Re: [PATCH v5 7/7] sched/fair: Fair server interface

From: Daniel Bristot de Oliveira <bristot@kernel.org>
To: Ingo Molnar <mingo@redhat.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Juri Lelli <juri.lelli@redhat.com>,
	Vincent Guittot <vincent.guittot@linaro.org>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>,
	Steven Rostedt <rostedt@goodmis.org>,
	Ben Segall <bsegall@google.com>, Mel Gorman <mgorman@suse.de>,
	Daniel Bristot de Oliveira <bristot@redhat.com>,
	Valentin Schneider <vschneid@redhat.com>,
	linux-kernel@vger.kernel.org,
	Luca Abeni <luca.abeni@santannapisa.it>,
	Tommaso Cucinotta <tommaso.cucinotta@santannapisa.it>,
	Thomas Gleixner <tglx@linutronix.de>,
	Vineeth Pillai <vineeth@bitbyteword.org>,
	Shuah Khan <skhan@linuxfoundation.org>,
	Phil Auld <pauld@redhat.com>,
	Suleiman Souhlal <suleiman@google.com>,
	youssefesmat@google.com, Joel Fernandes <joel@joelfernandes.org>
Subject: Re: [PATCH v5 7/7] sched/fair: Fair server interface
Date: Thu, 4 Apr 2024 19:43:57 +0200	[thread overview]
Message-ID: <578bf1c5-4102-4048-b5f3-6961963a119f@kernel.org> (raw)
In-Reply-To: <b3e053bf-c9f5-492d-baff-8f251fb00279@joelfernandes.org>

On 2/15/24 18:41, Joel Fernandes wrote:
>> Thanks for taking a look. My colleague Suleiman hit the issue too. He's able to
>> not set 45ms/50ms for instance.
> I isolated the problem. It is not an interface problem.
> 
> Long story short, the servers are initialized at the defrootdomain, but
> the dl_bw info is not being carried over to the new domain because the
> servers are not a task.

Fixed on v6. When an rq is attached to a new rd, at rq_attach_root(), the bw of
from fair server is being added to the new rd.

Without this, the RD has no bandwidth registered (no-dl task) and so the
admission control becomes broken.

-- Daniel