From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751785AbdIUPqq (ORCPT ); Thu, 21 Sep 2017 11:46:46 -0400 Received: from mail.kernel.org ([198.145.29.99]:60456 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751740AbdIUPqo (ORCPT ); Thu, 21 Sep 2017 11:46:44 -0400 DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 644E02170D 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, 21 Sep 2017 11:46:40 -0400 From: Steven Rostedt To: Peter Zijlstra Cc: Neeraj Upadhyay , paulmck@linux.vnet.ibm.com, josh@joshtriplett.org, mathieu.desnoyers@efficios.com, jiangshanlai@gmail.com, linux-kernel@vger.kernel.org, sramana@codeaurora.org, prsood@codeaurora.org, pkondeti@codeaurora.org, markivx@codeaurora.org Subject: Re: Query regarding synchronize_sched_expedited and resched_cpu Message-ID: <20170921114640.6c9920a5@gandalf.local.home> In-Reply-To: <20170921135546.x3q3zeicbo2vtjvk@hirez.programming.kicks-ass.net> References: <8f33e48e-ac6d-2c88-e16f-20b698c06292@codeaurora.org> <20170917010015.GW3521@linux.vnet.ibm.com> <20170918111105.15f687da@gandalf.local.home> <20170921135546.x3q3zeicbo2vtjvk@hirez.programming.kicks-ass.net> 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, 21 Sep 2017 15:55:46 +0200 Peter Zijlstra wrote: > On Mon, Sep 18, 2017 at 11:11:05AM -0400, Steven Rostedt wrote: > > On Sun, 17 Sep 2017 11:37:06 +0530 > > Neeraj Upadhyay wrote: > > > > > Hi Paul, how about replacing raw_spin_trylock_irqsave with > > > raw_spin_lock_irqsave in resched_cpu()? Are there any paths > > > in RCU code, which depend on trylock check/spinlock recursion? > > > > It looks to me that resched_cpu() was added for nohz full sched > > balancing, but is not longer used by that. The only user is currently > > RCU. Perhaps we should change that from a trylock to a lock. > > No, regular NOHZ balancing. NOHZ FULL wasn't conceived back then. > > 46cb4b7c88fa ("sched: dynticks idle load balancing") Bah, every time I type NOHZ today I add FULL after it. I did mean NOHZ without FULL. :-p -- Steve