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bh=kA4MurLmU5SxwWcecswp4Ycsr4tLHf95RZmBe+KV4Os=; b=LIiPydyIabQcexxpMGlHDwk+xDOwD49YeVE2z3EFDkv4NOkGQWKrRMz/w0qwCEIgoia2TC Sj9iBqTx3uyhhHcZ81eGCrVLWNAX1fyEcOPvglWi30UXBO7kNnE3O5UmGQOpY9CCIZz4SL FrY4p9p08wpyliiYpKWf5vjQvjBglWco7ewffQ/HYuwMf/Z+jXBELPB7oRMarMSld5OVjM U0XQFWNmM4yXgKIPQab2vssaNZy1pxxnWWcYzwC8THlNIYQ62vPtwa1C7VWYdj0CfALXPk rogzb/UV4U7ehUWtgJi9Cmv0CcLnrH8mIRUuOGiENY1ybpmlhVnRYJ2nexXX1Q== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1716980130; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=kA4MurLmU5SxwWcecswp4Ycsr4tLHf95RZmBe+KV4Os=; b=kWMmKXMouZlb+L2nNi1Gctnzl7Fmj8Wnd+alYWGuPzfsL8UgoSIOWdwof0ZhHtnnsOJBZ6 138VYhyCmiD3z4AQ== From: Sebastian Andrzej Siewior To: Qais Yousef Cc: Ingo Molnar , Peter Zijlstra , Juri Lelli , Steven Rostedt , Vincent Guittot , Daniel Bristot de Oliveira , Thomas Gleixner , Alexander Viro , Christian Brauner , Andrew Morton , Jens Axboe , linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, linux-mm@kvack.org, Phil Auld Subject: Re: [PATCH v2] sched/rt: Clean up usage of rt_task() Message-ID: <20240529105528.9QBTCqCr@linutronix.de> References: <20240515220536.823145-1-qyousef@layalina.io> <20240521110035.KRIwllGe@linutronix.de> <20240527172650.kieptfl3zhyljkzx@airbuntu> <20240529082912.gPDpgVy3@linutronix.de> <20240529103409.3iiemroaavv5lh2p@airbuntu> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20240529103409.3iiemroaavv5lh2p@airbuntu> X-Rspam-User: X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: 6CC0D1C0025 X-Stat-Signature: uthsfrtndegsw48j1gf4mkfw7os14h4f X-HE-Tag: 1716980133-142118 X-HE-Meta: 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 4nDYPI3X n6CTI1qLgmgsDKl52d7ctYgA8my4uq45j7GnAJahRRZoez1yFP5YyT2u1dFOTwB+D1e/Zd2Zi4VaRtrfxmbZp/OBBR+3jLdLwwVAbRj9xVxGvbAR+0Tys+i4LEj+tIaRbs3WnWlMwgHIzSDicF1PF4rKodw== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 2024-05-29 11:34:09 [+0100], Qais Yousef wrote: > > behaviour. But then it is insistent which matters only in the RT case. > > Puh. Any sched folks regarding policy? > > I am not sure I understood you here. Could you rephrase please? Right now a SCHED_OTHER task boosted to a realtime priority gets slack=0. In the !RT scenario everything is fine. For RT the slack=0 also happens but the init of the timer looks at the policy instead at the possible boosted priority and uses a different clock attribute. This can lead to a delayed wake up (so avoiding the slack does not solve the problem). This is not consistent because IMHO the clock setup & slack should be handled equally. So I am asking the sched folks for a policy and I am leaning towards looking at task-policy in this case instead of prio because you shouldn't do anything that can delay. Sebastian