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Thu, 30 Jul 2020 01:22:30 -0700 (PDT) Date: Thu, 30 Jul 2020 11:22:28 +0300 From: Vladimir Oltean To: Kurt Kanzenbach Subject: Re: [RFC PATCH] arm64: defconfig: Disable fine-grained task level IRQ time accounting Message-ID: <20200730082228.r24zgdeiofvwxijm@skbuf> References: <20200729033934.22349-1-alison.wang@nxp.com> <877dumbtoi.fsf@kurt> <20200729094943.lsmhsqlnl7rlnl6f@skbuf> <87mu3ho48v.fsf@kurt> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <87mu3ho48v.fsf@kurt> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200730_042233_099630_3DB9C851 X-CRM114-Status: GOOD ( 21.47 ) 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: 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, Thomas Gleixner , mw@semihalf.com, 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 On Thu, Jul 30, 2020 at 09:23:44AM +0200, Kurt Kanzenbach wrote: > Hi Vladimir, > > On Wed Jul 29 2020, Vladimir Oltean wrote: > > For more context, here is my original report of the issue: > > https://lkml.org/lkml/2020/6/4/1062 > > > > Just like you, I could not reproduce the RCU stalls and system hang on a > > 5.6-rt kernel, just on mainline and derivatives, using the plain > > defconfig. > > > > The issue is not specific to Layerscape or i.MX8, but rather I was able > > to see the same behavior on Marvell Armada 37xx as well as Qualcomm > > MSM8976. > > > > So, while of course I agree that disabling IRQ time accounting for arm64 > > isn't a real solution, it isn't by far an exaggerated proposal either. > > Nonetheless, the patch is just a RFC and should be treated as such. We > > are at a loss when it comes to debugging this any further and we would > > appreciate some pointers. > > Yeah, sure. I'll try to reproduce this issue first. So it triggers with: > > * arm64 > * mainline, not -rt kernel > * opened serial console > * irq accounting enabled > > Anything else? > > Thanks, > Kurt Thanks for giving a helping hand, Kurt. The defconfig should be enough. In the interest of full disclosure, the only arm64 device on which we didn't reproduce this was the 16-core LX2160A. But we did reproduce on that with maxcpus=1 though. And also on msm8976 with all 8 cores booted. Just mentioning this in case you're testing on a 16-core system, you might want to reduce the number a bit. Thanks, -Vladimir _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel