Hello,
On 15 May 2014 07:36, sneha priya <sneha....@hotmail.com> wrote:
> Hello,
>
> There is an issue related to perf which I am facing since 15 days. Hoping
> that the great minds here will help me to solve this.
>
> I have a requirement to make perf tool work on a device having ARM
> architecture. But, on recording the tracepoint events and then running
> ./perf report, it shows the shared objects name as [unknown] and Symbols as
> 00000, whereas for software and hardware events I do not experience this
> issue.
> I have cross compiled the perf tool available on mailine and ported it on a
> device having ARM architecture.
>
> Output on ARM based device with kernel 3.4.
>
> ./perf record -e kmem:kmalloc cal
>
> [ perf record: Woken up 1 times to write data ]
> [ perf record: Captured and wrote 0.007 MB perf.data (~321 samples) ]
>
> ./perf report
>
> Overhead Command Shared Object
> Symbol
> ........................... ................................
> ...........................................
> 40.78% cal [unknown]
> [.]00000000
> 31.6% cal [unknown]
> [.]00000000
>
> [...]
>
> On ubuntu 12.04, system (kernel 3.10) it works perfectly fine.
>
> Output on x86 architecture
>
> ./perf record -e kmem:kmalloc gcalctool
>
> [ perf record: Woken up 3 times to write data ]
> [ perf record: Captured and wrote 0.27 MB perf.data (~845 samples) ]
>
> ./perf report --stdio
>
> Overhead Command Shared
> Object Symbol
> ........................... ................................
> ...........................................
> 96.55% cal
> [kernel.kallsyms] [k] kmem_cache_alloc_trace
> 3.45% cal
> [kernel.kallsyms] [.]__kmalloc
>
> [...]
>
>
> Keenly, awaiting for you help.
There are a few things to check. Note that the 3.4 kernel is OK wrt
perf and tracepoints but is quite old, the recent development now
happens on 3.15.
- Do you have kallsyms enabled in your kernel (CONFIG_KALLSYMS=y)?
- Are there warnings issued by perf record, e.g. access to kernel symbols etc?
- perf report needs to know about your vmlinux image (the one that
contains the debug symbols etc in the root directory of the kernel
build). You can use '-k <file>' or '--vmlinux=<file>', cf. perf report
--help.
- You can dump the samples from perf.data using perf report -D. The
entries with 'PERF_RECORD_SAMPLE(IP, 2)' are for the user space apps.
- The '-v' option gives more info. This can be used multiple times ('-vv').
>
> Thanks.
>
> Sneha.
Regards,
Jean
>
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