Symbols not decoded in 0.0.2.PERF

Symbols not decoded in 0.0.2.PERF

[Johan Tibell]

Hi,

I'm trying to use perf record/report on a non-stripped, Haskell binary
(i.e. compiled using GHC). Unfortunately, not all symbols are
decoded*:

    75.28%            bench  ./bench                    [.] 0x000000002b612b
     7.11%            bench  /lib/libc-2.11.1.so        [.] memcpy
     5.47%            bench  ./bench                    [.] 0x0000000000438f
     3.47%            bench  ./bench                    [.] allocate
     1.86%            bench  ./bench                    [.] s1Ol_info
     1.65%            bench  ./bench                    [.] s1Ok_info
     0.62%            bench  ./bench                    [.] memcpy@plt
     0.48%            bench  ./bench                    [.] clearNurseries
     0.33%            bench  ./bench                    [.] evacuate1
     0.24%            bench  ./bench                    [.] GarbageCollect

How can I figure out what 0x000000002b612b corresponds to?

perf version: 0.0.2.PERF (installed from Ubuntu package)
Kernel version: 2.6.32

$ cat /proc/cpuinfo
processor	: 0
vendor_id	: GenuineIntel
cpu family	: 6
model		: 44
model name	: Intel(R) Xeon(R) CPU           X5650  @ 2.67GHz

* It could be the case that GHC is generating symbols that perf cannot
interpret somehow. If we can confirm this is the case we can try to
fix that.

-- Johan

Re: Symbols not decoded in 0.0.2.PERF

[Johan Tibell]

On Tue, Apr 19, 2011 at 1:22 PM, Johan Tibell <johan.tibell@gmail.com> wrote:
> * It could be the case that GHC is generating symbols that perf cannot
> interpret somehow. If we can confirm this is the case we can try to
> fix that.

I spent the day making sure this is not the case. All the Haskell
functions now have the correct (fingers crossed) .type and .size ELF
directives:

    74.18%            bench  ./bench               [.] 0x000000002ac524
     7.19%            bench  /lib/libc-2.11.1.so   [.] memcpy
     4.53%            bench  ./bench               [.] s1Ok_info
     4.28%            bench  ./bench               [.] s1Ol_info
     3.28%            bench  ./bench               [.] allocate
     0.74%            bench  ./bench               [.] Main_zdwa_info
     0.62%            bench  ./bench               [.] memcpy@plt
     0.45%            bench  ./bench               [.] clearNurseries
     0.36%            bench  ./bench               [.] evacuate
     0.27%            bench  ./bench               [.] stg_newArrayzh

Entries 3-6 and 8-10 are Haskell functions. The top entry is still unknown.

If it matters, the little program I'm running stresses array copying
and I would expect it to spend most of its time in memcpy, but these
numbers suggests that it isn't. Could it be some stripped C libraries
or some code generated by gcc specially for memcpy that's accounting
for the top entry?

Johan

Re: Symbols not decoded in 0.0.2.PERF

[Johan Tibell]

On Tue, Apr 19, 2011 at 5:58 PM, Johan Tibell <johan.tibell@gmail.com> wrote:
> On Tue, Apr 19, 2011 at 1:22 PM, Johan Tibell <johan.tibell@gmail.com> wrote:
>> * It could be the case that GHC is generating symbols that perf cannot
>> interpret somehow. If we can confirm this is the case we can try to
>> fix that.
>
> I spent the day making sure this is not the case. All the Haskell
> functions now have the correct (fingers crossed) .type and .size ELF
> directives:

Problem solved. There were indeed some functions that didn't have any
.size directives, making perf (or is that objdump?) fail to recognize
the symbols.

Sorry for the noise.

Johan