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From: Joel Fernandes <joelagnelf@nvidia.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: linux-kernel@vger.kernel.org, Andrea Righi <arighi@nvidia.com>,
	Tejun Heo <tj@kernel.org>, Ingo Molnar <mingo@redhat.com>,
	Juri Lelli <juri.lelli@redhat.com>,
	Vincent Guittot <vincent.guittot@linaro.org>,
	Dietmar Eggemann <dietmar.eggemann@arm.com>,
	Steven Rostedt <rostedt@goodmis.org>,
	Ben Segall <bsegall@google.com>, Mel Gorman <mgorman@suse.de>,
	Valentin Schneider <vschneid@redhat.com>,
	David Vernet <void@manifault.com>,
	Changwoo Min <changwoo@igalia.com>,
	Luigi De Matteis <ldematteis123@gmail.com>,
	paulmck@kernel.org, boqun.feng@gmail.com
Subject: Re: [PATCH RFC 3/8] sched/ext: Add a DL server for sched_ext tasks
Date: Sat, 15 Mar 2025 19:15:27 -0400	[thread overview]
Message-ID: <3b244939-6d55-4d86-8b77-a9a7629f8239@nvidia.com> (raw)
In-Reply-To: <20250315072225.GG36322@noisy.programming.kicks-ass.net>



On 3/15/2025 3:22 AM, Peter Zijlstra wrote:
> On Fri, Mar 14, 2025 at 10:21:50PM -0400, Joel Fernandes wrote:
>> sched_ext currently suffers starvation due to RT. The same workload when
>> converted to EXT can get zero runtime if RT is 100% running, causing EXT
>> processes to stall. Fix it by adding a DL server for EXT.
> 
> This needs a lot more words on why you need a second server. Because I
> don't think you do.

Sure, I will add more words to the change log to explain rationale. When you say
"I don't think you do", do you mean that both FAIR and EXT could be served by
the same server? If so, that will not handle the case where the system has both
FAIR and EXT tasks in the mix (EXT has a partial mode where certain tasks can be
made EXT with certain others left as FAIR) and FAIR runs 100% and starves EXT.
We still need bandwidth allocated to EXT in such a situation. So we do need an
EXT server. Or did you mean something else?

thanks,

 - Joel


  reply	other threads:[~2025-03-15 23:15 UTC|newest]

Thread overview: 23+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-03-15  2:21 [PATCH RFC 0/8] Add a deadline " Joel Fernandes
2025-03-15  2:21 ` [PATCH RFC 1/8] sched: Add support to pick functions to take rf Joel Fernandes
2025-03-15  2:21 ` [PATCH RFC 2/8] sched: Add a server arg to dl_server_update_idle_time() Joel Fernandes
2025-03-15  2:21 ` [PATCH RFC 3/8] sched/ext: Add a DL server for sched_ext tasks Joel Fernandes
2025-03-15  7:22   ` Peter Zijlstra
2025-03-15 23:15     ` Joel Fernandes [this message]
2025-03-17 10:31       ` Peter Zijlstra
2025-03-17 16:57         ` Tejun Heo
2025-03-17 17:06           ` Peter Zijlstra
2025-03-17 21:48             ` Joel Fernandes
2025-03-17 22:16               ` Tejun Heo
2025-03-17 22:39                 ` Joel Fernandes
2025-03-17 22:48                   ` Tejun Heo
2025-03-18 10:07                     ` Joel Fernandes
2025-03-17 21:53         ` Joel Fernandes
2025-03-15 17:56   ` Andrea Righi
2025-03-15 23:17     ` Joel Fernandes
2025-03-15  2:21 ` [PATCH RFC 4/8] sched/debug: Fix updating of ppos on server write ops Joel Fernandes
2025-03-15  2:21 ` [PATCH RFC 5/8] sched/debug: Stop and start server based on if it was active Joel Fernandes
2025-03-15  2:21 ` [PATCH RFC 6/8] sched/debug: Add support to change sched_ext server params Joel Fernandes
2025-03-15  2:21 ` [PATCH RFC 7/8] sched/deadline: Clear defer params Joel Fernandes
2025-03-15  2:21 ` [PATCH RFC 8/8] selftests/sched_ext: Add test for sched_ext dl_server Joel Fernandes
2025-03-15 23:22   ` Joel Fernandes

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