Re: [PATCH] perf util: take pgoff into account when reporting elf to libdwfl
On Montag, 29. Oktober 2018 18:40:14 CET Arnaldo Carvalho de Melo wrote: > Em Mon, Oct 29, 2018 at 04:26:27PM +0100, Milian Wolff escreveu: > > On Monday, October 29, 2018 3:16:44 PM CET Milian Wolff wrote: > > > Libdwfl parses an ELF file itself and creates mappings for the > > > individual sections. Perf on the other hand sees raw mmap events which > > > represent individual sections. When we encounter an address pointing > > > into a mapping with pgoff != 0, we must take that into account and > > > report the file at the non-offset base address. > > > > > This fixes unwinding with libdwfl in some cases. E.g. for a file like: > > > > > > > Note that the backtrace is still stopping too early, when > > > compared to the nice results obtained via libunwind. It's > > > unclear so far what the reason for that is. > > > > The remaining issue is due to a bug in elfutils: > > > > https://sourceware.org/ml/elfutils-devel/2018-q4/msg00089.html > > > > With both patches applied, libunwind and elfutils produce the same output > > for the above scenario. > > I'm updating the patch to remove: > > "It's unclear so far what the reason for that is." > > Adding: > > "See https://sourceware.org/ml/elfutils-devel/2018-q4/msg00089.html for > a patch fixing that." > > Ok? Yes, thanks. I figured the fix for elfutils out after I submitted the perf patch. > Or are you saying that that "unclear" part applies to both libunwind > and elfutils? No, libunwind worked fine without these patches for this specific case. Cheers -- Milian Wolff | milian.wo...@kdab.com | Senior Software Engineer KDAB (Deutschland) GmbH, a KDAB Group company Tel: +49-30-521325470 KDAB - The Qt, C++ and OpenGL Experts smime.p7s Description: S/MIME cryptographic signature
Re: [PATCH] perf util: take pgoff into account when reporting elf to libdwfl
On Montag, 29. Oktober 2018 18:40:14 CET Arnaldo Carvalho de Melo wrote: > Em Mon, Oct 29, 2018 at 04:26:27PM +0100, Milian Wolff escreveu: > > On Monday, October 29, 2018 3:16:44 PM CET Milian Wolff wrote: > > > Libdwfl parses an ELF file itself and creates mappings for the > > > individual sections. Perf on the other hand sees raw mmap events which > > > represent individual sections. When we encounter an address pointing > > > into a mapping with pgoff != 0, we must take that into account and > > > report the file at the non-offset base address. > > > > > This fixes unwinding with libdwfl in some cases. E.g. for a file like: > > > > > > > Note that the backtrace is still stopping too early, when > > > compared to the nice results obtained via libunwind. It's > > > unclear so far what the reason for that is. > > > > The remaining issue is due to a bug in elfutils: > > > > https://sourceware.org/ml/elfutils-devel/2018-q4/msg00089.html > > > > With both patches applied, libunwind and elfutils produce the same output > > for the above scenario. > > I'm updating the patch to remove: > > "It's unclear so far what the reason for that is." > > Adding: > > "See https://sourceware.org/ml/elfutils-devel/2018-q4/msg00089.html for > a patch fixing that." > > Ok? Yes, thanks. I figured the fix for elfutils out after I submitted the perf patch. > Or are you saying that that "unclear" part applies to both libunwind > and elfutils? No, libunwind worked fine without these patches for this specific case. Cheers -- Milian Wolff | milian.wo...@kdab.com | Senior Software Engineer KDAB (Deutschland) GmbH, a KDAB Group company Tel: +49-30-521325470 KDAB - The Qt, C++ and OpenGL Experts smime.p7s Description: S/MIME cryptographic signature
Re: [PATCH] perf util: take pgoff into account when reporting elf to libdwfl
Em Mon, Oct 29, 2018 at 04:26:27PM +0100, Milian Wolff escreveu: > On Monday, October 29, 2018 3:16:44 PM CET Milian Wolff wrote: > > Libdwfl parses an ELF file itself and creates mappings for the > > individual sections. Perf on the other hand sees raw mmap events which > > represent individual sections. When we encounter an address pointing > > into a mapping with pgoff != 0, we must take that into account and > > report the file at the non-offset base address. > > > > This fixes unwinding with libdwfl in some cases. E.g. for a file like: > > > > > Note that the backtrace is still stopping too early, when > > compared to the nice results obtained via libunwind. It's > > unclear so far what the reason for that is. > > The remaining issue is due to a bug in elfutils: > > https://sourceware.org/ml/elfutils-devel/2018-q4/msg00089.html > > With both patches applied, libunwind and elfutils produce the same output for > the above scenario. I'm updating the patch to remove: "It's unclear so far what the reason for that is." Adding: "See https://sourceware.org/ml/elfutils-devel/2018-q4/msg00089.html for a patch fixing that." Ok? Or are you saying that that "unclear" part applies to both libunwind and elfutils? - Arnaldo
