From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754893AbeDCHnJ (ORCPT ); Tue, 3 Apr 2018 03:43:09 -0400 Received: from mail-wm0-f66.google.com ([74.125.82.66]:39115 "EHLO mail-wm0-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751454AbeDCHnH (ORCPT ); Tue, 3 Apr 2018 03:43:07 -0400 X-Google-Smtp-Source: AIpwx4+qY6UMorzBgs8fs6v6fCE2eq9hXEq3GhkQgFKM4h9AaHZeuY4A6fcbAcar8OXAVycznDK1KA== From: Claudio Scordino To: Peter Zijlstra , Ingo Molnar , Jonathan Corbet Cc: Claudio Scordino , Juri Lelli , Luca Abeni , linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org Subject: [PATCH] sched/deadline: add overrun signal and GRUB-PA in the documentation Date: Tue, 3 Apr 2018 09:42:42 +0200 Message-Id: <1522741362-4542-1-git-send-email-claudio@evidence.eu.com> X-Mailer: git-send-email 2.7.4 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Signed-off-by: Claudio Scordino CC: Juri Lelli CC: Luca Abeni CC: linux-kernel@vger.kernel.org CC: linux-doc@vger.kernel.org --- Documentation/scheduler/sched-deadline.txt | 25 ++++++++++++++++++++++++- 1 file changed, 24 insertions(+), 1 deletion(-) diff --git a/Documentation/scheduler/sched-deadline.txt b/Documentation/scheduler/sched-deadline.txt index 8ce78f8..b14e03f 100644 --- a/Documentation/scheduler/sched-deadline.txt +++ b/Documentation/scheduler/sched-deadline.txt @@ -49,7 +49,7 @@ CONTENTS 2.1 Main algorithm ------------------ - SCHED_DEADLINE uses three parameters, named "runtime", "period", and + SCHED_DEADLINE [18] uses three parameters, named "runtime", "period", and "deadline", to schedule tasks. A SCHED_DEADLINE task should receive "runtime" microseconds of execution time every "period" microseconds, and these "runtime" microseconds are available within "deadline" microseconds @@ -117,6 +117,10 @@ CONTENTS scheduling deadline = scheduling deadline + period remaining runtime = remaining runtime + runtime + The SCHED_FLAG_DL_OVERRUN flag in sched_attr's sched_flags field allows a task + to get informed about runtime overruns through the delivery of SIGXCPU + signals. + 2.2 Bandwidth reclaiming ------------------------ @@ -279,6 +283,19 @@ CONTENTS running_bw is incremented. +2.3 Energy-aware scheduling +------------------------ + + When cpufreq's schedutil governor is selected, SCHED_DEADLINE implements the + GRUB-PA [19] algorithm, reducing the CPU operating frequency to the minimum + value that still allows to meet the deadlines. This behavior is currently + implemented only for ARM architectures. + + A particular care must be taken in case the time needed for changing frequency + is of the same order of magnitude of the reservation period. In such cases, + setting a fixed CPU frequency results in a lower amount of deadline misses. + + 3. Scheduling Real-Time Tasks ============================= @@ -505,6 +522,12 @@ CONTENTS 17 - L. Abeni, G. Lipari, A. Parri, Y. Sun, Multicore CPU reclaiming: parallel or sequential?. In Proceedings of the 31st Annual ACM Symposium on Applied Computing, 2016. + 18 - J. Lelli, C. Scordino, L. Abeni, D. Faggioli, Deadline scheduling in the + Linux kernel, Software: Practice and Experience, 46(6): 821-839, June + 2016. + 19 - C. Scordino, L. Abeni, J. Lelli, Energy-Aware Real-Time Scheduling in + the Linux Kernel, 33rd ACM/SIGAPP Symposium On Applied Computing (SAC + 2018), Pau, France, April 2018. 4. Bandwidth management -- 2.7.4