Web. But it was not reproduced every time, about 1 time per 5-10 boots. A small debug dump excerpt from the console characterising every stall, copied by hand (in case of any errors and for a detailed trace please consult this image): INFO: rcu_preempt detected stalls on CPUs/tasks: { 0} (detected by 1, t=2102 jiffies, g=50012, c=50011, q=6543) [<8077bd70>] (__schedule) from [<80a7ffa0>] (init_thread_union+0x1fa0. IP27: debugging RCU stalls under newer code. 16 ມ. 000000] Inode-cache hash table entries: 262144 (order: 9, 2097152 bytes) [ 0. >[ 135. Using RCU’s CPU Stall Detector ¶. v4 --> v5: 1. Using the latest versions of kernels and inits I get the following repeating indefinitely: rcu: INFO: rcu_sched self-detected stall on CPU rcu: 0-. 62 Beta BSP. 98 fixes the problem. >> 3. McKenney 0 siblings, 1 reply; 2+ messages in thread From: Zqiang @ 2022-05-18 11:43 UTC (permalink / raw) To: paulmck, frederic; +Cc: rcu, linux-kernel This commit adds a "D" indicator to expedited RCU. Resolve a git am conflict. Resolve a git am conflict. Web. Update comments and document. v5 --> v6: 1. Aligns the output of the last line of RCU stall. v5 --> v6: 1. For a 250 hz kernel a jiffi is 4 milliseconds, and for a 1000 hertz kernel a jiffi is 1 millisecond. Dec 02, 2020 · Soft lockups and RCU sched CPU stalls are detected where many CPUs are looping in a spinlock. v3 --> v4: 1. Like enabling large quantities of tracing. : (20999 ticks this GP) idle=042/1/0x4000000000000002 softirq=8/8 fqs=5248 rcu: (t=21000 jiffies g=-1179 q=18) I tried rolling back just inits to. Fixed a bug in the code. A small debug dump excerpt from the console characterising every stall, copied by hand (in case of any errors and for a detailed trace please consult this image): INFO: rcu_preempt detected stalls on CPUs/tasks: { 0} (detected by 1, t=2102 jiffies, g=50012, c=50011, q=6543) [<8077bd70>] (__schedule) from [<80a7ffa0>] (init_thread_union+0x1fa0. RCU stall warnings and hence system hangs after seeing crashes. 5 and get rcu: notification on the console. ^permalinkrawreply[flat|nested] 5+ messages in thread. rcu: Adjusting geometry for rcu_fanout_leaf=16, . This document. perf_fuzzer, Mark Rutland, Vince Weaver. Using RCU's CPU Stall Detector ¶. The project is very urgent, please give support！. It has NFS/SMB and MDADM installed. 457729] 3-. This will prevent RCU callbacks from ever being invoked, and in a CONFIG_PREEMPT_RCU kernel will further prevent: RCU grace periods from ever completing. > > v5 --> v6: > 1. Aug 01, 2017 · It might well be that the user must disable RCU CPU stall warnings via the rcu_cpu_stall_suppress sysfs entry (or increase their timeout via the rcu_cpu_stall_timeout sysfs entry) before doing something that greatly increases overhead. RCU stalls in dmesg [ 4923. Web. Change "rcu stall" to "RCU stall". : (20999 ticks this GP) idle=042/1/0x4000000000000002 softirq=8/8 fqs=5248 rcu: (t=21000 jiffies g=-1179 q=18) I tried rolling back just inits to. This message indicates that CPU 32 detected that CPUs 2 and 16 were both causing stalls, and that the stall was affecting RCU-sched. Update comments and document. Web. IP27: debugging RCU stalls under newer code. Change "rcu stall" to "RCU stall". Web. Move the start point of statistics from rcu_stall_kick_kthreads() to rcu_implicit_dynticks_qs(), removing the dependency on irq_work. LKML Archive on lore. Ivan Babrou Performance @ Cloudflare. Analyze the vmcore for the root cause of RCU stalls. Change "rcu stall" to "RCU stall". Thanks to Elliott, Robert for the test. Using RCU’s CPU Stall Detector. Web. Web. When a task gets enqueued into a CPU's runqueue, the "stall . 