From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <linux-kernel-owner@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
        id S1428216AbdDXUny (ORCPT <rfc822;w@1wt.eu>);
        Mon, 24 Apr 2017 16:43:54 -0400
Received: from mail-wm0-f54.google.com ([74.125.82.54]:34130 "EHLO
        mail-wm0-f54.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org
        with ESMTP id S977800AbdDXUns (ORCPT
        <rfc822;linux-kernel@vger.kernel.org>);
        Mon, 24 Apr 2017 16:43:48 -0400
Subject: Re: [PATCH RFC] sched/deadline: Use the revised wakeup rule for
 suspending constrained dl tasks
From: Daniel Bristot de Oliveira <bristot@redhat.com>
To: Ingo Molnar <mingo@redhat.com>, Peter Zijlstra <peterz@infradead.org>
Cc: Xunlei Pang <xpang@redhat.com>, Juri Lelli <juri.lelli@arm.com>,
        Steven Rostedt <rostedt@goodmis.org>,
        Luca Abeni <luca.abeni@santannapisa.it>,
        Tommaso Cucinotta <tommaso.cucinotta@sssup.it>,
        Romulo Silva de Oliveira <romulo.deoliveira@ufsc.br>,
        linux-kernel@vger.kernel.org
References: <5c6933890ea6daa3b4edb4983b0c6f094ad3903d.1493045834.git.bristot@redhat.com>
Message-ID: <f6d97aba-9b28-fb59-749f-7b9adf276700@redhat.com>
Date: Mon, 24 Apr 2017 22:43:45 +0200
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101
 Thunderbird/52.0
MIME-Version: 1.0
In-Reply-To: <5c6933890ea6daa3b4edb4983b0c6f094ad3903d.1493045834.git.bristot@redhat.com>
Content-Type: text/plain; charset=utf-8
Content-Language: en-US
Content-Transfer-Encoding: 7bit
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

On 04/24/2017 05:18 PM, Daniel Bristot de Oliveira wrote:
>   remaining runtime = 4
>   laxity = 5
Oops! The laxity is 5... so...

> Knowing the laxity of a task (deadline - t), it is possible to move
> it to the other side of the equality, thus enabling to define max
> remaining runtime a task can use within the absolute deadline, without
> over-running the allowed density:
> 
>   runtime = (dl_runtime / dl_deadline) * (deadline - t)
> 
> For instance, in our previous example, the task could still run:
> 
>   runtime = ( 5 / 7 ) * 4
>   runtime = 2.85 ms

This should be:
    runtime = ( 5 / 7 ) * 5
    runtime = 3.57 ms

even better :-)

-- Daniel