On Sat, 2022-05-07 at 08:02 +0300, Tzvetomir Stoyanov wrote:
> On Fri, May 6, 2022 at 7:18 PM christopher lee
> <christopher.lee.eu@xxxxxxxxx> wrote:
> >
> > Hi all,
> >
> > I use libtraceevent in my trace tool to parse the event log. Now I
> > allocated an instance, but no idea how to use
> > tep_register_event_handler() to register a handler for the
> > instance. Is
> > it possilbe to register handler for the event in the instance?
> >
>
> Hi Chrit,
> All trace events are the same across all trace instances, thus the
> handler registered with tep_register_event_handler() handles events
> from all instances with a given id. That's why there are no
> "instance"
> oriented APIs in that library. I would suggest looking at the tracefs
> library, which is instance aware. It can be used to allocate trace
> instances and read events from a given instance.
>
> https://trace-cmd.org/Documentation/libtracefs/
>
Hi Tzvetomir Stoyanov,
Thanks, instance event handlers work now, but I'm confused with these
codes, do I have to read trace_pipe_raw? I found that if I didn't read
this file, the handler would not be able to get trace information.
Becuase if I read this file, and also call tep_print_event() will
consume lots of CPU resoruce. how can I parse the trace event info
without reading this file?
for (i = 0; ; i++) {
char *raw_buf;
char *cpu;
ret = asprintf(&cpu, "%s/cpu%d", per_cpu, i);
if (ret < 0)
pdie("Could not allocate memory for cpu buffer
%d name", i);
ret = stat(cpu, &st);
if (ret < 0 || !S_ISDIR(st.st_mode)) {
free(cpu);
goto start;
}
ret = asprintf(&raw_buf, "%s/trace_pipe_raw", cpu);
if (ret < 0)
pdie("Could not allocate memory for cpu %d raw
buffer name", i);
read_raw_buffer(i, raw_buf);
free(raw_buf);
free(cpu);
}
Best regards,
Christ
>
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