4 george1421 Moderator @Junkhacker Sep 19, 2019, 2:12 PM @Junkhacker @Sebastian-Roth I was able to get the OP going by doing this and that. Finally, this document explains the stall detector's "splat" format. o A CPU looping with interrupts disabled. rcu_assign_pointer () acts like an assignment statement, but does debug checking and enforces ordering on both compiler and CPU as needed. Change "rcu stall" to "RCU stall". Using RCU’s CPU Stall Detector. I am still having trouble reproducing the problem, > > but figured that I should avoid serializing things. Update comments and document. Web. v5 --> v6: 1. perf_fuzzer, Mark Rutland, Vince Weaver. This is quite unlikely, but has occurred at least once in real life. v4 --> v5: 1. v4 --> v5: 1. They have also tried applying: e97a32a5a3bc ("rcu: Do RCU GP kthread self-wakeup from softirq and interrupt") Any suggestions/help are appreciated. This module parameter enables CPU stall detection by default, but may be overridden via boot-time parameter or at runtime via sysfs. A modified kernel module with printk() enabled calls has been loaded for debugging purposes. rcu_cpu_stall_suppress module parameter disables RCU’s CPU stall detector, which detects conditions that unduly delay RCU grace periods. org help / color / mirror / Atom feed * [PATCH] rcu: Add cpu-exp indicator to expedited RCU CPU stall warnings @ 2022-05-18 11:43 Zqiang 2022-05-18 18:14 ` Paul E. h b/kernel/rcu/rcu. The kernel includes an RCU stall detection. When there are more than two continuous RCU stallings, correctly handle the value of the second and subsequent sampling periods. org help / color / mirror / Atom feed * [PATCH] rcu: Add cpu-exp indicator to expedited RCU CPU stall warnings @ 2022-05-18 11:43 Zqiang 2022-05-18 18:14 ` Paul E. Configuration is (excerpt): CONFIG_KASAN_SHADOW_OFFSET=0xdffffc0000000000 CONFIG_HAVE_DEBUG_KMEMLEAK=y CONFIG_DEBUG_KMEMLEAK=y CONFIG_DEBUG_KMEMLEAK_MEM_POOL_SIZE=16000 # CONFIG_DEBUG_KMEMLEAK_TEST is not set. It indicates, "Click to perform a search". Nov 11, 2022 · v1: In some extreme cases, such as the I/O pressure test, the CPU usage may be 100%, causing RCU stall. > + > config RCU_TRACE > bool "Enable tracing for RCU" > depends on DEBUG_KERNEL > diff --git a/kernel/rcu/rcu. 3. root@xilinx-zcu102-2018 _2:~ #. 16 ມ. Resolve a git am conflict. 733084] rcu: blocking rcu_node structures (internal RCU debug): [ 29. Web. Resolve a git am conflict. IP27: debugging RCU stalls under newer code. The RCU callbacks are responsible for performing the necessary RCU work to achieve the end of a grace period. In the vast majority of cases, real-time users face RCU stalls due to the delay of RCU callbacks execution. 000000] Kernel command line: earlycon console=ttyPS0,115200 clk_ignore_unused root=/dev/mmcblk1p2 rw rootwait [ 0. > > v5 --> v6: > 1. Web. From the documentation about RCU stall detector: The following problems can result in RCU CPU stall warnings:. But my observation is that will be less to occur while lower CPU idle (CPU busy). > 3. It is like this 1. Although a RCU Stall can be a side effect of a kernel BUG, this is not the typical case for the real-time kernel users. Nov 11, 2022 · 3. Debugging rcu stalls. Would you please help us in how we can resolve the issue. When CPU idle<10%, RCU stall warnings occurs after >24hour. This time period is normally 20 milliseconds on Android devices. LKML Archive on lore. The RCU callbacks are responsible for performing the necessary RCU work to achieve the end of a grace period. v4 --> v5: 1. Update comments and document. # echo "kernel. Change "rcu stall" to "RCU stall". Add comments and normalize local variable name > > v1 --> v2: > 1. McKenney 0 siblings, 1 reply; 2+ messages in thread From: Zqiang @ 2022-05-18 11:43 UTC (permalink / raw) To: