lkml.org 
[lkml]   [2015]   [Nov]   [20]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [RFC/PATCH] perf tools: Introduce perf_thread for backtrace
On Fri, Nov 20, 2015 at 03:03:03PM +0900, Namhyung Kim wrote:
> Backtrace is a crucial info for debugging. And upcoming refcnt
> tracking facility also wants to use it.
>
> So instead of relying on glibc's backtrace_symbols[_fd] which misses
> some (static) functions , use our own symbol searching mechanism. To
> do that, add perf_thread global variable to keep its maps and symbols.
>
> The backtrace output from TUI is changed like below. (I made a key
> action to generate a segfault for testing):
>
> Before:
> perf: Segmentation fault
> -------- backtrace --------
> perf[0x544a8b]
> /usr/lib/libc.so.6(+0x33680)[0x7fc46420b680]
> perf[0x54041b]
> perf(perf_evlist__tui_browse_hists+0x91)[0x5432e1]
> perf(cmd_report+0x1d20)[0x43cb10]
> perf[0x487073]
> perf(main+0x62f)[0x42cb1f]
> /usr/lib/libc.so.6(__libc_start_main+0xf0)[0x7fc4641f8610]
> perf(_start+0x29)[0x42cc39]
> [0x0]
>
> After:
> perf: Segmentation fault
> -------- backtrace --------
> perf_evsel__hists_browse(+0x43b) in perf [0x54066b]
> perf_evlist__tui_browse_hists(+0x91) in perf [0x543531]
> cmd_report(+0x1d20) in perf [0x43cb50]
> run_builtin(+0x53) in perf [0x4870b3]
> main(+0x634) in perf [0x42cb54]
> __libc_start_main(+0xf0) in libc-2.22.so [0x7fea3577c610]
> _start(+0x29) in perf [0x42cc79]
> [0x0]

nice idea!

SNIP

> +
> +void create_perf_thread(void)
> +{
> + struct perf_tool tool = {
> + .comm = perf_event__process_comm,
> + .mmap = perf_event__process_mmap,
> + .mmap2 = perf_event__process_mmap2,
> + };
> + struct thread_map *tm;
> + struct machine *machine;
> + int pid = getpid();
> +
> + machine = machine__new_host();
> + if (machine == NULL)
> + return;
> +
> + tm = thread_map__new_dummy();
> + if (tm == NULL) {
> + machine__delete(machine);
> + return;
> + }

I think we could treat errors the usual way in here..
if fail to alloc this early, something is terribly wrong anyway

jirka


\
 
 \ /
  Last update: 2015-11-20 11:01    [W:0.112 / U:0.152 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site