Re: perf: user-space trace decoding

Hi Bharat,

On Tue, Nov 05, 2019 at 08:30:25AM +0000, Bharat Bhushan wrote:

Hi All,

Linux h/w trace decoding is working as expected but user-space trace decoding not showing sybmols (dump raw trace shows h/w trace info) of user-space application/libraries.

Here is how I am using:

1. Kernel trace => perf record -C 1 -e cs_etm/@tmc_etr1/k taskset 0x2 uname

   => tar czf cs_example.tgz perf.data .debug

   Transfer cs_example.tgz on x86 machine, untar, copy .debug in ~/ (home) => perf report --vmlinux=./vmlinux

   # Samples: 937  of event 'branches:k'
   # Event count (approx.): 937
   #
   # Children      Self  Command  Shared Object      Symbol                                        
   # ........  ........  .......  .................  ..............................................
   #
       15.58%    15.58%  swapper  [kernel.kallsyms]  [k] __delay
        8.54%     8.54%  swapper  [kernel.kallsyms]  [k] arch_counter_get_cntpct
        3.31%     3.31%  swapper  [kernel.kallsyms]  [k] event_sched_in.isra.37
        2.67%     2.67%  swapper  [kernel.kallsyms]  [k] group_sched_in
        2.56%     2.56%  swapper  [kernel.kallsyms]  [k] do_idle
        2.35%     2.35%  swapper  [kernel.kallsyms]  [k] perf_event_update_userpage
        2.24%     2.24%  swapper  [kernel.kallsyms]  [k] clocks_calc_mult_shift
   
   

2. User-space trace

   => perf record -C 1 -e cs_etm/@tmc_etr1/u taskset 0x2 uname

I verified this command on DB410c, it can record and report well.

=> tar czf cs_example.tgz perf.data .debug

  Transfer cs_example.tgz on x86 machine, untar, copy .debug in ~/ (home)
=> perf report
       Error:
       The perf.data data has no samples!
       # To display the perf.data header info, please use --header/--header-only options.
      #
But if dump raw trace then I can see ISYNC/ATOM packets

One potential reason is perf cannot find the correct DSO file. Could you use below command to output more verbose log?

# perf --debug verbose=10 report --stdio > perf_report_dbg.log

Maybe can find more hints for this failure.

Thanks, Leo Yan

=> perf report --dump
. ... CoreSight ETM Trace data: size 25960 bytes
    Idx:24; ID:12;  I_ASYNC : Alignment Synchronisation.
    Idx:36; ID:12;  I_TRACE_INFO : Trace Info.; INFO=0x0
    Idx:39; ID:12;  I_TRACE_ON : Trace On.
    Idx:40; ID:12;  I_CTXT : Context Packet.; Ctxt: AArch64,EL2, NS; CID=0x00000000; 
    Idx:46; ID:12;  I_TRACE_ON : Trace On.
    Idx:47; ID:12;  I_CTXT : Context Packet.; Ctxt: AArch64,EL0, NS; CID=0x00000000; 
    Idx:53; ID:12;  I_ADDR_L_64IS0 : Address, Long, 64 bit, IS0.; Addr=0x0000FFFF801CCF7C; 
    Idx:62; ID:12;  I_ATOM_F1 : Atom format 1.; N
    Idx:63; ID:12;  I_TIMESTAMP : Timestamp.; Updated val = 0xede4824ce5
    . . . 

Any idea what I am missing.

Thanks -Bharat _______________________________________________ CoreSight mailing list CoreSight@lists.linaro.org https://lists.linaro.org/mailman/listinfo/coresight