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Questions tagged [ftrace]

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Change format of syscall event trace output to ftrace

I enabled ftrace event tracing for sys_enter_openat syscall. The respective output format given at events/syscalls/sys_enter_openat/format is print fmt: "dfd: 0x%08lx, filename: 0x%08lx, flags: 0x%...
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0answers
18 views

Performance reduction activating trace-functionality in kernel

Is there any performance reduction to be expected from just activating trace (ftrace) functionality in the Linux kernel, but not using it at run time?
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0answers
16 views

functions folder in trace_stat folder of ftrace

I am learning ftrace, I read from the following link that I can enable function profiling using the 'function_profile_enabled' file. mount -t tracefs nodev /sys/kernel/tracing cd /sys/kernel/tracing ...
1
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0answers
229 views

how to use ftrace to function_trace a kernel modules interrupt?

I have a Banana Pi Arm device with 2 cores (1.2 GHz) running a Debian kernel which I enabled ftrace kernel debug options. I want to determine the amount of time spent in a kernel module function. The ...
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0answers
37 views

How does Ftrace resolve symbols when KASLR is enabled?

Ftrace seems to be able to resolve symbols from address even with kaslr enabled. How does it resolve it? Does it use physical address or virtual address? Can you give the direct referencce to the ...
1
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0answers
67 views

Tool for displaying timeline view of kernel/userspace execution trace

I've used the ftrace tool trace-cmd for recording scheduling tracepoints and syscall tracepoints. I can inspect them visually using the kernelshark GUI program. It dislays per-core timelines and per-...
1
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0answers
26 views

PMU and tracepoints

I am searching for information about the mechanism of creation of tracepoints. From this topic What are Kernel PMU event-s in perf_events list? and this blog brendangregg I've got that tracepoints are ...
1
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0answers
123 views

Function profiling on multi-core platform for specific PID using ftrace

I'm trying to use ftrace for function profiling based on function_profile_enabled as described here. I would like to capture function calls only for a certain PID using set_ftrace_pid as described in ...
3
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1answer
129 views

Ftrace time duration

I echoed 1 to tracing_on in /sys/kernel/debug/tracing directory and echoed 0 again after a second. However, the timestamp of the first entry is 216.852 and that of the last entry is 234.136 giving me ...
0
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1answer
522 views

ftrace not working? Probably a simple mistake

I am trying to monitor the function pci_bus_write_config_byte. I have a kernel module that I know for certain calls that function. echo "pci_bus_write_config_byte" > set_ftrace_filter Then I did ...
0
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1answer
545 views

How to get epoch time with trace-cmd (frontend for ftrace)?

<...>-32578 [001] **133767.868869**: kfree: call_site=ffffffff810e6f06 ptr=(nil) How to make trace-cmd report time in epoch time? The time by default is I think time since ...
6
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1answer
2k views

filter out certain processes and/or pids in ftrace?

I'm not sure if I'm thinking about this the right way (and please correct me if I'm wrong), but the following is my understanding of ftrace. In /sys/kernel/debug/tracing, there are the following ...