From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934501AbdEVTCQ (ORCPT ); Mon, 22 May 2017 15:02:16 -0400 Received: from Galois.linutronix.de ([146.0.238.70]:49951 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1760944AbdEVTCP (ORCPT ); Mon, 22 May 2017 15:02:15 -0400 Date: Mon, 22 May 2017 21:02:12 +0200 (CEST) From: Thomas Gleixner To: =?ISO-8859-15?Q?Fredrik_Markstr=F6m?= cc: linux-kernel@vger.kernel.org Subject: Re: Core isolation, cpu hotplug and stop_machine In-Reply-To: Message-ID: References: User-Agent: Alpine 2.20 (DEB 67 2015-01-07) MIME-Version: 1.0 Content-Type: multipart/mixed; BOUNDARY="8323329-1465821860-1495479733=:2407" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org This message is in MIME format. The first part should be readable text, while the remaining parts are likely unreadable without MIME-aware tools. --8323329-1465821860-1495479733=:2407 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8BIT On Mon, 22 May 2017, Fredrik Markström wrote: > So is there any ongoing work to solve this problem and what is the > preferred way to solve it, is it: > > 1) stop_machine() free hotplug. It seems to be quite complex but > probably solves more problems > then the one above. Yes, but it's a non-trivial problem. I looked into it not too long ago and it just refuses to fall in place due to circular dependencies. It's on my todo list, but certainly not on the top. And aside of that cpu hotplug is a vehicle and not a solution. > 2) Invent some new mechanism/interface separate from hotplug to > migrate timers and hrtimers. There is ongoing work to make this nonsensical timer placement stuff sane. It's buggy atm, but we are working on a fix. We have a similar plan for hrtimers. https://marc.info/?i=20170418111102.490432548%40linutronix.de > 3) Don't, because this isn't a use-case that linux should support. Well, we want full isolation to work, but we want proper solutions for it. Thanks, tglx --8323329-1465821860-1495479733=:2407--