From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tejun Heo Subject: Re: [PATCH] Asynchronous scan support for libata Date: Sat, 08 Sep 2007 17:10:27 +0900 Message-ID: <46E258F3.20805@gmail.com> References: <20070906210505.GF27404@parisc-linux.org> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: Received: from wa-out-1112.google.com ([209.85.146.179]:40891 "EHLO wa-out-1112.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754152AbXIHRIK (ORCPT ); Sat, 8 Sep 2007 13:08:10 -0400 Received: by wa-out-1112.google.com with SMTP id v27so940147wah for ; Sat, 08 Sep 2007 10:08:10 -0700 (PDT) In-Reply-To: <20070906210505.GF27404@parisc-linux.org> Sender: linux-ide-owner@vger.kernel.org List-Id: linux-ide@vger.kernel.org To: Matthew Wilcox Cc: Jeff Garzik , linux-ide@vger.kernel.org Matthew Wilcox wrote: > Last December, I posted this: http://lwn.net/Articles/213635/ > > Here's an updated version. It shaves 5 seconds off boot time on my > configuration (qla2xxx, emulex, two ata_piix, dual fusion), but could > save more or less on other setups. > > I think I can remove the 'sync' argument and code from > ata_scsi_scan_host() now, but wanted to send out this update today. > > --- > > Some of the drivers (AHCI was mentioned to me as a culprit) take a long > time to discover all the devices attached to them. Even for ones which > are relatively quick, if you put a lot of them in a machine, it will > take a long time in aggregate. This can be fixed by adding support for > asynchronous scsi scans, which causes the time-consuming portions of > initialisation to take place in threads. > > Signed-off-by: Matthew Wilcox I think it's generally okay although it would need to spend quite some time in -mm and we'll need to exclude several drivers which require host-wide silence for mode programming (the current code is buggy but sequential probing hides it pretty well) till host-wide exclusion is implemented. Thanks. -- tejun