paulmck, frederic; +Cc: rcu, linux-kernel This commit adds a "D" indicator to expedited RCU. Booting with 38400bps, plus enabling CONFIG_RCU_FAST_NO_HZ and CONFIG_RCU_NOCB_CPU. McKenney" <paulmck@kernel. Web. Hi Paul On Sat, 22 Sep 2012, Paul Walmsley wrote: > On Sat, 22 Sep 2012, Paul E. 000000] software IO TLB: mapped [mem 0x7bfff000. Using RCU’s CPU Stall Detector. When there are more than two continuous RCU stallings, correctly handle the value of the second and subsequent sampling periods. h b/kernel/rcu/rcu. 62 Beta BSP. Rear seat removal. In the vast majority of cases, real-time users face RCU stalls due to the delay of RCU callbacks execution. Add Kconfig option CONFIG_RCU_CPU_STALL_DEEP_DEBUG and boot parameter rcupdate. Although a RCU Stall can be a side effect of a kernel BUG, this is not the typical case for the real-time kernel users. Finally, this document explains the stall detector’s “splat” format. from [Joshua Kinard] [Permanent Link] To: Linux/MIPS <linux-mips@linux-mips. Rear seat removal. Anyway, your thread seems to have been held up for 59 seconds (assuming a 250 hertz kernel). org help / color / mirror / Atom feed * [PATCH] rcu: Add cpu-exp indicator to expedited RCU CPU stall warnings @ 2022-05-18 11:43 Zqiang 2022-05-18 18:14 ` Paul E. Web. v4 --> v5: 1. Finally, this document explains the stall detector’s “splat” format. In the vast majority of . 979162] NMI watchdog: BUG: soft lockup - CPU#26 stuck for 23s! [ptlrpcd_00_00:12056] [56376. Finally, this document explains the stall detector’s “splat” format. Aligns the output of the last line of RCU stall. 900000 PCI: Using ACPI for IRQ routing 61. The issue occurrence is random but exists. debugging rcu stalls The ultimate action-packed science and technology magazine bursting with exciting information about the universe Subscribe today for our Black Frida offer - Save up to 50% Engaging articles, amazing illustrations & exclusive interviews Issues delivered straight to your door or device. Update comments and document. 733084] rcu: blocking rcu_node structures (internal RCU debug): [ 29. This document first discusses what sorts of issues RCU’s CPU stall detector can locate, and then discusses kernel parameters and Kconfig options that can be used to fine-tune the detector’s operation. Web. Update comments and document. Web. h > index 96122f203187f39. This time period is normally 20 milliseconds on Android devices. Thanks to Elliott, Robert for the test. + bool "Provide additional rcu stall debug information" + depends on RCU_STALL_COMMON + default n + help + Statistics during the period from RCU_CPU_STALL_TIMEOUT/2 to + RCU_CPU_STALL_TIMEOUT, such as the number of (hard interrupts, soft + interrupts, task switches) and the cputime of (hard interrupts, soft. 5-linode48 #1 Call Trace: 0 forum:zunzun 9 years, 11 months ago After a recent reboot, I see high CPU for a process named rcu_sched. > > > > v2 --> v3: > > 1. 000000] Inode-cache hash table entries: 262144 (order: 9, 2097152 bytes) [ 0. rcu_cpu_stall_suppress module parameter disables RCU’s CPU stall detector, which detects conditions that unduly delay RCU grace periods. But my observation is that will be less to occur while lower CPU idle (CPU busy). TDA4VM: rcu: INFO: rcu_preempt detected stalls on CPUs fengying li Prodigy 170 points Part Number: TDA4VM hi TI When system run long time the system will abnormal, our SDK version is 08. 