From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=90.155.92.199 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1794413960; b=SX034NmBxjemyAesHRk6gs/WBix6iOqpErqBixxNmmSPXs0SPvSxAvgMK87IH/sQNblE L0AAiRB5iTy1ltBpecSO+WxPrFWCwcwNbIEyzF78rS1oItya4kqUJXWYNqt8KnFGI0/Ig VuSnYAuVidh/mNT8ltefo4/RKaAmiLExHIQ93bcKLtI22Akl6Zj231KRaXlJE62lI3a+i et1IB/D/o9v8bx+DIhD+BgJDjUX7MFbyRKs0JRMpHjcNdW5tIqYYHehzyzXO+vxBWqf4R Uxe2OHSNWB60sOxniWvk9ISfxooj0TIDiHy0Eo11tl4DWCigMN3YZm14Vg19O6cf6oA== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794413960; h=DMARC-Filter:DKIM-Signature:Received:Received:Date:From:To:Cc: Subject:Message-ID:References:MIME-Version:Content-Type: Content-Disposition:In-Reply-To; bh=3Tr7kJyMgrxILW6bmy4HJBMvh/+CUoCrlh1UXHmeUfg=; b=2q01niUkEDmujMK0DQJJsThu9t7ddswwi6UENQsX77CIazon2j9+ppR4qJhIqqS0suab nA9rBVRhUjqsT4GJecPl5eJ+WRzWY54JX5UGYdKASEE9IAZ2bUWgXQmi2O84EfY3QF4Q4 O9rqISjv1Dy38LCQUspsQ6FRAxppKvnt82s6In1Mw8udq8iT6Gf66KAv99uw/YtrqT8fW 9mlYSDUjTkxCmnyKFid8rWw7mfrzLmWfQY5UAWAHi4JNoMvIXsPIjCoim64Pnajhz5DBK IQEzcZ/jb6rSD1HvwQkNkA8mjdPRetayijPrTHtGvLMzPjddwO0mUoHaHIsiBjhlrqA== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass header.from=infradead.org; spf=pass smtp.mailfrom=infradead.org; dkim=pass header.d=infradead.org header.i=@infradead.org header.a=rsa-sha256 header.s=desiato.20200630 header.b=JCvYPm5I; arc=none smtp.remote-ip=90.155.92.199 Received: from desiato.infradead.org (desiato.infradead.org [90.155.92.199]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 40175606A32D; Wed, 11 Nov 2026 16:19:20 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.2 smtp.subspace.kernel.org 40175606A32D Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=infradead.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=infradead.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.a=rsa-sha256 header.s=desiato.20200630 header.b=JCvYPm5I DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=desiato.20200630; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=3Tr7kJyMgrxILW6bmy4HJBMvh/+CUoCrlh1UXHmeUfg=; b=JCvYPm5Is+991YuywRlzjEMNp1 S7xApyjWkrIWpO1oeaL8ktGurfYFlNjlkCO5QDII88oChRyKxzldRJdHvNh12Qc9AqcRnnTbfHGgi m24D8VAzk2xKVIS6fw5o+v0JyHDFmq1xcpGCCBrxJb/8xYuWZMHFFVQYsq7++pn3jgfUQgXXxRzch 9z4ADnYmpKTG72LwmxGF3ubyCFpL4b2Bw6SoxxtCFFZqjGjzvQLkdiEurQL6UszAOmvSbqcHjpFEp ZQ6NLGlEPWFuQUKKypZ/upo4qvHU052VKpB4y13ADLWF5cwZm2yeau3pKtixdT09vC++p/dFkG29U Ia7lrXtA==; Received: from 77-249-17-252.cable.dynamic.v4.ziggo.nl ([77.249.17.252] helo=noisy.programming.kicks-ass.net) by desiato.infradead.org with esmtpsa (Exim 4.100.1 #2 (Red Hat Linux)) id 1xRB2X-00000009KMT-3SmB; Wed, 11 Nov 2026 16:19:14 +0000 Received: by noisy.programming.kicks-ass.net (Postfix, from userid 1000) id 3D91130031E; Wed, 11 Nov 2026 17:19:12 +0100 (CET) Date: Wed, 11 Nov 2026 17:19:12 +0100 From: Peter Zijlstra To: Mathieu Desnoyers Cc: Juri Lelli , mingo@redhat.com, vincent.guittot@linaro.org, linux-kernel@vger.kernel.org, tglx@kernel.org, will@kernel.org, boqun@kernel.org, dietmar.eggemann@arm.com, rostedt@goodmis.org, bsegall@google.com, mgorman@suse.de, vschneid@redhat.com, kprateek.nayak@amd.com, luca.abeni@santannapisa.it, mathieu.poirier@linaro.org, longman@redhat.com, ridong.chen@linux.dev, tj@kernel.org, hannes@cmpxchg.org, mkoutny@suse.com, shuah@kernel.org, bigeasy@linutronix.de, clrkwllms@kernel.org, parri.andrea@gmail.com, m.szyprowski@samsung.com, kayracizmeci@gmail.com, weihengqiuu@gmail.com, cgroups@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-rt-devel@lists.linux.dev, stable@vger.kernel.org Subject: Re: [PATCH v5 13/29] sched/deadline: Keep departing bandwidth across a root domain rebuild Message-ID: <20261111161912.GP1779021@noisy.programming.kicks-ass.net> References: <20261108185406.1549770-1-mathieu.desnoyers@efficios.com> <20261108185406.1549770-14-mathieu.desnoyers@efficios.com> X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On Wed, Nov 11, 2026 at 10:35:17AM -0500, Mathieu Desnoyers wrote: > Measured in a 64-vCPU guest with sleeping deadline tasks: > > tasks today: rebuild, longest irqs-off single list, all irqs-off > 1000 0.75ms, under 0.1ms 0.12ms (0.19ms worst) > 10000 7.4ms, under 0.1ms (0.3ms once) 0.9ms (1.2ms worst) > > The rebuild itself is 8 times shorter. That comes from updating the > extra_bw of the CPUs once per root domain, not once per task. But the > longest section with interrupts disabled grows with the number of > deadline tasks. I do not think that is a step forward for a real-time > class. This is domain rebuild? Do we really care about performance there?