How to write mpykdump extension

If you are dealing with a vmcore (Linux memory dump), you must be familiar with ‘crash’. It is a powerful tool, but it doesn’t cover all the data you can find in Linux kernel. So, there comes ‘mpykdump’ which is a crash extension which understands python code. mpykdump comes with many prebuilt commands that youContinue reading “How to write mpykdump extension”

Print callgraph of a function

Sometimes you may want to see what functions are called in a function in multiple level. Below command in my extension may help. crash> edis -c irq_exit {irq_exit} -+- {rcu_irq_exit} -+- {warn_slowpath_null} |- {idle_cpu} |- {tick_nohz_stop_sched_tick} -+- {ktime_get} | |- {update_ts_time_stats} | |- {sched_clock_idle_sleep_event} | |- {rcu_needs_cpu} | |- {select_nohz_load_balancer} | |- {rcu_enter_nohz} | |-Continue reading “Print callgraph of a function”

An example case with some of my commands

System got high load average and it wasn’t responding for long which is a typical hang situation. It shows total 56 tasks in D (Uninterruptible) state and 5 tasks were in D state longer than 120 seconds which is considered as a hung task. Let’s see what it was waiting for in this process. Alright,Continue reading “An example case with some of my commands”