Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
Date:   Wed, 19 Jan 2022 09:51:57 +0100
From:   Peter Zijlstra <peterz@infradead.org>
To:     Peter Oskolkov <posk@google.com>
Cc:     Peter Oskolkov <posk@posk.io>, mingo@redhat.com,
        tglx@linutronix.de, juri.lelli@redhat.com,
        vincent.guittot@linaro.org, dietmar.eggemann@arm.com,
        rostedt@goodmis.org, bsegall@google.com, mgorman@suse.de,
        bristot@redhat.com, linux-kernel@vger.kernel.org,
        linux-mm@kvack.org, linux-api@vger.kernel.org, x86@kernel.org,
        pjt@google.com, avagin@google.com, jannh@google.com,
        tdelisle@uwaterloo.ca
Subject: Re: [RFC][PATCH 3/3] sched: User Mode Concurency Groups
Message-ID: <YefRLYwKy0AeHyhz@hirez.programming.kicks-ass.net>
References: <20211214204445.665580974@infradead.org>
 <20211214205358.701701555@infradead.org>
 <20211221171900.GA580323@dev-hv>
 <YeGEM7TP3tekBVEh@hirez.programming.kicks-ass.net>
 <YeaRx9oDp08ABvyU@hirez.programming.kicks-ass.net>
 <CAPNVh5cdGiDqut90kUo-HXyya6Nbz_CjuUObYXfprgDhQHnUmg@mail.gmail.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <CAPNVh5cdGiDqut90kUo-HXyya6Nbz_CjuUObYXfprgDhQHnUmg@mail.gmail.com>
Precedence: bulk

On Tue, Jan 18, 2022 at 10:19:21AM -0800, Peter Oskolkov wrote:

> ================ worker timeouts
> 
> Timeouts now are easy to explain: mutex::lock() and condvar::wait() have
> timeouts, so workers waiting on these primitives naturally wait with timeouts;
> if sys_umcg_wait() supports worker timeouts, this is it, all is simple; if
> it does not, the userspace now has to implement the whole timeout machinery,
> in order to wake these sleeping workers when their timeouts expire.

I still have absolutely no idea what you're on about here. Please reply
to the email on that subject:

  https://lkml.kernel.org/r/Ya34S2JCQg+81h4t@hirez.programming.kicks-ass.net

What would you have the timeout actually do? Talk about the state
transitions.