From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932601AbeARPVs (ORCPT ); Thu, 18 Jan 2018 10:21:48 -0500 Received: from mail.kernel.org ([198.145.29.99]:44004 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932124AbeARPVq (ORCPT ); Thu, 18 Jan 2018 10:21:46 -0500 DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org E1E7020C0F Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=goodmis.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=rostedt@goodmis.org Date: Thu, 18 Jan 2018 10:21:39 -0500 From: Steven Rostedt To: Byungchul Park Cc: Petr Mladek , Sergey Senozhatsky , akpm@linux-foundation.org, linux-mm@kvack.org, Cong Wang , Dave Hansen , Johannes Weiner , Mel Gorman , Michal Hocko , Vlastimil Babka , Peter Zijlstra , Linus Torvalds , Jan Kara , Mathieu Desnoyers , Tetsuo Handa , rostedt@rostedt.homelinux.com, Sergey Senozhatsky , Tejun Heo , Pavel Machek , linux-kernel@vger.kernel.org, kernel-team@lge.com Subject: Re: [PATCH v5 1/2] printk: Add console owner and waiter logic to load balance console writes Message-ID: <20180118102139.43c04de5@gandalf.local.home> In-Reply-To: <171cf5b9-2cb6-8e70-87f5-44ace35c2ce4@lge.com> References: <20180110132418.7080-1-pmladek@suse.com> <20180110132418.7080-2-pmladek@suse.com> <20180117120446.44ewafav7epaibde@pathway.suse.cz> <4a24ce1d-a606-3add-ec30-91ce9a1a1281@lge.com> <20180117211953.2403d189@vmware.local.home> <171cf5b9-2cb6-8e70-87f5-44ace35c2ce4@lge.com> X-Mailer: Claws Mail 3.14.0 (GTK+ 2.24.31; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 18 Jan 2018 13:01:46 +0900 Byungchul Park wrote: > > I disagree. It is like a spinlock. You can say a spinlock() that is > > blocked is also waiting for an event. That event being the owner does a > > spin_unlock(). > > That's exactly what I was saying. Excuse me but, I don't understand > what you want to say. Could you explain more? What do you disagree? I guess I'm confused at what you are asking for then. > > I find your way confusing. I'm simulating a spinlock not a wait for > > completion. A wait for completion usually initiates something then > > I used the word, *event* instead of *completion*. wait_for_completion() > and complete() are just an example of a pair of waiter and event. > Lock and unlock can also be another example, too. > > Important thing is that who waits and who triggers the event. Using the > pair, we can achieve various things, for examples: > > 1. Synchronization like wait_for_completion() does. > 2. Control exclusively entering into a critical area. > 3. Whatever. > > > waits for it to complete. This is trying to get into a critical area > > but another task is currently in it. It's simulating a spinlock as far > > as I can see. > > Anyway it's an example of "waiter for an event, and the event". > > JFYI, spinning or sleeping does not matter. Those are just methods to > achieve a wait. I know you're not talking about this though. It's JFYI. OK, if it is just FYI. -- Steve