From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) (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 CF743246BB9 for ; Wed, 29 Oct 2025 18:06:32 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.133.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1761761194; cv=none; b=bNGZONuMud4R3b8p70fcaXNQ55g8L/ekSUa3hBUNvDOkfnup2ZeubyQnh+xOLH/ZtlC6y/up4kU8GM3B2+3Vuxe+P8qdE1YIwTTzdJatF65b1bX5eLp3n9F+foOMiEg7Lb0e3mxBFAKD9yXYWJiDY48KCnnjZR68dIjcXQgMOuQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1761761194; c=relaxed/simple; bh=9b8fa0Z4aKyzjlBhpiWw7f1pqpaADXZXoSC2CTbbwjA=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=FeSz4K3WwXmvwHWxbMO2jFO2d5e5IVe3fj0neCcUII1pXuq3OJbFzjGdP1VZ667NXo5KG6vkgodm9iamiyN15ODoRQJaSiefRGUN9NippEhJ6bbwlWSF0sa5Sz5o3e75nTzOhRiZIAKTFqm+RaaqJo7oPYNJPjd0WWFneEw14C0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=J3ZNnEW/; arc=none smtp.client-ip=170.10.133.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="J3ZNnEW/" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1761761192; 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=5ZfLqAcbRHxrnYziCYWRvgm+ru2d0JIR1i0V2VmmB+Y=; b=J3ZNnEW/MOuFjXjBTC1G1JUFxlMdGjdFl4OR9fUmjAfz8KkTOQqC5z9pIlKP76+XaVS+vL s35Dey56eFUaRtVh0YBvJpOPma6xvkvavkDkS+74f09oXLVkFgz4XaYoKzY43JYh/HjWfx YsFXLJHaLOshzI6BBtTvHAkGA/9DH8E= Received: from mx-prod-mc-08.mail-002.prod.us-west-2.aws.redhat.com (ec2-35-165-154-97.us-west-2.compute.amazonaws.com [35.165.154.97]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-588-WIyi2CbMOkqzfQvzj0zY-Q-1; Wed, 29 Oct 2025 14:06:28 -0400 X-MC-Unique: WIyi2CbMOkqzfQvzj0zY-Q-1 X-Mimecast-MFC-AGG-ID: WIyi2CbMOkqzfQvzj0zY-Q_1761761187 Received: from mx-prod-int-01.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-01.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.4]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-08.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 1E502180737E; Wed, 29 Oct 2025 18:06:27 +0000 (UTC) Received: from tpad.localdomain (unknown [10.96.133.6]) by mx-prod-int-01.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 9E4C330001A2; Wed, 29 Oct 2025 18:06:26 +0000 (UTC) Received: by tpad.localdomain (Postfix, from userid 1000) id AA35940504A61; Wed, 29 Oct 2025 15:01:50 -0300 (-03) Date: Wed, 29 Oct 2025 15:01:50 -0300 From: Marcelo Tosatti To: Frederic Weisbecker Cc: linux-kernel@vger.kernel.org Subject: Re: [PATCH v2] sched/idle: disable tick in idle=poll idle entry Message-ID: References: Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.4 On Wed, Oct 29, 2025 at 03:00:56PM -0300, Marcelo Tosatti wrote: > > Commit a5183862e76fdc25f36b39c2489b816a5c66e2e5 > ("tick/nohz: Conditionally restart tick on idle exit") allows > a nohz_full CPU to enter idle and return from it with the > scheduler tick disabled (since the tick might be undesired noise). > > The idle=poll case still unconditionally restarts the tick when entering > idle. > > To reduce the noise for that case as well, stop the tick when entering > idle, for the idle=poll case. > > Change tick_nohz_full_kick_cpu to set NEED_RESCHED bit, to handle the > case where a new timer is added from an interrupt. This breaks out of > cpu_idle_poll and rearms the timer if necessary. Frederic, As a reminder, this is the original patch and discussion: https://patchew.org/linux/ZIEqlkIASx2F2DRF@tpad/