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a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1596706866; 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=7h1NwChE7k/KZnYmQuWPK12OfyVN6+DmIy8syMh+/Ks=; b=4eBnpOGf08nGpnL+jnNqH5dmgNbgf5eT0rVBjjVBHEiNG3JQgMsYvX+22Ccpdz12hJBVUZ WJupblTyigLCvCCw== To: peterz@infradead.org, Valentin Schneider Subject: Re: [RFC PATCH] arm64: defconfig: Disable fine-grained task level IRQ time accounting In-Reply-To: <20200805153120.GU2674@hirez.programming.kicks-ass.net> References: <87mu3ho48v.fsf@kurt> <20200730082228.r24zgdeiofvwxijm@skbuf> <873654m9zi.fsf@kurt> <87lfiwm2bj.fsf@nanos.tec.linutronix.de> <20200803114112.mrcuupz4ir5uqlp6@skbuf> <87d047n4oh.fsf@nanos.tec.linutronix.de> <875z9zmt4i.fsf@nanos.tec.linutronix.de> <20200805134002.GQ2674@hirez.programming.kicks-ass.net> <20200805153120.GU2674@hirez.programming.kicks-ass.net> Date: Thu, 06 Aug 2020 11:41:06 +0200 Message-ID: <874kpgi025.fsf@nanos.tec.linutronix.de> MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200806_054108_790204_842D038A X-CRM114-Status: GOOD ( 11.44 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: mw@semihalf.com, paulmck@kernel.org, Anna-Maria Gleixner , catalin.marinas@arm.com, Alison Wang , linux-kernel@vger.kernel.org, leoyang.li@nxp.com, vladimir.oltean@nxp.com, Kurt Kanzenbach , Vladimir Oltean , will@kernel.org, linux-arm-kernel@lists.infradead.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org peterz@infradead.org writes: > On Wed, Aug 05, 2020 at 02:56:49PM +0100, Valentin Schneider wrote: > >> I've been tempted to say the test case is a bit bogus, but am not familiar >> enough with the RT throttling details to stand that ground. That said, from >> both looking at the execution and the stress-ng source code, it seems to >> unconditionally spawn 32 FIFO-50 tasks (there's even an option to make >> these FIFO-99!!!), which is quite a crowd on monoCPU systems. > > Oh, so it's a case of: we do stupid without tuning and the system falls > over. I can live with that. It's not a question of whether you can live with that behaviour for a particular silly test case. The same happens with a single RT runaway task with enough interrupt load on a UP machine. Just validated that. And that has nothing to do with a silly test case. Sporadic runaways due to a bug in a once per week code path simply can happen and having the safety net working depending on a config option selected or not is just wrong. Thanks, tglx _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel