Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
Date:   Tue, 11 Sep 2018 12:21:22 -0700
From:   Davidlohr Bueso <dave@stgolabs.net>
To:     Peter Zijlstra <peterz@infradead.org>
Cc:     Waiman Long <longman@redhat.com>, Ingo Molnar <mingo@redhat.com>,
        Will Deacon <will.deacon@arm.com>, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] locking/rwsem: Make owner store task pointer of last
 owning reader
Message-ID: <20180911192122.GD3902@linux-r8p5>
References: <1536265114-10842-1-git-send-email-longman@redhat.com>
 <20180910093156.GS24082@hirez.programming.kicks-ass.net>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii; format=flowed
Content-Disposition: inline
In-Reply-To: <20180910093156.GS24082@hirez.programming.kicks-ass.net>
User-Agent: Mutt/1.10.1 (2018-07-13)
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On Mon, 10 Sep 2018, Peter Zijlstra wrote:

>[ RT has something along those lines, and I have half a patch that
>  starts doing that too, but I never found enough time to really work on
>  it :-( ]

But don't rt rwsems act pretty much like a regular mutex in that it only
allows readers to nest, not share the lock because of priority inversion
scenarios.

Also, wrt rtmutex, will that top-spinner thing ever make it in?

Thanks,
Davidlohr