• Lingutla Chandrasekhar's avatar
    softirq: Add trace points for tasklet entry/exit · f4bf3ca2
    Lingutla Chandrasekhar authored
    Tasklets are supposed to finish their work quickly and should not block the
    current running process, but it is not guaranteed that they do so.
    
    Currently softirq_entry/exit can be used to analyse the total tasklets
    execution time, but that's not helpful to track individual tasklets
    execution time. That makes it hard to identify tasklet functions, which
    take more time than expected.
    
    Add tasklet_entry/exit trace point support to track individual tasklet
    execution.
    
    Trivial usage example:
       # echo 1 > /sys/kernel/debug/tracing/events/irq/tasklet_entry/enable
       # echo 1 > /sys/kernel/debug/tracing/events/irq/tasklet_exit/enable
       # cat /sys/kernel/debug/tracing/trace
     # tracer: nop
     #
     # entries-in-buffer/entries-written: 4/4   #P:4
     #
     #                                _-----=> irqs-off/BH-disabled
     #                               / _----=> need-resched
     #                              | / _---=> hardirq/softirq
     #                              || / _--=> preempt-depth
     #                              ||| / _-=> migrate-disable
     #                              |||| /     delay
     #           TASK-PID     CPU#  |||||  TIMESTAMP  FUNCTION
     #              | |         |   |||||     |         |
               <idle>-0       [003] ..s1.   314.011428: tasklet_entry: tasklet=0xffffa01ef8db2740 function=tcp_tasklet_func
               <idle>-0       [003] ..s1.   314.011432: tasklet_exit: tasklet=0xffffa01ef8db2740 function=tcp_tasklet_func
               <idle>-0       [003] ..s1.   314.017369: tasklet_entry: tasklet=0xffffa01ef8db2740 function=tcp_tasklet_func
               <idle>-0       [003] ..s1.   314.017371: tasklet_exit: tasklet=0xffffa01ef8db2740 function=tcp_tasklet_func
    Signed-off-by: default avatarLingutla Chandrasekhar <clingutla@codeaurora.org>
    Signed-off-by: default avatarJ. Avila <elavila@google.com>
    Signed-off-by: default avatarJohn Stultz <jstultz@google.com>
    Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
    Reviewed-by: default avatarSteven Rostedt (Google) <rostedt@goodmis.org>
    Link: https://lore.kernel.org/r/20230407230526.1685443-1-jstultz@google.com
    
    [elavila: Port to android-mainline]
    [jstultz: Rebased to upstream, cut unused trace points, added
     comments for the tracepoints, reworded commit]
    f4bf3ca2
irq.h 4.71 KB