linux-kernel - Re: [RFC PATCH 6/7] locking/rtqspinlock: Voluntarily yield CPU when need

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Message-ID: <423f5394-e1a1-06b5-8bb0-c9f77945dbdb@redhat.com>
Date:   Thu, 5 Jan 2017 11:16:42 +0100
From:   Daniel Bristot de Oliveira <bristot@...hat.com>
To:     Waiman Long <longman@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        "H. Peter Anvin" <hpa@...or.com>
Cc:     linux-kernel@...r.kernel.org
Subject: Re: [RFC PATCH 6/7] locking/rtqspinlock: Voluntarily yield CPU when
 need_sched()

On 01/03/2017 07:00 PM, Waiman Long wrote:
>  For nested spinlock with outer lock acquired, it will
> + * boost its priority to the highest RT priority level to try to acquire the
> + * inner lock, finish up its work, release the locks and reenable preemption.

DL scheduler turns the definition of "highest RT priority" more
complicated. One may try to move a task to the DL class with a very
closer deadline, but a DL task can always be rejected by the admission
test....

-- Daniel