Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::3:5 as permitted sender) client-ip=2620:137:e000::3:5;
Message-ID: <bdddc6f5-5e17-445b-bd86-dc14a8d17866@bytedance.com>
Date:   Wed, 11 Oct 2023 19:49:52 +0800
MIME-Version: 1.0
User-Agent: Mozilla Thunderbird
Subject: Re: Re: [PATCH 05/15] sched/fair: Implement an EEVDF like policy
Content-Language: en-US
To:     Peter Zijlstra <peterz@infradead.org>
Cc:     Benjamin Segall <bsegall@google.com>, mingo@kernel.org,
        vincent.guittot@linaro.org, linux-kernel@vger.kernel.org,
        juri.lelli@redhat.com, dietmar.eggemann@arm.com,
        rostedt@goodmis.org, mgorman@suse.de, bristot@redhat.com,
        corbet@lwn.net, qyousef@layalina.io, chris.hyser@oracle.com,
        patrick.bellasi@matbug.net, pjt@google.com, pavel@ucw.cz,
        qperret@google.com, tim.c.chen@linux.intel.com, joshdon@google.com,
        timj@gnu.org, kprateek.nayak@amd.com, yu.c.chen@intel.com,
        youssefesmat@chromium.org, joel@joelfernandes.org, efault@gmx.de,
        tglx@linutronix.de
References: <20230531115839.089944915@infradead.org>
 <20230531124603.931005524@infradead.org> <xm265y3sodyo.fsf@google.com>
 <a54a4ccb-9d56-4686-93b6-e9bbbe01f625@bytedance.com>
 <20231011073317.GJ14330@noisy.programming.kicks-ass.net>
From:   Abel Wu <wuyun.abel@bytedance.com>
In-Reply-To: <20231011073317.GJ14330@noisy.programming.kicks-ass.net>
Content-Type: text/plain; charset=UTF-8; format=flowed
Content-Transfer-Encoding: 7bit
Precedence: bulk

On 10/11/23 3:33 PM, Peter Zijlstra Wrote:
> On Wed, Oct 11, 2023 at 12:14:30PM +0800, Abel Wu wrote:
> 
>> there are cases worthy of breaking the 'eligible' rule.
> 
> See the discussion with Youssef, if we weaken the eligible rule you get
> horrific interference because you end up placing new tasks around the
> 0-lag point.

I have just begun studying the EEVDF scheduler, and obviously there
are lots of things to catch up with :)

At a quick glance at Youssef's first reply, I'm sure that's exactly
the same as I thought about, the EVDF. The intention behind is w/o
eligibility the task_timeline can be organized by deadline rather
than vruntime, hence task selection can be done in O(1) while the
min_vruntime can be updated through augmented rbtree.

Anyway, I will learn from your discussion with Youssef first, thanks
for providing the info!

Best,
	Abel