From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753240AbaHMOoT (ORCPT ); Wed, 13 Aug 2014 10:44:19 -0400 Received: from bombadil.infradead.org ([198.137.202.9]:55025 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753100AbaHMOoO (ORCPT ); Wed, 13 Aug 2014 10:44:14 -0400 Date: Wed, 13 Aug 2014 16:43:42 +0200 From: Peter Zijlstra To: Steven Rostedt Cc: "Paul E. McKenney" , 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, dhowells@redhat.com, edumazet@google.com, dvhart@linux.intel.com, fweisbec@gmail.com, oleg@redhat.com, bobby.prani@gmail.com Subject: Re: [PATCH v5 tip/core/rcu 15/16] rcu: Make RCU-tasks wait for idle tasks Message-ID: <20140813144342.GR9918@twins.programming.kicks-ass.net> References: <20140811224840.GA25594@linux.vnet.ibm.com> <1407797345-28227-1-git-send-email-paulmck@linux.vnet.ibm.com> <1407797345-28227-15-git-send-email-paulmck@linux.vnet.ibm.com> <20140813081215.GB9918@twins.programming.kicks-ass.net> <20140813124818.GQ4752@linux.vnet.ibm.com> <20140813134025.GN9918@twins.programming.kicks-ass.net> <20140813095132.56d288f2@gandalf.local.home> <20140813140705.GO9918@twins.programming.kicks-ass.net> <20140813101301.08019895@gandalf.local.home> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="tXjKu8zC63dF7Z1t" Content-Disposition: inline In-Reply-To: <20140813101301.08019895@gandalf.local.home> User-Agent: Mutt/1.5.21 (2012-12-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --tXjKu8zC63dF7Z1t Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Wed, Aug 13, 2014 at 10:13:01AM -0400, Steven Rostedt wrote: > On Wed, 13 Aug 2014 16:07:05 +0200 > Peter Zijlstra wrote: >=20 > > On Wed, Aug 13, 2014 at 09:51:32AM -0400, Steven Rostedt wrote: > >=20 > > > I still need to look at the patches, but if this is just for the idle > > > case, then we don't need it. The idle case can be solved with a simple > > > sched_on_each_cpu(). I need a way to solve waiting for processes to > > > finish from a preemption point. > > >=20 > > > That's all I want, and if we can remove the "idle" case and document = it > > > well that it's not covered and a sched_on_each_cpu() may be needed, > > > then I'm fine with that. > > >=20 > > > sched_on_each_cpu(dummy_op); > > > call_rcu_tasks(free_tramp); > >=20 > > Sure, but why not dtrt and push rcu_idle hooks all the way down into the > > idle drivers if and where appropriate? > >=20 > > There isn't _that_ much idle driver code. Also, some stuff should be > > cleaned up; we're already calling stop_critical_timings() in the generic > > idle code, and then calling it again in the cpuidle drivers. > >=20 > >=20 >=20 > True, perhaps the rcu code should hook into the stop_critical_timings > code? Not sure; the current proposal would have rcu_idle code be far narrower than the critical_timings thing, not sure if that's an accident or desired. If they have similar requirements we could indeed merge them. --tXjKu8zC63dF7Z1t Content-Type: application/pgp-signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.12 (GNU/Linux) iQIcBAEBAgAGBQJT63meAAoJEHZH4aRLwOS6smgP/3Z21aUJSyOxfcVA+64XWEvx Dy7mBk3KCyrbVBtLEGuwXwck6c853QMKk6Yb8Y8o+zvCOABS4bPMVXAcEOEcuQTj ZNv355vVq+sc62XtRqsTX3sfEZHp+XkWrYgCAT1vbRdvIr5NqqzBvVcRB3s+ctXZ xldsCoJUxRFCceS6qReoqzFbcvmoX8mV/MYv56Qvueg3FcS3Ly+bIeU3elGrt20T qdGPGXqn0ZqaWF6UgEKpX3A4CxthkxO+EroAGFoTPh2mUWQIVjBeZ5IbQu+EDQIq 99IjMde18HS5XhioO2K3DKrll3E3j4Rv4QNQMn6hEXzHiyyzlRFartynb8dm4Lii gFPjO5ybFnOc+O/7hq4I4p7a4ygOCkGn2qiVe2rsqWQ4HlgdngYk0c8BtRGatpJ2 P7NC/L+izo+Ag0uThSDDyjQFHd4yx+a8aZc0qxj0evfKourqoIkk9xM9SjD73Giu XE8PofcVGcM21w0IeSIfNE6MoFFEAffa1sUfQ9OnG0ULjSqu95g/GDBf2GeYhZAU 7X5sMD/tA4TKwH9zistvAGWuvh8I/uXcC4UVAOC1PSk636iG+GDMbZmIDxTPFgbD xSF5mt/9bwhdq9qwDNGf8CxB2VoS0W07pSxdfT+xRBsItCVEyRcu9oCZp0eReKWJ AwKKBKIOuVC0N6wypq42 =xmb7 -----END PGP SIGNATURE----- --tXjKu8zC63dF7Z1t--