Re: [PATCH RFC V8 3/4] perf,tools: per-event callgraph support

[Jiri Olsa]

On Tue, Aug 04, 2015 at 04:30:21AM -0400, Kan Liang wrote:

SNIP

> +
> +     /* User explicitly set per-event callgraph, clear the old setting and 
> reset. */
> +     if ((callgraph_buf != NULL) || (dump_size > 0)) {
> +
> +             /* parse callgraph parameters */
> +             if (callgraph_buf != NULL) {
> +                     if (!strcmp(callgraph_buf, "no")) {
> +                             param.enabled = false;
> +                             param.record_mode = CALLCHAIN_NONE;
> +                     } else {
> +                             param.enabled = true;
> +                             if (parse_callchain_record_opt(callgraph_buf, 
> &param)) {
> +                                     pr_err("per-event callgraph setting for 
> %s failed. "
> +                                            "Apply callgraph global setting 
> for it\n",
> +                                            evsel->name);
> +                                     return;
> +                             }
> +                     }
> +             }
> +             if (dump_size > 0)
> +                     param.dump_size = dump_size;

the parse_callchain_record_opt does some rounding on the stack size value
via the get_stack_size function, so following command like does not fail:

  $ perf record --call-graph='dwarf,819' ls

while the term syntax fails:
  $ perf record -e 'cpu/cpu-cycles,call-graph=dwarf,stack-size=819/

  Error:
  The sys_perf_event_open() syscall returned with 22 (Invalid argument) for 
event (cpu/cpu-cycles,time=0,call-graph=dwarf,stack-size=819/).
  /bin/dmesg may provide additional information.
  No CONFIG_PERF_EVENTS=y kernel support configured?


jirka
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