Perfetto Trace for 'sched_blocked_reason' BUT Found No Blocking Functions

Question

I am attempting to capture some performance issues(with Perfetto) using the following configuration:

data_sources: 
{
     config {
         name: "linux.ftrace"
         ftrace_config {
             ftrace_events: "sched/sched_blocked_reason" 
 ...

However, the results I obtained are as follows(lots of, but none of them contain BLOCK FUNCTIONS):

00:00:05.959445920 sched_blocked_reason 2 irq/51-meson-am irq/51_meson_am-2160 ( 2160) [002] .... 2796.096890: sched_blocked_reason: pid=4821 io_wait=0 caller=2

Any idea? Could anyone provide any insights into this output? Specifically, I’m looking to understand the sched_blocked_reason event and its implications for system performance.

Thank you for your assistance.

Additionally, I recall that searching for sched_blocked_reason within atrace can help identify the blocking functions. Can't I get same thing from Perfetto?

Answer 1

Found that I should use symbolize_ksyms: true in ftrace config, that help. eg:

data_sources: {
    config {
        name: "linux.ftrace"
        ftrace_config {
            ftrace_events: "ext4/*"
            ftrace_events: "sched/sched_blocked_reason"
            symbolize_ksyms: true
        }
    }
}