuu.org.uk> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from nz-out-0506.google.com ([64.233.162.226]:6666 "EHLO nz-out-0506.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753815AbXCSMOV (ORCPT ); Mon, 19 Mar 2007 08:14:21 -0400 Received: by nz-out-0506.google.com with SMTP id s1so611550nze for ; Mon, 19 Mar 2007 05:14:21 -0700 (PDT) In-Reply-To: <20070319124616.2fb7494b@lxorguk.ukuu.org.uk> Sender: linux-ide-owner@vger.kernel.org List-Id: linux-ide@vger.kernel.org To: Alan Cox Cc: Tony Vroon , Jeff Garzik , linux-ide@vger.kernel.org, linux-kernel@vger.kernel.org Alan Cox wrote: > On Mon, 19 Mar 2007 13:42:37 +0900 > Tejun Heo wrote: > >> Tony Vroon wrote: >>> This duplicates the IDE core LED trigger in the libata core. >>> I plan to use this by allowing PMU LED control on G5 towers. My test platform >>> is a PowerMac 7,3 (Dual G5 2.0GHz, June 2004) with a K2 (sata_svw) controller. >> I think this fits better in libata-core.c::ata_qc_issue(). Can you move >> it to there? > > Gak. I'd rather it stayed out of ata_qc_issue() which is a critical path > for performance. The original place is in the critical path too. It's just at the outer function which eventually calls ata_qc_issue() (the mapping is almost one to one). > Our command issu is already too heavy and not all > controllers have queueing to absorb that. How many controllers actually > need this hook and can we not have ata_qc_issue_with_led() helpers for > them ? Our issue path is somewhat expensive due to SCSI -> ATA translation but I don't think it really matters on any modern cpu. It can definitely hurt on embedded tho. :-( -- tejun