123 with Imx6Q processor, we are getting rcu_preempt error and cpu hangs, The HW doesnt have HDMI or any on screen dispay, however the device had configurations and device tree for, GPU and HDMI enabled. A third fix, which works only if this code does > >not use RCU and does not invoke any code that does use RCU, is to tell > >RCU that it should ignore this code (which will require a little work > >on RCU, as it currently does not tolerate this sort of thing aside from > >the idle threads). Change "rcu stall" to "RCU stall". org> Subject: IP27: debugging RCU stalls under newer code: From: Joshua Kinard <kumba@gentoo. Using the latest versions of kernels and inits I get the following repeating indefinitely: rcu: INFO: rcu_sched self-detected stall on CPU rcu: 0-. When there are more than two continuous RCU stallings, correctly handle the value of the second and subsequent sampling periods. CCing LMKL and linux-rt-users in case anyone else is seeing this. */ int sysctl_panic_on_rcu_stall __read_mostly; int sysctl_max_rcu_stall_to_panic __read_mostly; #ifdef CONFIG_PROVE_RCU #define RCU_STALL_DELAY_DELTA (5 * HZ) #else #define RCU_STALL_DELAY_DELTA 0 #endif #define RCU_STALL_MIGHT_DIV 8 #define RCU_STALL_MIGHT_MIN (2 * HZ) int rcu_exp_jiffies_till_stall_check(void. Uplock Roller (RG) Warning cam. Aligns the output of the last line of RCU stall. Please note that PREEMPT_RCU builds can be stalled by tasks as well as by CPUs, and that the tasks will be indicated by PID, for example, “P3421”. Update comments and document. 000000] Kernel command line: earlycon console=ttyPS0,115200 clk_ignore_unused root=/dev/mmcblk1p2 rw rootwait [ 0. Web. You are minding your own business when suddenly one of your system splats out something like "INFO: rcu_bh_state detected stalls on CPUs/tasks: { 3 5 } (detected by 2, 2502 jiffies)". The project is very urgent, please give support！. 000000] Kernel command line: earlycon console=ttyPS0,115200 clk_ignore_unused root=/dev/mmcblk1p2 rw rootwait [ 0. 62 Beta BSP. Change "rcu stall" to "RCU stall". from [Joshua Kinard] [Permanent Link] To: Linux/MIPS <linux-mips@linux-mips. de> wrote:. panic_on_rcu_stall parameter added to sysctl to debug RCU stalls on a vmcore. From the documentation about RCU stall detector: The following problems can result in RCU CPU stall warnings:. This message indicates that CPU 32 detected that CPUs 2 and 16 were both causing stalls, and that the stall was affecting RCU-sched. Rope trick. 13 09/46] rcu/tree: Handle VM stoppage in stall detection Date: Sun, 5 Sep 2021 21:20:14 -0400 [thread overview] Message-ID: <20210906012052. 000000] software IO TLB: mapped [mem 0x7bfff000. OK, let's take a look at the stall warning. The kernel includes an RCU stall detection. Any help or suggestions would be greatly appreciated. Debugging Linux issues with eBPF One incident from start to finish with dynamic tracing applied. System logs: Jul 28 04:24:10 kernel: INFO: rcu_sched self-detected stall on CPU Jul 28 04:24:10 kernel: INFO: rcu_sched det. Finally, this document explains the stall detector’s “splat” format. Attached Logs for more information: [285165. from [Joshua Kinard] [Permanent Link] To: Linux/MIPS <linux-mips@linux-mips. And as we all know, evolutionary forces are driven by random changes, which absolutely anyone could make. Rear seat removal. We've seen RCU stalls before, and our (suboptimal) solution was to . 173525] NMI watchdog: Watchdog detected hard LOCKUP on cpu 10 [ 5653. Update comments and document. See Documentation/acpi/debug. Change "rcu stall" to "RCU stall". A hard lockup is encountered and then the kernel crashes in the end. Ivan Babrou Performance @ Cloudflare. But if you're going to provide the > > > RCU-flavor integers, they should be in RCU itself and refer to RCU > > > flavors, rather than being in rcutorture and refering to test types. > > > > Fair enough, will take that approach! > > > > I am thinking in terms of something like the following: > > > > RCU_FLAVOR > > RCU_BH_FLAVOR > > RCU_SCHED. The panic_on_rcu_stall