Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756366AbaFWQpi (ORCPT ); Mon, 23 Jun 2014 12:45:38 -0400 Received: from e39.co.us.ibm.com ([32.97.110.160]:45493 "EHLO e39.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756336AbaFWQpf (ORCPT ); Mon, 23 Jun 2014 12:45:35 -0400 Date: Mon, 23 Jun 2014 09:45:29 -0700 From: "Paul E. McKenney" To: Christoph Lameter Cc: Peter Zijlstra , linux-kernel@vger.kernel.org, mingo@kernel.org, laijs@cn.fujitsu.com, dipankar@in.ibm.com, akpm@linux-foundation.org, mathieu.desnoyers@efficios.com, josh@joshtriplett.org, tglx@linutronix.de, rostedt@goodmis.org, dhowells@redhat.com, edumazet@google.com, dvhart@linux.intel.com, fweisbec@gmail.com, oleg@redhat.com, dave.hansen@intel.com, ak@linux.intel.com, umgwanakikbuti@gmail.com Subject: Re: [PATCH tip/core/rcu] Reduce overhead of cond_resched() checks for RCU Message-ID: <20140623164529.GE4603@linux.vnet.ibm.com> Reply-To: paulmck@linux.vnet.ibm.com References: <20140621025958.GA7185@linux.vnet.ibm.com> <20140623062615.GB19860@laptop.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.21 (2010-09-15) X-TM-AS-MML: disable X-Content-Scanned: Fidelis XPS MAILER x-cbid: 14062316-9332-0000-0000-0000012C5141 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Jun 23, 2014 at 08:51:08AM -0500, Christoph Lameter wrote: > On Mon, 23 Jun 2014, Peter Zijlstra wrote: > > > On the topic of these threads; I recently noticed RCU grew a metric ton > > of them, I found some 75 rcu kthreads on my box, wth up with that? > > Would kworker threads work for rcu? That would also avoid the shifting > around of RCU threads for NOHZ configurations (which seems to have to be > done manually right now). The kworker subsystem work that allows > restriction to non NOHZ hardware threads would then also allow the > shifting of the rcu threads which would simplify the whole endeavor. Short term, I am planning to use a different method to automate the binding of the rcuo kthreads to housekeeping CPUs, but longer term, it might well make a lot of sense to move to workqueues and the kworker threads. Thanx, Paul -- 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/