Re: [PATCH] perf util: take pgoff into account when reporting elf to libdwfl
Em Mon, Oct 29, 2018 at 04:26:27PM +0100, Milian Wolff escreveu: > On Monday, October 29, 2018 3:16:44 PM CET Milian Wolff wrote: > > Libdwfl parses an ELF file itself and creates mappings for the > > individual sections. Perf on the other hand sees raw mmap events which > > represent individual sections. When we encounter an address pointing > > into a mapping with pgoff != 0, we must take that into account and > > report the file at the non-offset base address. > > > > This fixes unwinding with libdwfl in some cases. E.g. for a file like: > > > > > Note that the backtrace is still stopping too early, when > > compared to the nice results obtained via libunwind. It's > > unclear so far what the reason for that is. > > The remaining issue is due to a bug in elfutils: > > https://sourceware.org/ml/elfutils-devel/2018-q4/msg00089.html > > With both patches applied, libunwind and elfutils produce the same output for > the above scenario. I'm updating the patch to remove: "It's unclear so far what the reason for that is." Adding: "See https://sourceware.org/ml/elfutils-devel/2018-q4/msg00089.html for a patch fixing that." Ok? Or are you saying that that "unclear" part applies to both libunwind and elfutils? - Arnaldo
Re: [PATCH] perf util: take pgoff into account when reporting elf to libdwfl
On Monday, October 29, 2018 3:16:44 PM CET Milian Wolff wrote: > Libdwfl parses an ELF file itself and creates mappings for the > individual sections. Perf on the other hand sees raw mmap events which > represent individual sections. When we encounter an address pointing > into a mapping with pgoff != 0, we must take that into account and > report the file at the non-offset base address. > > This fixes unwinding with libdwfl in some cases. E.g. for a file like: > Note that the backtrace is still stopping too early, when > compared to the nice results obtained via libunwind. It's > unclear so far what the reason for that is. The remaining issue is due to a bug in elfutils: https://sourceware.org/ml/elfutils-devel/2018-q4/msg00089.html With both patches applied, libunwind and elfutils produce the same output for the above scenario. Cheers -- Milian Wolff | milian.wo...@kdab.com | Senior Software Engineer KDAB (Deutschland) GmbH, a KDAB Group company Tel: +49-30-521325470 KDAB - The Qt, C++ and OpenGL Experts smime.p7s Description: S/MIME cryptographic signature
Re: [PATCH] perf util: take pgoff into account when reporting elf to libdwfl
On Monday, October 29, 2018 3:16:44 PM CET Milian Wolff wrote: > Libdwfl parses an ELF file itself and creates mappings for the > individual sections. Perf on the other hand sees raw mmap events which > represent individual sections. When we encounter an address pointing > into a mapping with pgoff != 0, we must take that into account and > report the file at the non-offset base address. > > This fixes unwinding with libdwfl in some cases. E.g. for a file like: > Note that the backtrace is still stopping too early, when > compared to the nice results obtained via libunwind. It's > unclear so far what the reason for that is. The remaining issue is due to a bug in elfutils: https://sourceware.org/ml/elfutils-devel/2018-q4/msg00089.html With both patches applied, libunwind and elfutils produce the same output for the above scenario. Cheers -- Milian Wolff | milian.wo...@kdab.com | Senior Software Engineer KDAB (Deutschland) GmbH, a KDAB Group company Tel: +49-30-521325470 KDAB - The Qt, C++ and OpenGL Experts smime.p7s Description: S/MIME cryptographic signature
Re: [PATCH] perf util: take pgoff into account when reporting elf to libdwfl
On Mon, Oct 29, 2018 at 03:16:44PM +0100, Milian Wolff wrote:
> Libdwfl parses an ELF file itself and creates mappings for the
> individual sections. Perf on the other hand sees raw mmap events which
> represent individual sections. When we encounter an address pointing
> into a mapping with pgoff != 0, we must take that into account and
> report the file at the non-offset base address.
