linux-kernel - Re: [PATCH resend 2/8] sched: core scheduling tagging infrastructure

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Date:   Fri, 26 Mar 2021 20:19:57 -0700
From:   Josh Don <joshdon@...gle.com>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     "Joel Fernandes (Google)" <joel@...lfernandes.org>,
        Nishanth Aravamudan <naravamudan@...italocean.com>,
        Julien Desfossez <jdesfossez@...italocean.com>,
        Tim Chen <tim.c.chen@...ux.intel.com>,
        Vineeth Pillai <viremana@...ux.microsoft.com>,
        Aaron Lu <aaron.lwe@...il.com>,
        Aubrey Li <aubrey.intel@...il.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        Ingo Molnar <mingo@...nel.org>, torvalds@...ux-foundation.org,
        fweisbec@...il.com, Kees Cook <keescook@...omium.org>,
        Phil Auld <pauld@...hat.com>,
        Valentin Schneider <valentin.schneider@....com>,
        Mel Gorman <mgorman@...hsingularity.net>,
        Pawan Gupta <pawan.kumar.gupta@...ux.intel.com>,
        Paolo Bonzini <pbonzini@...hat.com>, vineeth@...byteword.org,
        Chen Yu <yu.c.chen@...el.com>,
        Christian Brauner <christian.brauner@...ntu.com>,
        Agata Gruza <agata.gruza@...el.com>,
        Antonio Gomez Iglesias <antonio.gomez.iglesias@...el.com>,
        graf@...zon.com, konrad.wilk@...cle.com, dfaggioli@...e.com,
        Steven Rostedt <rostedt@...dmis.org>, benbjiang@...cent.com,
        Alexandre Chartre <alexandre.chartre@...cle.com>,
        James.Bottomley@...senpartnership.com, OWeisse@...ch.edu,
        Dhaval Giani <dhaval.giani@...cle.com>,
        "Hyser,Chris" <chris.hyser@...cle.com>,
        Hao Luo <haoluo@...gle.com>,
        Tom Lendacky <thomas.lendacky@....com>, dhiatt@...italocean.com
Subject: Re: [PATCH resend 2/8] sched: core scheduling tagging infrastructure

Hi Peter,

On Fri, Mar 26, 2021 at 5:10 PM Peter Zijlstra <peterz@...radead.org> wrote:
>
> On Wed, Mar 24, 2021 at 05:40:14PM -0400, Joel Fernandes (Google) wrote:
> > From: Josh Don <joshdon@...gle.com>
> >
> > A single unsigned long is insufficient as a cookie value for core
> > scheduling. We will minimally have cookie values for a per-task and a
> > per-group interface, which must be combined into an overall cookie.
> >
> > This patch adds the infrastructure necessary for setting task and group
> > cookie. Namely, it reworks the core_cookie into a struct, and provides
> > interfaces for setting task and group cookie, as well as other
> > operations (i.e. compare()). Subsequent patches will use these hooks to
> > provide an API for setting these cookies.
> >
>
> *urgh*... so I specifically wanted the task interface first to avoid /
> get-rid of all this madness. And then you keep it :-(

Sorry, I misunderstood the ask here :/ I had separated out the cgroup
interface parts of the patch, leaving (mostly) the parts which
introduced a compound cookie structure. I see now that you just wanted
the plain task interface to start, with no notion of group cookie.

> I've spend the past few hours rewriting patches #2 and #3, and adapting
> #4. The thing was working before I added SHARE_FROM back and introduced
> GET, but now I'm seeing a few FAILs from the selftest.
>
> I'm too tired to make sense of anything much, or even focus my eyes
> consistently, so I'll have to prod at it some more next week, but I've
> pushed out the lot to my queue.git:
>
>   https://git.kernel.org/pub/scm/linux/kernel/git/peterz/queue.git/log/?h=sched/core-sched

Thanks, I'll take a look next week.

> Also, we really need a better name than coretag.c.

Yea, we don't really otherwise use the phrase "tagging". core_sched.c
is probably too confusing given we have sched/core.c.