From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jeff Garzik Subject: Re: Per ATA host sysfs attributes? Date: Tue, 10 Mar 2009 19:07:42 -0400 Message-ID: <49B6F2BE.3000509@pobox.com> References: <49B6C99B.9030507@rtr.ca> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from srv5.dvmed.net ([207.36.208.214]:54320 "EHLO mail.dvmed.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752427AbZCJXHt (ORCPT ); Tue, 10 Mar 2009 19:07:49 -0400 In-Reply-To: <49B6C99B.9030507@rtr.ca> Sender: linux-ide-owner@vger.kernel.org List-Id: linux-ide@vger.kernel.org To: Mark Lord Cc: IDE/ATA development list , Tejun Heo , Alan Cox Mark Lord wrote: > Guys, > > I have added IRQ coalescing to sata_mv, but need a way to activate/tune it. > There are two simple parameters: an IRQ count threshold, and a time > threshold. > > Whenever either the count or the time threshold is exceeded, > the chip will generate an interrupt (assuming at least one completed > event). > > These two parameters are per-chip (actually, per group of four ports > within the chip). > How can I export these for setting/query withing sysfs ? > > It is all rather easy to create per-SCSI-host attrs in sysfs, > but I don't see any obvious way to do it per-chip. > Suggestions? The absence of a kobject associated with ata_host is largely the root cause of this problem you've noted. Long term, we want to move in a direction where we have a "storage_host" container object, containing one or more port-style objects that can be ATA or SCSI. In that scenario (and what we want to move towards, over the years), the sysfs attachment points should be fairly obvious. Lacking a better suggestion, I suppose the answer is exporting per-chip variables multiple times, once per scsi-host. Just get the locking right, since multiple sysfs attributes access the same underlying per-chip variable. > For now, I'm doing it with a module parameter, > but that's really rather stone-age in the sysfs era. Indeed! :) Jeff