>
> This fixes unwinding with libdwfl in some cases. E.g. for a file like:
>
> ```
> #include
> #include
> #include
> #include
> #include
> #include
> #include
> #include
>
> using namespace std;
>
> mutex g_mutex;
>
> double worker()
> {
> lock_guard guard(g_mutex);
> uniform_real_distribution uniform(-1E5, 1E5);
> default_random_engine engine;
> double s = 0;
> for (int i = 0; i < 1000; ++i) {
> s += norm(complex(uniform(engine), uniform(engine)));
> }
> cout << s << endl;
> return s;
> }
>
> int main()
> {
> vector> results;
> for (int i = 0; i < 1; ++i) {
> results.push_back(async(launch::async, worker));
> }
> return 0;
> }
> ```
>
> Compile it with `g++ -g -O2`, then record it with
> `perf record --call-graph dwarf -e sched:sched_switch`.
>
> When you analyze it with `perf script` and libunwind, you should see:
>
> ```
> cpp-locking 20038 [005] 54830.236589: sched:sched_switch:
> prev_comm=cpp-locking prev_pid=20038 prev_prio=120 prev_state=T ==>
> next_comm=swapper/5 next_pid=0 next_prio=120
> b166fec5 __sched_text_start+0x545
> (/lib/modules/4.14.78-1-lts/build/vmlinux)
> b166fec5 __sched_text_start+0x545
> (/lib/modules/4.14.78-1-lts/build/vmlinux)
> b1670208 schedule+0x28
> (/lib/modules/4.14.78-1-lts/build/vmlinux)
> b16737cc rwsem_down_read_failed+0xec
> (/lib/modules/4.14.78-1-lts/build/vmlinux)
> b1665e04 call_rwsem_down_read_failed+0x14
> (/lib/modules/4.14.78-1-lts/build/vmlinux)
> b1672a03 down_read+0x13
> (/lib/modules/4.14.78-1-lts/build/vmlinux)
> b106bd85 __do_page_fault+0x445
> (/lib/modules/4.14.78-1-lts/build/vmlinux)
> b18015f5 page_fault+0x45
> (/lib/modules/4.14.78-1-lts/build/vmlinux)
> 7f38e4252591 new_heap+0x101 (/usr/lib/libc-2.28.so)
> 7f38e4252d0b arena_get2.part.4+0x2fb (/usr/lib/libc-2.28.so)
> 7f38e4255b1c tcache_init.part.6+0xec (/usr/lib/libc-2.28.so)
> 7f38e42569e5 __GI___libc_malloc+0x115 (inlined)
> 7f38e4241790 __GI__IO_file_doallocate+0x90 (inlined)
> 7f38e424fbbf __GI__IO_doallocbuf+0x4f (inlined)
> 7f38e424ee47 __GI__IO_file_overflow+0x197 (inlined)
> 7f38e424df36 _IO_new_file_xsputn+0x116 (inlined)
> 7f38e4242bfb __GI__IO_fwrite+0xdb (inlined)
> 7f38e463fa6d std::basic_streambuf
> >::sputn(char const*, long)+0x1cd (inlined)
> 7f38e463fa6d std::ostreambuf_iterator std::char_traits >::_M_put(char const*, long)+0x1cd (inlined)
> 7f38e463fa6d std::ostreambuf_iterator std::char_traits > std::__write(std::ostreambuf_iterator std::char_traits >, char const*, int)+0x1cd (inlined)
> 7f38e463fa6d std::ostreambuf_iterator std::char_traits > std::num_put std::char_traits >
> >::_M_insert_float(std::ostreambuf_iterator
