From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753486AbbERNFU (ORCPT ); Mon, 18 May 2015 09:05:20 -0400 Received: from mail2.unitn.it ([193.205.194.22]:51330 "EHLO mail2.unitn.it" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752659AbbERNEx (ORCPT ); Mon, 18 May 2015 09:04:53 -0400 From: Luca Abeni To: peterz@infradead.org Cc: henrik@austad.us, juri.lelli@gmail.com, raistlin@linux.it, mingo@kernel.org, linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, Luca Abeni Subject: [PATCH 8/9] Documentation/scheduler/sched-deadline.txt: relationship between tasks' deadlines and scheduling deadlines Date: Mon, 18 May 2015 15:00:31 +0200 Message-Id: <1431954032-16473-9-git-send-email-luca.abeni@unitn.it> X-Mailer: git-send-email 1.7.9.5 In-Reply-To: <1431954032-16473-1-git-send-email-luca.abeni@unitn.it> References: <1431954032-16473-1-git-send-email-luca.abeni@unitn.it> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Clarify what is the relationship between tasks' parameters and scheduling parameters, explaining how to set the scheduling parameters so that all the absolute deadlines of a task are respected. Signed-off-by: Luca Abeni --- Documentation/scheduler/sched-deadline.txt | 14 +++++++++++--- 1 file changed, 11 insertions(+), 3 deletions(-) diff --git a/Documentation/scheduler/sched-deadline.txt b/Documentation/scheduler/sched-deadline.txt index bd9ce00..ead13bcc 100644 --- a/Documentation/scheduler/sched-deadline.txt +++ b/Documentation/scheduler/sched-deadline.txt @@ -249,9 +249,17 @@ CONTENTS the total utilization is smaller or equal than M then the response times of the tasks are limited. - SCHED_DEADLINE can be used to schedule real-time tasks guaranteeing that - the jobs' deadlines of a task are respected. In order to do this, a task - must be scheduled by setting: + Finally, it is important to understand the relationship between the + SCHED_DEADLINE scheduling parameters described in Section 2 (runtime, + deadline and period) and the real-time task parameters (WCET, D, P) + described in this section. Note that the tasks' temporal constraints are + represented by its absolute deadlines d_j = r_j + D described above, while + SCHED_DEADLINE schedules the tasks according to scheduling deadlines (see + Section 2). + If an admission test is used to guarantee that the scheduling deadlines + are respected, then SCHED_DEADLINE can be used to schedule real-time tasks + guaranteeing that all the jobs' deadlines of a task are respected. + In order to do this, a task must be scheduled by setting: - runtime >= WCET - deadline = D -- 1.7.9.5