linux-kernel - Re: [PATCH v5 08/14] sched/ext: Add a DL server for sched

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <fe794099-50d4-49f2-ad75-b586157793ac@nvidia.com>
Date: Tue, 1 Jul 2025 09:23:00 -0400
From: Joel Fernandes <joelagnelf@...dia.com>
To: Tejun Heo <tj@...nel.org>
Cc: linux-kernel@...r.kernel.org, Ingo Molnar <mingo@...hat.com>,
 Peter Zijlstra <peterz@...radead.org>, Juri Lelli <juri.lelli@...hat.com>,
 Vincent Guittot <vincent.guittot@...aro.org>,
 Dietmar Eggemann <dietmar.eggemann@....com>,
 Steven Rostedt <rostedt@...dmis.org>, Ben Segall <bsegall@...gle.com>,
 Mel Gorman <mgorman@...e.de>, Valentin Schneider <vschneid@...hat.com>,
 David Vernet <void@...ifault.com>, Andrea Righi <arighi@...dia.com>,
 Changwoo Min <changwoo@...lia.com>,
 Luigi De Matteis <ldematteis123@...il.com>, sched-ext@...ts.linux.dev
Subject: Re: [PATCH v5 08/14] sched/ext: Add a DL server for sched_ext tasks

Hi Tejun,

On 6/30/2025 11:38 AM, Tejun Heo wrote:
>> This changes the signature of the pick_task_dl function, which in turn
>> changes the signature of class->pick_task.
>>
>> How about I pass NULL to pick_task_scx() from ext_server_pick_task(), and
>> also annotate all functions where rf is unused, by naming the argument as
>> rf_unused (except for DL), would that make it more clear that the rq lock
>> should not be arbitrarily dropped just because rf was passed? And perhaps
>> sprinkling some more code comments.
>
> I think what bothers me is that this erases the distinction between
> ->balance() and ->pick_task(). However, I'm not sure the distinction means
> anything anymore especially given the removal of !CONFIG_SMP paths. Looking
> at the balance callsites, I think we can just fold each ->balance() into the
> head of the corresponding ->pick_task(). Peter, what do you think?

I think one added complexity with that would be, the ->balance() would be have
to be embedded into the other sister ->pick_next_task() as well?

And core scheduling paths add complexity there, I'd vouch for keeping it
separate but curious what Peter has to say as well.

thanks,

 - Joel