From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from galois.linutronix.de (Galois.linutronix.de [193.142.43.55]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 31021383A5; Wed, 29 May 2024 10:55:32 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=193.142.43.55 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1716980134; cv=none; b=QD3/n8ugl0SioMPAnfrNFbLbFLI/raL7IrQmJL3pSBPNQl+rTpjIzYmT/wSvNvO5vW1BthMMqCLqByqDKMESKfMXZWnkJ31r/YyHn0kL9R18qLjUQyyQrtAuqwkHavluqn1x8VvKHWcJexAD4AiHUWo+oH3QPYqk9Fh/qhbUdJs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1716980134; c=relaxed/simple; bh=mAikLLuh69xtKMVd3whtMNnLuRnE3TGMOm2WH1S+BsU=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=SpfPFyTc3LxSTFkd/u2rkqocG9k3XqRVYKAySP7HCyEIh8NfwB4C+6E47zs88RVZoBKLnyQ3uvI1LnyQdnZF+xRMwipQCRevx+JLWYWanahYQEsXdHiyfl+WIsFt+fTWofzi6ZTkyS00GM2rHEd23sBw+KuIjjCvGjQC2b34Tdk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de; spf=pass smtp.mailfrom=linutronix.de; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=LIiPydyI; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=kWMmKXMo; arc=none smtp.client-ip=193.142.43.55 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linutronix.de Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="LIiPydyI"; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="kWMmKXMo" Date: Wed, 29 May 2024 12:55:28 +0200 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; 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=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> Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20240529103409.3iiemroaavv5lh2p@airbuntu> 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