> 7f38e464bd70 std::num_put std::char_traits > >::put(std::ostreambuf_iterator std::char_traits >, std::ios_base&, char, double) const+0x90 (inl>
> 7f38e464bd70 std::ostream&
> std::ostream::_M_insert(double)+0x90 (/usr/lib/libstdc++.so.6.0.25)
> 563b9cb502f7 std::ostream::operator<<(double)+0xb7 (inlined)
> 563b9cb502f7 worker()+0xb7
> (/ssd/milian/projects/kdab/rnd/hotspot/build/tests/test-clients/cpp-locking/cpp-locking)
> 563b9cb506fb double std::__invoke_impl (*)()>(std::__invoke_other, double (*&&)())+0x2b (inlined)
> 563b9cb506fb std::__invoke_result::type
> std::__invoke(double (*&&)())+0x2b (inlined)
> 563b9cb506fb decltype (__invoke((_S_declval<0ul>)()))
> std::thread::_Invoker
> >::_M_invoke<0ul>(std::_Index_tuple<0ul>)+0x2b (inlined)
> 563b9cb506fb std::thread::_Invoker
> >::operator()()+0x2b (inlined)
> 563b9cb506fb
> std::__future_base::_Task_setter,
> std::__future_base::_Result_base::_Deleter>,
> std::thread::_Invoker >, dou>
> 563b9cb506fb
> std::_Function_handler std::__future_base::_Result_base::_Deleter> (),
> std::__future_base::_Task_setter
> 563b9cb507e8
> std::function std::__future_base::_Result_base::_Deleter> ()>::operator()() const+0x28
> (inlined)
> 563b9cb507e8
> std::__future_base::_State_baseV2::_M_do_set(std::function std::__future_base::_Result_base::_Deleter> ()>*, bool*)+0x28 (/ssd/milian/>
> 7f38e46d24fe __pthread_once_slow+0xbe
> (/usr/lib/libpthread-2.28.so)
> 563b9cb51149
Re: [PATCH] perf util: take pgoff into account when reporting elf to libdwfl
On Mon, Oct 29, 2018 at 03:16:44PM +0100, Milian Wolff wrote:
> Libdwfl parses an ELF file itself and creates mappings for the
> individual sections. Perf on the other hand sees raw mmap events which
> represent individual sections. When we encounter an address pointing
> into a mapping with pgoff != 0, we must take that into account and
> report the file at the non-offset base address.
>
> This fixes unwinding with libdwfl in some cases. E.g. for a file like:
>
> ```
> #include
> #include
> #include
> #include
> #include
> #include
> #include
> #include
>
> using namespace std;
>
> mutex g_mutex;
>
> double worker()
> {
> lock_guard guard(g_mutex);
> uniform_real_distribution uniform(-1E5, 1E5);
> default_random_engine engine;
> double s = 0;
> for (int i = 0; i < 1000; ++i) {
> s += norm(complex(uniform(engine), uniform(engine)));
> }
> cout << s << endl;
> return s;
> }
>
> int main()
> {
> vector> results;
> for (int i = 0; i < 1; ++i) {
> results.push_back(async(launch::async, worker));
> }
> return 0;
> }
> ```
>
> Compile it with `g++ -g -O2`, then record it with
> `perf record --call-graph dwarf -e sched:sched_switch`.
