From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752548Ab1ADRIE (ORCPT ); Tue, 4 Jan 2011 12:08:04 -0500 Received: from casper.infradead.org ([85.118.1.10]:58155 "EHLO casper.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752075Ab1ADRIC convert rfc822-to-8bit (ORCPT ); Tue, 4 Jan 2011 12:08:02 -0500 Subject: Re: [RFC -v3 PATCH 2/3] sched: add yield_to function From: Peter Zijlstra To: Hillf Danton Cc: Rik van Riel , kvm@vger.kernel.org, linux-kernel@vger.kernel.org, Avi Kiviti , Srivatsa Vaddagiri , Mike Galbraith , Chris Wright In-Reply-To: References: <20110103162637.29f23c40@annuminas.surriel.com> <20110103162918.577a9620@annuminas.surriel.com> <4D234E60.3010804@redhat.com> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8BIT Date: Tue, 04 Jan 2011 18:08:10 +0100 Message-ID: <1294160890.2016.171.camel@laptop> Mime-Version: 1.0 X-Mailer: Evolution 2.30.3 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 2011-01-05 at 00:51 +0800, Hillf Danton wrote: > Where is the yield_to callback in the patch for RT schedule class? > If @p is RT, what could you do? RT guests are a pipe dream, you first need to get the hypervisor (kvm in this case) to be RT, which it isn't. Then you either need to very statically set-up the host and the guest scheduling constraints (not possible with RR/FIFO) or have a complete paravirt RT scheduler which communicates its requirements to the host.