On Mon, Mar 23, 2020 at 07:48:26AM +0430, ahmadkhorrami wrote: > Here is a link to the detailed question at Stackoverflow: > > https://stackoverflow.com/questions/60766026/wrong-perf-backtraces hi, what perf version are you running? jirka > > I can copy it here, if needed. > > Thanks > > On 2020-03-23 05:04, Steven Rostedt wrote: > > > On Mon, 23 Mar 2020 00:54:01 +0430 > > ahmadkhorrami <ahmadkhorrami@xxxxxxxx> wrote: > > > >> Hi, > >> I used "Perf" to extract call graphs in an evince benchmark. The command > >> used is as follows: > >> sudo perf record -d --call-graph dwarf -c 10000 e > >> mem_load_uops_retired.l3_miss:uppp /opt/evince-3.28.4/bin/evince > >> > >> I extracted the backtraces using "perf script" and found out that there > >> are many corrupted backtrace instances. Some contained repeated function > >> calls, for example two consecutive gmallocn()s exactly at the same > >> offsets. There are also some backtraces where the callers and callees do > >> not match. > > > > Could you show some examples of the backtraces you mention? > > > >> Note that that mappings are correct. In other words, each single line of > >> the reported backtraces is correct (i.e., addresses match with > >> functions). But is seems that there are some function calls in the > >> middle, which are missed by "Perf". Strangely, in all runs (and also > >> with different sampling frequencies) the problem occurs exactly at the > >> same place. > >> > >> I am really confused and looking forward to any help. I can also send > >> backtraces if needed. > > > > -- Steve
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