>
> When you analyze it with `perf script` and libunwind, you should see:
>
> ```
> cpp-locking 20038 [005] 54830.236589: sched:sched_switch:
> prev_comm=cpp-locking prev_pid=20038 prev_prio=120 prev_state=T ==>
> next_comm=swapper/5 next_pid=0 next_prio=120
> b166fec5 __sched_text_start+0x545
> (/lib/modules/4.14.78-1-lts/build/vmlinux)
> b166fec5 __sched_text_start+0x545
> (/lib/modules/4.14.78-1-lts/build/vmlinux)
> b1670208 schedule+0x28
> (/lib/modules/4.14.78-1-lts/build/vmlinux)
> b16737cc rwsem_down_read_failed+0xec
> (/lib/modules/4.14.78-1-lts/build/vmlinux)
> b1665e04 call_rwsem_down_read_failed+0x14
> (/lib/modules/4.14.78-1-lts/build/vmlinux)
> b1672a03 down_read+0x13
> (/lib/modules/4.14.78-1-lts/build/vmlinux)
> b106bd85 __do_page_fault+0x445
> (/lib/modules/4.14.78-1-lts/build/vmlinux)
> b18015f5 page_fault+0x45
> (/lib/modules/4.14.78-1-lts/build/vmlinux)
> 7f38e4252591 new_heap+0x101 (/usr/lib/libc-2.28.so)
> 7f38e4252d0b arena_get2.part.4+0x2fb (/usr/lib/libc-2.28.so)
> 7f38e4255b1c tcache_init.part.6+0xec (/usr/lib/libc-2.28.so)
> 7f38e42569e5 __GI___libc_malloc+0x115 (inlined)
> 7f38e4241790 __GI__IO_file_doallocate+0x90 (inlined)
> 7f38e424fbbf __GI__IO_doallocbuf+0x4f (inlined)
> 7f38e424ee47 __GI__IO_file_overflow+0x197 (inlined)
> 7f38e424df36 _IO_new_file_xsputn+0x116 (inlined)
> 7f38e4242bfb __GI__IO_fwrite+0xdb (inlined)
> 7f38e463fa6d std::basic_streambuf
> >::sputn(char const*, long)+0x1cd (inlined)
> 7f38e463fa6d std::ostreambuf_iterator std::char_traits >::_M_put(char const*, long)+0x1cd (inlined)
> 7f38e463fa6d std::ostreambuf_iterator std::char_traits > std::__write(std::ostreambuf_iterator std::char_traits >, char const*, int)+0x1cd (inlined)
> 7f38e463fa6d std::ostreambuf_iterator std::char_traits > std::num_put std::char_traits >
> >::_M_insert_float(std::ostreambuf_iterator
> 7f38e464bd70 std::num_put std::char_traits > >::put(std::ostreambuf_iterator std::char_traits >, std::ios_base&, char, double) const+0x90 (inl>
> 7f38e464bd70 std::ostream&
> std::ostream::_M_insert(double)+0x90 (/usr/lib/libstdc++.so.6.0.25)
> 563b9cb502f7 std::ostream::operator<<(double)+0xb7 (inlined)
> 563b9cb502f7 worker()+0xb7
> (/ssd/milian/projects/kdab/rnd/hotspot/build/tests/test-clients/cpp-locking/cpp-locking)
> 563b9cb506fb double std::__invoke_impl (*)()>(std::__invoke_other, double (*&&)())+0x2b (inlined)
> 563b9cb506fb std::__invoke_result::type
> std::__invoke(double (*&&)())+0x2b (inlined)
> 563b9cb506fb decltype (__invoke((_S_declval<0ul>)()))
> std::thread::_Invoker
> >::_M_invoke<0ul>(std::_Index_tuple<0ul>)+0x2b (inlined)
> 563b9cb506fb std::thread::_Invoker
> >::operator()()+0x2b (inlined)
> 563b9cb506fb
> std::__future_base::_Task_setter,
> std::__future_base::_Result_base::_Deleter>,
> std::thread::_Invoker >, dou>
> 563b9cb506fb
> std::_Function_handler std::__future_base::_Result_base::_Deleter> (),
> std::__future_base::_Task_setter
> 563b9cb507e8
> std::function std::__future_base::_Result_base::_Deleter> ()>::operator()() const+0x28
> (inlined)
> 563b9cb507e8
> std::__future_base::_State_baseV2::_M_do_set(std::function std::__future_base::_Result_base::_Deleter> ()>*, bool*)+0x28 (/ssd/milian/>
> 7f38e46d24fe __pthread_once_slow+0xbe
> (/usr/lib/libpthread-2.28.so)
> 563b9cb51149
[PATCH] perf util: take pgoff into account when reporting elf to libdwfl
Libdwfl parses an ELF file itself and creates mappings for the
individual sections. Perf on the other hand sees raw mmap events which
represent individual sections. When we encounter an address pointing
into a mapping with pgoff != 0, we must take that into account and
report the file at the non-offset base address.