interface is useful for defining the root cause of RCU . detector, which detects conditions that unduly delay RCU grace periods. Aligns the output of the last line of RCU stall. set rcu_cpu_stall_suppress = 1 Helpful Unhelpful. arm, arm64: rcu_preempt self-detected stall. A hard lockup is encountered and then the kernel crashes in the end. Please note that PREEMPT_RCU builds can be stalled by tasks as well as by CPUs, and that the tasks will be indicated by PID, for example, “P3421”. Web. The next question is "What caused it?. Using RCU’s CPU Stall Detector. v1: In some extreme cases, such as the I/O pressure test, the CPU usage may be 100%, causing RCU stall. 8 ມ. Web. Add Kconfig option CONFIG_RCU_CPU_STALL_DEEP_DEBUG and boot parameter rcupdate. 16 ມ. RCU Concepts. Note that certain high-overhead debugging options, for example the function_graph tracer, can result in interrupt handler taking considerably longer than normal, which can in turn result in RCU CPU stall warnings. Image: haos_ova-7. Web. Web. A hard lockup is encountered and then the kernel crashes in the end. 19 ພ. Change "rcu stall" to "RCU stall". Kernel crashed due to a hard LOCKUP on CPU#10: [ 5653. Web. The kernel is preempt-rt kernel. This problem really has happened, and seems to be most likely to result in RCU CPU stall warnings for CONFIG_NO_HZ_COMMON=n kernels. Fix the return type of kstat_cpu_irqs_sum () 2. Resolve a git am conflict. Fix the return type of kstat_cpu_irqs_sum () 2. Aligns the output of the last line of RCU stall. In this case, the printed information about current is not useful. com, ardb-AT. In the vast majority of cases, real-time users face RCU stalls due to the delay of RCU callbacks execution. Anyway, your thread seems to have been held up for 59 seconds (assuming a 250 hertz kernel). Both causes are likely on Virtual Machines. Using RCU’s CPU Stall Detector. Using RCU’s CPU Stall Detector. The RCU callbacks are responsible for performing the necessary RCU work to achieve the end of a grace period. Git Cloned the linux-xlnx repository,build the kernel and created an image. Using the latest versions of kernels and inits I get the following repeating indefinitely: rcu: INFO: rcu_sched self-detected stall on CPU rcu: 0-. hypnopimp, sikp the game
The stall detector's idea of what constitutes "unduly delayed" is. . Debugging rcu stalls
Displays the number and usage of hard interrupts, soft interrupts, and context switches that are generated within half of the CPU stall timeout, can help us make a general judgment. ub with mkimage from. Fix the return type of kstat_cpu_irqs_sum () 2. > 3. For example, RCU stall warnings occurs in one hour while CPU idle>90%. Add Kconfig option CONFIG_RCU_CPU_STALL_DEEP_DEBUG and boot parameter > rcupdate. 000000] Dentry cache hash table entries: 524288 (order: 10, 4194304 bytes) [ 0. Web. Thanks to Elliott, Robert for the test. Resolve a git am conflict. Thanks to Elliott, Robert for the test. Debugging rcu stalls. Most recently Seen. > > v5 --> v6: > 1. Fine-Tuning the RCU CPU Stall Detector The rcuupdate. When there are more than two continuous RCU stallings, correctly handle the value of the second and subsequent sampling periods. > (3) The statistics can be accurate to a single hard interrupt, software > interrupt, or task. Feb 15, 2016 · 2 Answers Sorted by: 3 Yes, continuous using of CPU from a high priority thread for a long time (1ms is a large period from the view of scheduler) could be a reason of RCU stall. EFI: Enabled. Please note that PREEMPT_RCU builds can be stalled by tasks as well as by CPUs, and that the tasks will be indicated by PID, for example, “P3421”. h> #include <string. This added debugging information is suppressed