From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-3.8 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 069BCC433E0 for ; Mon, 3 Aug 2020 10:49:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D8BEE2076C for ; Mon, 3 Aug 2020 10:49:53 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="exPCUDNk"; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="WW2P/omh" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726125AbgHCKtt (ORCPT ); Mon, 3 Aug 2020 06:49:49 -0400 Received: from Galois.linutronix.de ([193.142.43.55]:35218 "EHLO galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725933AbgHCKtj (ORCPT ); Mon, 3 Aug 2020 06:49:39 -0400 From: Thomas Gleixner DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1596451777; 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=KCcHpfOYP09p8zY14r/HtTxM2t9JURMOmwbTy+WTzEQ=; b=exPCUDNkIUSsEk+m93wt286ygaaCqgwqdD6dmnXCCpNcDlS+ANw9TPI9tyr9UedVBK91yK wVaETPEKGYC5SuiO+opVJKVO178taH1yV/dGFfN39zIxD3YgRh+SQcfpoUGQuET13hfuL9 VY5+0MzVXbK17SuypLCIscQQk5nOETJePrsN7SpH255LdJGIceMxTGHnqJtDk2gm+VJSfj R36bdYgczuRW1CHB9G2WXL/hRvLovDRtGtlR0lj8zs6/r7n3svbJEBeGQBrgLPkrNopYWT OfqiQ9u0GZrFZ0ETjfYAHYPjudz5ETLh1r+1fP4Cy4T1KLe2SwNqm/5JGwKmHg== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1596451777; 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=KCcHpfOYP09p8zY14r/HtTxM2t9JURMOmwbTy+WTzEQ=; b=WW2P/omh52HC9kFYVAeeg3h+L56cnLkgbjiWsO8VD72lowVNM28fz0fbaLs9T49RJDULRX eY0JDYKN9PJq8EAA== To: Kurt Kanzenbach , Vladimir Oltean Cc: Alison Wang , catalin.marinas@arm.com, will@kernel.org, paulmck@kernel.org, mw@semihalf.com, leoyang.li@nxp.com, vladimir.oltean@nxp.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Anna-Maria Gleixner , Peter Zijlstra Subject: Re: [RFC PATCH] arm64: defconfig: Disable fine-grained task level IRQ time accounting In-Reply-To: <873654m9zi.fsf@kurt> References: <20200729033934.22349-1-alison.wang@nxp.com> <877dumbtoi.fsf@kurt> <20200729094943.lsmhsqlnl7rlnl6f@skbuf> <87mu3ho48v.fsf@kurt> <20200730082228.r24zgdeiofvwxijm@skbuf> <873654m9zi.fsf@kurt> Date: Mon, 03 Aug 2020 12:49:36 +0200 Message-ID: <87lfiwm2bj.fsf@nanos.tec.linutronix.de> MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Kurt, Kurt Kanzenbach writes: > On Thu Jul 30 2020, Vladimir Oltean wrote: > OK. I've reproduced it on a Marvell Armada SoC with v5.6 mainline. See > splats below. Running with irq time accounting enabled, kills the > machine immediately. However, I'm not getting the possible deadlock > warnings in 8250 as you did. So that might be unrelated. > > Unfortunately I have no idea what to debug here. lets look at the facts we have so far. 1) When irq accounting is disabled, RT throttling kicks in as expected. 2) With irq accounting the RT throttler does not kick in and the RCU stall/lockups happen. Not much, but there is clearly interaction between irq time accounting and scheduler accounting. Can you please reduce /proc/sys/kernel/sched_rt_runtime_us in steps of 50000? At least in theory, reduction should bring the throttling back. Thanks, tglx