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Wed, 29 Jul 2020 02:49:45 -0700 (PDT) Date: Wed, 29 Jul 2020 12:49:43 +0300 From: Vladimir Oltean To: Kurt Kanzenbach Subject: Re: [RFC PATCH] arm64: defconfig: Disable fine-grained task level IRQ time accounting Message-ID: <20200729094943.lsmhsqlnl7rlnl6f@skbuf> References: <20200729033934.22349-1-alison.wang@nxp.com> <877dumbtoi.fsf@kurt> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <877dumbtoi.fsf@kurt> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200729_054950_706751_2EEF534E X-CRM114-Status: GOOD ( 18.89 ) 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 Wed, Jul 29, 2020 at 10:40:29AM +0200, Kurt Kanzenbach wrote: > Hi Alison, > > On Wed Jul 29 2020, Alison Wang wrote: > > In the current arm64 defconfig, CONFIG_IRQ_TIME_ACCOUNTING is enabled as > > default. According to my tests on NXP's LayerScape and i.MX platforms, > > the system hangs when running the command "stress-ng --hrtimers 1" with > > CONFIG_IRQ_TIME_ACCOUNTING enabled. Disabling this option, the issue > > disappears. CONFIG_IRQ_TIME_ACCOUNTING causes serious performance impact > > when running hrtimer stress test at the same time. > > I think instead of disabling the option for all arm64 devices, it might > be better to analyze the root-cause why the hrtimer test hangs when this > option is enabled. > > +Cc hrtimer maintainers: Thomas and Anna-Maria > > Thanks, > Kurt 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. Thanks, -Vladimir _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel