From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751713AbaCGE0m (ORCPT ); Thu, 6 Mar 2014 23:26:42 -0500 Received: from mail-ea0-f174.google.com ([209.85.215.174]:62224 "EHLO mail-ea0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750908AbaCGE0k (ORCPT ); Thu, 6 Mar 2014 23:26:40 -0500 Message-ID: <1394166397.5056.40.camel@marge.simpson.net> Subject: Re: [PATCH] net: sched: dev_deactivate_many(): use msleep(1) instead of yield() to wait for outstanding qdisc_run calls From: Mike Galbraith To: David Miller Cc: mkl@pengutronix.de, linux-rt-users@vger.kernel.org, linux-kernel@vger.kernel.org, netdev@vger.kernel.org, kernel@pengutronix.de Date: Fri, 07 Mar 2014 05:26:37 +0100 In-Reply-To: <20140306.160622.59358366688518505.davem@davemloft.net> References: <1393976987-23555-1-git-send-email-mkl@pengutronix.de> <20140306.160622.59358366688518505.davem@davemloft.net> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.2.3 Content-Transfer-Encoding: 7bit Mime-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 2014-03-06 at 16:06 -0500, David Miller wrote: > From: Marc Kleine-Budde > Date: Wed, 5 Mar 2014 00:49:47 +0100 > > > @@ -839,7 +839,7 @@ void dev_deactivate_many(struct list_head *head) > > /* Wait for outstanding qdisc_run calls. */ > > list_for_each_entry(dev, head, unreg_list) > > while (some_qdisc_is_busy(dev)) > > - yield(); > > + msleep(1) > > } > > I don't understand this. > > yield() should really _mean_ yield. It does, but yield() semantics make it useless for what you want to do.. and pretty much undefined for anything other than SCHED_FIFO. If you really want to give up the CPU to any old body, you have to sleep. -Mike