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