by default and can be enabled by building the kernel with CONFIG_RCU_CPU_STALL_CPUTIME=y or by booting with rcupdate. Both causes are likely on Virtual Machines. They have also tried applying: e97a32a5a3bc ("rcu: Do RCU GP kthread self-wakeup from softirq and interrupt") Any suggestions/help are appreciated. Update comments and document. Feb 15, 2016 · 2 Answers Sorted by: 3 Yes, continuous using of CPU from a high priority thread for a long time (1ms is a large period from the view of scheduler) could be a reason of RCU stall. v5 --> v6: 1. : (3 GPs behind) idle=ec7/140000000000000/ softirq=76321963/. And one approach is to take a less aggressive RCU CPU stall timeout, say reducing from 21 seconds to (say) 15 seconds instead of all the way down to 20 milliseconds. 22 ພ. Hi, We are doing thermal testing for our custom boards at -20 degree Celsius temperature. 30 ສ. The RCU callbacks are responsible for performing the necessary RCU work to achieve the end of a grace period. RCU bugs can often be debugged with the help of CONFIG_RCU_TRACE. When there are more than two continuous RCU stallings, correctly handle the value of the second and subsequent sampling periods. 979162] NMI watchdog: BUG: soft lockup - CPU#26 stuck for 23s! [ptlrpcd_00_00:12056] [56376. Web. Sometimes we observe RCU stall warnings immediately after device boots up and sometimes we observe after running the device for longs hours (> 12 hours). 19 ພ. 900000 INFO: rcu_sched_state detected stall on CPU 0, when booting on Xen. Finally, this document explains the stall detector’s “splat” format. Rear seat removal. Although a RCU Stall can be a side effect of a kernel BUG, this is not the typical case for the real-time kernel users. This condition can result in RCU-sched and RCU-bh stalls. Uplock Roller (RG) Warning cam. one of those rare RCU bugs for which a debugger might be helpful. Nov 11, 2022 · 3. 000000] Dentry cache hash table entries: 524288 (order: 10, 4194304 bytes) [ 0. debugging rcu stalls The ultimate action-packed science and technology magazine bursting with exciting information about the universe Subscribe today for our Black Frida offer - Save up to 50% Engaging articles, amazing illustrations & exclusive interviews Issues delivered straight to your door or device. 98 fixes the problem. McKenney 0 siblings, 1 reply; 2+ messages in thread From: Zqiang @ 2022-05-18 11:43 UTC (permalink / raw) To: paulmck, frederic; +Cc: rcu, linux-kernel This commit adds a "D" indicator to expedited RCU. Change "rcu stall" to "RCU stall". I am having the same problem on Ultra96 V1 Board. 23 ມ. This occurs due to the starvation of the rcuc/ threads, that runs with priority FIFO:2. Sometimes we observe RCU stall warnings immediately after device boots up and sometimes we observe after running the device for longs hours (> 12 hours). Aligns the output of the last line of RCU stall. Add Kconfig option CONFIG_RCU_CPU_STALL_DEEP_DEBUG and boot parameter rcupdate. perf_fuzzer, Mark Rutland, Vince Weaver. Kernel hard LOCKUP and rcu_sched stalls caused by a slow responding serial console interface This document (000020516) is provided subject to the disclaimer at the end of this document. McKenney 0 siblings, 1 reply; 2+ messages in thread From: Zqiang @ 2022-05-18 11:43 UTC (permalink / raw) To: paulmck, frederic; +Cc: rcu, linux-kernel This commit adds a "D" indicator to expedited RCU. In the vast majority of cases, real-time users face RCU stalls due to the delay of RCU callbacks execution. panic_on_rcu_stall parameter added to sysctl to debug RCU stalls on a vmcore. 