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;
MIME-Version: 1.0
References: <20190911140204.GA52872@aaronlu> <7b001860-05b4-4308-df0e-8b60037b8000@linux.intel.com>
 <CANaguZCH-jjHrWwycU3vz6RfNkW9xN+DoRkHnL3n8-DneNV3FQ@mail.gmail.com>
 <20190912123532.GB16200@aaronlu> <CANaguZBTiLQiRQU9MJR2Qys8S2S=-PTe66_ZPi5DVzpPbJ93zw@mail.gmail.com>
 <CANaguZDOb+rVcDPMS+SR1DKc73fnctkBK0EbfBrf90dztr8t=Q@mail.gmail.com>
 <20191010135436.GA67897@aaronlu> <CANaguZDCtmXpm_rpTkjsfPPBscHCwz4u1OHwUt3XztzgLJa_jA@mail.gmail.com>
 <20191011073338.GA125778@aaronlu> <CANaguZCkKQTmgye+9nQhzQqYBrsnCmcjA46TPmLwN60vvMQ_7w@mail.gmail.com>
 <20191011114851.GA8750@aaronlu>
In-Reply-To: <20191011114851.GA8750@aaronlu>
From:   Vineeth Remanan Pillai <vpillai@digitalocean.com>
Date:   Fri, 11 Oct 2019 08:10:30 -0400
Message-ID: <CANaguZBgv5N2Spv-Ldio5Umn6qU7dC0Px66sL9s11W7SK3f4Hg@mail.gmail.com>
Subject: Re: [RFC PATCH v3 00/16] Core scheduling v3
To:     Aaron Lu <aaron.lu@linux.alibaba.com>
Cc:     Tim Chen <tim.c.chen@linux.intel.com>,
        Julien Desfossez <jdesfossez@digitalocean.com>,
        Dario Faggioli <dfaggioli@suse.com>,
        "Li, Aubrey" <aubrey.li@linux.intel.com>,
        Aubrey Li <aubrey.intel@gmail.com>,
        Nishanth Aravamudan <naravamudan@digitalocean.com>,
        Peter Zijlstra <peterz@infradead.org>,
        Ingo Molnar <mingo@kernel.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Paul Turner <pjt@google.com>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Linux List Kernel Mailing <linux-kernel@vger.kernel.org>,
        =?UTF-8?B?RnLDqWTDqXJpYyBXZWlzYmVja2Vy?= <fweisbec@gmail.com>,
        Kees Cook <keescook@chromium.org>,
        Greg Kerr <kerrnel@google.com>, Phil Auld <pauld@redhat.com>,
        Valentin Schneider <valentin.schneider@arm.com>,
        Mel Gorman <mgorman@techsingularity.net>,
        Pawan Gupta <pawan.kumar.gupta@linux.intel.com>,
        Paolo Bonzini <pbonzini@redhat.com>
Content-Type: text/plain; charset="UTF-8"
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

> Thanks for the clarification.
>
> Yes, this is the initialization issue I mentioned before when core
> scheduling is initially enabled. rq1's vruntime is bumped the first time
> update_core_cfs_rq_min_vruntime() is called and if there are already
> some tasks queued, new tasks queued on rq1 will be starved to some extent.
>
> Agree that this needs fix. But we shouldn't need do this afterwards.
>
> So do I understand correctly that patch1 is meant to solve the
> initialization issue?

I think we need this update logic even after initialization. I mean, core
runqueue's min_vruntime can get updated every time when the core
runqueue's min_vruntime changes with respect to the sibling's min_vruntime.
So, whenever this update happens, we would need to propagate the changes
down the tree right? Please let me know if I am visualizing it wrong.

Thanks,
Vineeth