Dear community, I wish to ask you some clarifications about the format of two ftrace events: `funcgraph_entry` and `funcgraph_exit`, basically those in `$ANY_DEBUG_FS/tracing/events/ftrace`. Let me copy and paste them here: # cat funcgraph_entry/format name: funcgraph_entry ID: 11 format: field:unsigned short common_type; offset:0; size:2; signed:0; field:unsigned char common_flags; offset:2; size:1; signed:0; field:unsigned char common_preempt_count; offset:3; size:1; signed:0; field:int common_pid; offset:4; size:4; signed:1; field:unsigned long func; offset:8; size:8; signed:0; field:int depth; offset:16; size:4; signed:1; print fmt: "--> %ps (%d)", (void *)REC->func, REC->depth AND # cat funcgraph_exit/format name: funcgraph_exit ID: 10 format: field:unsigned short common_type; offset:0; size:2; signed:0; field:unsigned char common_flags; offset:2; size:1; signed:0; field:unsigned char common_preempt_count; offset:3; size:1; signed:0; field:int common_pid; offset:4; size:4; signed:1; field:unsigned long func; offset:8; size:8; signed:0; field:int depth; offset:16; size:4; signed:1; field:unsigned int overrun; offset:20; size:4; signed:0; field:unsigned long long calltime; offset:24; size:8; signed:0; field:unsigned long long rettime; offset:32; size:8; signed:0; print fmt: "<-- %ps (%d) (start: %llx end: %llx) over: %d", (void *)REC->func, REC->depth, REC->calltime, REC->rettime, REC->depth While writing a `trace.dat`, I know that all the entries have an header, described by the Linux ringbuffer format (file `header_event`): # compressed entry header type_len : 5 bits time_delta : 27 bits array : 32 bits padding : type == 29 time_extend : type == 30 time_stamp : type == 31 data max type_len == 28 Such header includes a timestamp (that can be a delta of the timestamp present in the `header_page`). I have one question for the ftrace's community: Why are the following fields of a `funcgraph_exit` entry useful? ` calltime` and ` rettime`. They look like redundant for me, because the timing information is already present on the `header_event`. Please can you clarify me whether I am wrong? Best Regards && have lovely holidays, Matteo
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