From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tejun Heo Subject: Re: ahci: CAP_SSS and parallel scan Date: Thu, 06 May 2010 16:44:38 +0200 Message-ID: <4BE2D5D6.1010705@kernel.org> References: <4BE27C49.5090809@kernel.org> <4BE28C4F.9000903@linux.intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Return-path: Received: from hera.kernel.org ([140.211.167.34]:51160 "EHLO hera.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753071Ab0EFOpH (ORCPT ); Thu, 6 May 2010 10:45:07 -0400 In-Reply-To: <4BE28C4F.9000903@linux.intel.com> Sender: linux-ide-owner@vger.kernel.org List-Id: linux-ide@vger.kernel.org To: Arjan van de Ven Cc: Jeff Garzik , t.artem@mailcity.com, "linux-ide@vger.kernel.org" Hello, On 05/06/2010 11:30 AM, Arjan van de Ven wrote: > The thing is, SSS means the system requests (well, demands) that we > don't spin up the disks up in parallel.... which we really really > ought to honor... Jeff had a very valid point. Hmmm... yeah but SSS doesn't really demand it. It just says "I can do staggered spin up". I wish this thing had been implemented in the form of "stay spin down till necessary (ie. start in standby mode)". Currently, there's no way to tell whether staggered spin up is needed or drives are already spun up. > While today some bioses may spin everything up, that's not going to > be the case going forward... the industry as a whole is moving away > from that (slowly but steadily). Yeah, sure, in the long run maybe but I'm skeptical how useful this is at this point. Going forward, the right thing to do would be implementing some sort of token infrastructure so that drivers can request and hold the token while spinning up a drive so that the concurrency of spin ups can be controlled. Jeff, what do you think about lifting the check for now unless there are known cases where this can cause problems? Thanks. -- tejun