From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 7D43F2F8E81; Thu, 14 May 2026 04:48:32 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778734112; cv=none; b=XzYqrV3UgfYwGEn8Bf1fhdtu8M2eqgJ46kJNowHa1HUq0xP9iD8yvW/lh59WeaWVHGLCz/hHgh10SdHAyIcSWHX0rpMkspEpVt4QDgVipfeUv1coAd01F0Kqb7gvpRgwxm/37gbw5Grd80U+xlMNvWxt7mCWHWrXzJCxO/sjCrg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778734112; c=relaxed/simple; bh=77OhJcmWcVYCdR6+BjbtMuX6789Ua3m10DtUXbH1vP4=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=CeuEalMziOJNdPkk7tfWfyuG45ntgDj+25jgJict24OkBfW1sbzoWmmTwt3Yz8MFl0NUALqro4JjclDuHGqvu/U1UtXL30rf/gT930FLtx6byPBVJonUnllduZ5ipZ51ehR4ZtlbD4KhPfrV8jtjXoNBumGBiG8J4k+o44xVajg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=HClYxTwL; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="HClYxTwL" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 38E27C2BCB7; Thu, 14 May 2026 04:48:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1778734112; bh=77OhJcmWcVYCdR6+BjbtMuX6789Ua3m10DtUXbH1vP4=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=HClYxTwLySkTuDtqtV+KD94LQ60TGm6hgyRCr27ExCYxxee1FXMZRqg21twvrl52Y mtRiGLtj+DbIqAiuLyr1dozSFu6XsjH0EAVHjuYAUhK/+n3USr0j2pSjwS8zAyRU1c ejzO7lKqd2CmTW7B11p1XmyXRNmasHEA3XpmL+q2CA7x+OVg9f06V0egLVZwMUKbeX F19fu4+AQOMOhG/1Ljk25mIRGqxZR6QbUKjilsiPqfYSEym2DsjMp/vVP9atZ1EhEg zUVsPolexA1k7FVtP6AR+zt3sGbwazFKJD2o3TG0/nd1Ppw2BOPomMQKfbUhzVUItZ 7GJF9t0bgQ/Sg== Date: Wed, 13 May 2026 18:48:31 -1000 From: Tejun Heo To: Steven Rostedt Cc: Peter Zijlstra , Ingo Molnar , Juri Lelli , Vincent Guittot , Dietmar Eggemann , Ben Segall , Mel Gorman , Valentin Schneider , K Prateek Nayak , Kyle McMartin , linux-kernel@vger.kernel.org, stable@vger.kernel.org, Linux RT Development , Clark Williams , Sebastian Andrzej Siewior , John Kacur Subject: Re: [PATCH sched/core] sched/rt: Fix RT_PUSH_IPI soft lockup loop Message-ID: References: <20260507141437.GJ3102624@noisy.programming.kicks-ass.net> <20260512113754.448c1f5b@gandalf.local.home> <056f95bc5805f7e161458984fff4b3cb@kernel.org> <20260512172847.5024e5e8@gandalf.local.home> <20260513193914.1593369-1-tj@kernel.org> <20260513202432.18dd7b9f@gandalf.local.home> <20260513213108.2870a1e7@fedora> <20260513220136.5a11c740@fedora> Precedence: bulk X-Mailing-List: linux-rt-devel@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260513220136.5a11c740@fedora> Hello, On Wed, May 13, 2026 at 10:01:36PM -0400, Steven Rostedt wrote: > I could try, but there are still some things that I don't understand. > One is that to send more IPIs due to the RT pull request, there needs > to be RT tasks constantly sleeping. Is that happening in this use case? > Are the softirqs waking up RT tasks that run for a short time and go > back to sleep, causing the pull IPI to trigger again? Ah, yes, that makes sense. That's why the repro is using FIFO threads too. In prod, there's mpi3mr threaded irq handlers that are FIFO. These are storage machines so they're also constantly active. Thanks. -- tejun