From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932707AbdIRPLJ (ORCPT ); Mon, 18 Sep 2017 11:11:09 -0400 Received: from mail.kernel.org ([198.145.29.99]:46104 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932478AbdIRPLI (ORCPT ); Mon, 18 Sep 2017 11:11:08 -0400 DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org B386721A2A 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: Mon, 18 Sep 2017 11:11:05 -0400 From: Steven Rostedt To: Neeraj Upadhyay Cc: 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, peterz@infradead.org Subject: Re: Query regarding synchronize_sched_expedited and resched_cpu Message-ID: <20170918111105.15f687da@gandalf.local.home> In-Reply-To: References: <8f33e48e-ac6d-2c88-e16f-20b698c06292@codeaurora.org> <20170917010015.GW3521@linux.vnet.ibm.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 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. -- Steve