9 to 4. Thanks to Elliott, Robert for the test. v4 --> v5: 1. Using RCU’s CPU Stall Detector. Kernel hard LOCKUP and rcu_sched stalls caused by a slow responding serial console interface This document (000020516) is provided subject to the disclaimer at the end of this document. Aligns the output of the last line of RCU stall. Both causes are likely on Virtual Machines. txt for more information about debug layers and. + bool "Provide additional rcu stall debug information" + depends on RCU_STALL_COMMON + default n + help + Statistics during the period from RCU_CPU_STALL_TIMEOUT/2 to + RCU_CPU_STALL_TIMEOUT, such as the number of (hard interrupts, soft + interrupts, task switches) and the cputime of (hard interrupts, soft. rcu_cpu_stall_suppress module parameter disables RCU’s CPU stall detector, which detects conditions that unduly delay RCU grace periods. 3. When there are more than two continuous RCU stallings, correctly handle the value of the second and subsequent sampling periods. Change "rcu stall" to "RCU stall". Web. Sometimes we observe RCU stall warnings immediately after device boots up and sometimes we observe after running the device for longs hours (> 12 hours). What Causes RCU CPU Stall Warnings?¶ So your kernel printed an RCU CPU stall warning. > 3. Add Kconfig option CONFIG_RCU_CPU_STALL_DEEP_DEBUG and boot parameter rcupdate. The project is very urgent, please give support！. The RCU callbacks are responsible for performing the necessary RCU work to achieve the end of a grace period. 12 with some local. org>, Sasha Levin <sashal@kernel. Nov 11, 2022 · 2. debug | 13 +++ kernel/rcu/rcu. This example of stall. Web. Although a RCU Stall can be a side effect of a kernel BUG, this is not the typical case for the real-time kernel users. Either way, the: system will eventually run out of memory and hang. 28 ມ. 413326] all qses seen, last rcu_sched kthread activity 6233 (4295220632-4295214399), jiffies_till_next_fqs=2, root ->qsmask 0x0. 62 Beta BSP. 462843] 13-. When returning from the kernel debugger allow a reset of the rcu jiffies_stall value to prevent the rcu stall detector from sending NMI events which stack dumps on all the cpus in the system. 62 Beta BSP. When there are more than two continuous RCU stallings, correctly handle the value of the second and subsequent sampling periods. Using RCU’s CPU Stall Detector ¶. 000000] Inode-cache hash table entries: 262144 (order: 9, 2097152 bytes) [ 0. Web. Fix the return type of kstat_cpu_irqs_sum () 2. 979162] NMI watchdog: BUG: soft lockup - CPU#26 stuck for 23s! [ptlrpcd_00_00:12056] [56376. For debugging CPU saturation issues, we call on perf to fish out. > (2) Do you mean to suppress such new debugging information that I added? > or the whole RCU stall information? Only the new debugging information. Update comments and document. Most recently Seen. 1 Answer Sorted by: 1 A jiffi is the basic unit of measure within the kernel, or the tick rate. v1: In some extreme cases, such as the I/O pressure test, the CPU usage may be 100%, causing RCU stall. When there are more than two continuous RCU stallings, correctly handle the value of the second and subsequent sampling periods. In our custom board with Linux kernel 4. ^permalinkrawreply[flat|nested] 5+ messages in thread. Web. The next question is “What caused it?” The following problems can result in RCU CPU stall warnings: A CPU looping in an RCU read-side critical section. Jun 06, 2022 · Hi, I am getting occasionally kernels hanging (sometimes hours after boot) with the following output occurring and that just goes on until i reboot the machine: INFO: rcu_sched self-detected stall on CPU 1-. Move the start point of statistics from rcu_stall_kick_kthreads() to rcu_implicit_dynticks_qs(), removing the dependency on irq_work. RCU Concepts. v5 --> v6: 1. Web. 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