On 2022/11/22 6:29, Paul E. McKenney wrote: > On Sat, Nov 19, 2022 at 05:25:02PM +0800, Zhen Lei wrote: >> v7 --> v8: >> 1. Change call jiffies64_to_msecs() to call jiffies_to_msecs(). >> 2. Mention that rcupdate.rcu_cpu_stall_cputime overrides >> CONFIG_RCU_CPU_STALL_CPUTIME behaviour in the Kconfig help text. >> 3. Fix a make htmldocs warning, change "|...|" to ":...:". >> >> v6 --> v7: >> 1. Use kcpustat_field() to obtain the cputime. >> 2. Make the output start with "\t" to match other related prints. >> 3. Aligns the output of the last line of RCU stall. >> >> v5 --> v6: >> 1. When there are more than two continuous RCU stallings, correctly handle the >> value of the second and subsequent sampling periods. Update comments and >> document. >> Thanks to Elliott, Robert for the test. >> 2. Change "rcu stall" to "RCU stall". >> >> v4 --> v5: >> 1. Resolve a git am conflict. No code change. >> >> v3 --> v4: >> 1. Rename rcu_cpu_stall_deep_debug to rcu_cpu_stall_cputime. >> >> v2 --> v3: >> 1. Fix the return type of kstat_cpu_irqs_sum() >> 2. Add Kconfig option CONFIG_RCU_CPU_STALL_DEEP_DEBUG and boot parameter >> rcupdate.rcu_cpu_stall_deep_debug. >> 3. Add comments and normalize local variable name >> >> v1 --> v2: >> 1. Fixed a bug in the code. If the rcu stall is detected by another CPU, >> kcpustat_this_cpu cannot be used. >> @@ -451,7 +451,7 @@ static void print_cpu_stat_info(int cpu) >> if (r->gp_seq != rdp->gp_seq) >> return; >> >> - cpustat = kcpustat_this_cpu->cpustat; >> + cpustat = kcpustat_cpu(cpu).cpustat; >> 2. Move the start point of statistics from rcu_stall_kick_kthreads() to >> rcu_implicit_dynticks_qs(), removing the dependency on irq_work. >> >> v1: >> In some extreme cases, such as the I/O pressure test, the CPU usage may >> be 100%, causing RCU stall. In this case, the printed information about >> current is not useful. 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. In other >> cases, we can preliminarily determine whether an infinite loop occurs >> when local_irq, local_bh or preempt is disabled. > > Queued for further review and testing, thank you! > > I did the usual wordsmithing, so please check to see if I messed > something up. Thanks for your help. Sorry, I think I missed a word in the commit message of patch 5/6. This commit documents the additional RCU CPU stall warning output produced - by kernels built with CONFIG_RCU_CPU_STALL_CPUTIME=y. + by kernels built with CONFIG_RCU_CPU_STALL_CPUTIME=y or booted with + rcupdate.rcu_cpu_stall_cputime=1. > > Thanx, Paul > >> Zhen Lei (6): >> genirq: Fix the return type of kstat_cpu_irqs_sum() >> sched: Add helper kstat_cpu_softirqs_sum() >> sched: Add helper nr_context_switches_cpu() >> rcu: Add RCU stall diagnosis information >> doc: Document CONFIG_RCU_CPU_STALL_CPUTIME=y stall information >> rcu: Align the output of RCU stall >> >> Documentation/RCU/stallwarn.rst | 88 +++++++++++++++++++ >> .../admin-guide/kernel-parameters.txt | 6 ++ >> include/linux/kernel_stat.h | 14 ++- >> kernel/rcu/Kconfig.debug | 13 +++ >> kernel/rcu/rcu.h | 1 + >> kernel/rcu/tree.c | 18 ++++ >> kernel/rcu/tree.h | 19 ++++ >> kernel/rcu/tree_stall.h | 35 +++++++- >> kernel/rcu/update.c | 2 + >> kernel/sched/core.c | 5 ++ >> 10 files changed, 198 insertions(+), 3 deletions(-) >> >> -- >> 2.25.1 >> > . > -- Regards, Zhen Lei
