Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752676Ab3GNOdu (ORCPT ); Sun, 14 Jul 2013 10:33:50 -0400 Received: from youngberry.canonical.com ([91.189.89.112]:33655 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752521Ab3GNOdr (ORCPT ); Sun, 14 Jul 2013 10:33:47 -0400 MIME-Version: 1.0 In-Reply-To: <1373807844.4998.10.camel@palomino.walls.org> References: <1373533573-12272-1-git-send-email-ming.lei@canonical.com> <1373807844.4998.10.camel@palomino.walls.org> Date: Sun, 14 Jul 2013 22:33:44 +0800 Message-ID: Subject: Re: [PATCH 00/50] USB: cleanup spin_lock in URB->complete() From: Ming Lei To: Andy Walls Cc: Greg Kroah-Hartman , linux-usb@vger.kernel.org, Oliver Neukum , Alan Stern , linux-input@vger.kernel.org, linux-bluetooth@vger.kernel.org, netdev@vger.kernel.org, linux-wireless@vger.kernel.org, linux-media@vger.kernel.org, alsa-devel@alsa-project.org, linux-kernel@vger.kernel.org Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1248 Lines: 40 On Sun, Jul 14, 2013 at 9:17 PM, Andy Walls wrote: > On Thu, 2013-07-11 at 17:05 +0800, Ming Lei wrote: >> Hi, >> >> As we are going to run URB->complete() in tasklet context[1][2], > > Hi, > > Please pardon my naivete, but why was it decided to use tasklets to > defer work, as opposed to some other deferred work mechanism? > > It seems to me that getting rid of tasklets has been an objective for > years: > > http://lwn.net/Articles/239633/ > http://lwn.net/Articles/520076/ > http://lwn.net/Articles/240054/ We discussed the problem in the below link previously[1], Steven and Thomas suggested to use threaded irq handler, but which may degrade USB mass storage performance, so we have to take tasklet now until we rewrite transport part of USB mass storage driver. Also the conversion[2] has avoided the tasklet spin lock problem already. [1], http://marc.info/?t=137079119200001&r=1&w=2 [2], http://marc.info/?l=linux-usb&m=137286326726326&w=2 Thanks, -- Ming Lei -- 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/