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=1793898726; b=FD0lyU06XLtIwQgx/DNTIAQpKH3DUxF+FsMR4ceRwl6OyUeqSwnH6ceTiWnE/GWIH1gw aO1EJJLcF2IRpV3Ez0vLfBUEO/DjFiauxyuVeh7ovLecJW7dUPJCjUmBpY20wmYPQEhUI ENR+F5MEHtgC1vtNoH0FhpSGCXQ2pICA8fUl2gsupbm9UkqzLfqLCDygt+DRg8H2vv4A1 62jdOZTSUdBcqoYHfwignRMA5LCUvKgOHPJefavwgXsi3b13ITIdHC8uQD8KySA4gIB3j mUC6OCuU8ZZtxuL5jy25jelnwL1oKvSwr4qhk2GN/vcI/f5UXXQ5mqosXn7cQeEmN2w== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793898726; h=DMARC-Filter:DKIM-Signature:Received:Received:Message-ID:User-Agent: Date:From:To:Cc:Subject; bh=otYT/SsWPwsr7S7pEQzyQCYmb6TgtQ9g4U14CcO6S0w=; b=XgJfm4dtKrRAgdbKcKepsFE6m1IC7eAm41jOLQ/DuU7ci8/yPcPd4okYIgHMXHYg7yRW Jt1OQZC5UTl+7W5vK9pfYtyWecEZRA8S5KaSvadmLDLB3eN4ubD/ficFd0i9POP7Zh6rF IFd3T/pUjF/vxRW4LqprPWuUI/HDw2t7Px3SXTbXtWafZiho+eg1oAJEhrGB4n4uu0s/H /cC0oFcR7MRTGVtFPWyog5egvz1qcFgITSxuggs86Gcjd2pYzG4FRU13TEmd2jKkeyiHU 0OrPniNX8S+vJXLaygON1cNG3EHjw7db2fZO3TqrhkyVfE6cjhqtfd7VBdu4TNMcgCA== 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=SqAsGNPe; 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 E0F03606A328 for ; Thu, 5 Nov 2026 17:12:04 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.2 smtp.subspace.kernel.org E0F03606A328 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, unprotected) header.d=infradead.org header.i=@infradead.org header.a=rsa-sha256 header.s=desiato.20200630 header.b=SqAsGNPe DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=desiato.20200630; h=Subject:Cc:To:From:Date:Message-ID: Sender:Reply-To:MIME-Version:Content-Type:Content-Transfer-Encoding: Content-ID:Content-Description:In-Reply-To:References; bh=otYT/SsWPwsr7S7pEQzyQCYmb6TgtQ9g4U14CcO6S0w=; b=SqAsGNPeIv10uQhciTLK5uHvBZ xyHaC1aP35fDS0zvhkGcIZ+Q16pRPGnLlRLfAahNjH3qo3ZVhzwu/GpHtF/+9RfJY0TS+qc8YEx86 9EVQraFG/ZkH9C6Ra2xbmFzL+8gfZSwTy0ursSuKvqOjb0sovtrMjygJ/loLscDO5c0Nmd613ECmM L1V/BzVEflXq7JJoJ7++EKe3suOwoOTaI6EQWq+TffSqmg3Z/pzv298gVbPtafnEgxEkGKQASELW3 L6T/FHXaTHKRl3nKWIlnCUPjRfduvlJtnQrDAwzuLQwCzLC2W79C0lXm8P7pNpwHQlw/R1ScsQlum j0kvJbVA==; 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 1xP10H-00000003JiY-2YoA; Thu, 05 Nov 2026 17:11:57 +0000 Received: by noisy.programming.kicks-ass.net (Postfix, from userid 0) id 665A3300399; Thu, 05 Nov 2026 18:11:56 +0100 (CET) Message-ID: <20261105165525.011876858@infradead.org> User-Agent: quilt/0.68 Date: Thu, 05 Nov 2026 17:55:25 +0100 From: Peter Zijlstra To: mingo@kernel.org Cc: linux-kernel@vger.kernel.org, peterz@infradead.org, juri.lelli@redhat.com, vincent.guittot@linaro.org, dietmar.eggemann@arm.com, rostedt@goodmis.org, bsegall@google.com, mgorman@suse.de, vschneid@redhat.com, kprateek.nayak@amd.com, joshdon@google.com, tj@kernel.org, jakub@okonski.org Subject: [PATCH 0/3] sched/fair: Fix cgroup::idle preemption X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list Hi! so I finally got around to looking at this again with a fresh mind and an LLM generated testcase. It appears to actually work now. I'm still not convinced on the whole find_matching_se() thing; at the end of the day we mark a subtree 'idle', which is akin to saying 'dont care', so then actually caring about how it ends up preempting on a different level is weird to me. As such, I have Vincent's patch last; modified to use the new idle state as optimization.