This fixes unwinding with libdwfl in some cases. E.g. for a file like:
```
#include
#include
#include
#include
#include
#include
#include
#include
using namespace std;
mutex g_mutex;
double worker()
{
lock_guard guard(g_mutex);
uniform_real_distribution uniform(-1E5, 1E5);
default_random_engine engine;
double s = 0;
for (int i = 0; i < 1000; ++i) {
s += norm(complex(uniform(engine), uniform(engine)));
}
cout << s << endl;
return s;
}
int main()
{
vector> results;
for (int i = 0; i < 1; ++i) {
results.push_back(async(launch::async, worker));
}
return 0;
}
```
Compile it with `g++ -g -O2`, then record it with
`perf record --call-graph dwarf -e sched:sched_switch`.
When you analyze it with `perf script` and libunwind, you should see:
```
cpp-locking 20038 [005] 54830.236589: sched:sched_switch: prev_comm=cpp-locking
prev_pid=20038 prev_prio=120 prev_state=T ==> next_comm=swapper/5 next_pid=0
next_prio=120
b166fec5 __sched_text_start+0x545
(/lib/modules/4.14.78-1-lts/build/vmlinux)
b166fec5 __sched_text_start+0x545
(/lib/modules/4.14.78-1-lts/build/vmlinux)
b1670208 schedule+0x28
(/lib/modules/4.14.78-1-lts/build/vmlinux)
b16737cc rwsem_down_read_failed+0xec
(/lib/modules/4.14.78-1-lts/build/vmlinux)
b1665e04 call_rwsem_down_read_failed+0x14
(/lib/modules/4.14.78-1-lts/build/vmlinux)
b1672a03 down_read+0x13
(/lib/modules/4.14.78-1-lts/build/vmlinux)
b106bd85 __do_page_fault+0x445
(/lib/modules/4.14.78-1-lts/build/vmlinux)
b18015f5 page_fault+0x45
(/lib/modules/4.14.78-1-lts/build/vmlinux)
7f38e4252591 new_heap+0x101 (/usr/lib/libc-2.28.so)
7f38e4252d0b arena_get2.part.4+0x2fb (/usr/lib/libc-2.28.so)
7f38e4255b1c tcache_init.part.6+0xec (/usr/lib/libc-2.28.so)
7f38e42569e5 __GI___libc_malloc+0x115 (inlined)
7f38e4241790 __GI__IO_file_doallocate+0x90 (inlined)
7f38e424fbbf __GI__IO_doallocbuf+0x4f (inlined)
7f38e424ee47 __GI__IO_file_overflow+0x197 (inlined)
7f38e424df36 _IO_new_file_xsputn+0x116 (inlined)
7f38e4242bfb __GI__IO_fwrite+0xdb (inlined)
7f38e463fa6d std::basic_streambuf
>::sputn(char const*, long)+0x1cd (inlined)
7f38e463fa6d std::ostreambuf_iterator
>::_M_put(char const*, long)+0x1cd (inlined)
7f38e463fa6d std::ostreambuf_iterator
> std::__write(std::ostreambuf_iterator >,
char const*, int)+0x1cd (inlined)
7f38e463fa6d std::ostreambuf_iterator
> std::num_put >
>::_M_insert_float(std::ostreambuf_iterator
7f38e464bd70 std::num_put > >::put(std::ostreambuf_iterator >, std::ios_base&, char, double) const+0x90 (inl>
7f38e464bd70 std::ostream&
std::ostream::_M_insert(double)+0x90 (/usr/lib/libstdc++.so.6.0.25)
563b9cb502f7 std::ostream::operator<<(double)+0xb7 (inlined)
563b9cb502f7 worker()+0xb7
(/ssd/milian/projects/kdab/rnd/hotspot/build/tests/test-clients/cpp-locking/cpp-locking)
563b9cb506fb double std::__invoke_impl(std::__invoke_other, double (*&&)())+0x2b (inlined)
563b9cb506fb std::__invoke_result::type
std::__invoke(double (*&&)())+0x2b (inlined)
563b9cb506fb decltype (__invoke((_S_declval<0ul>)()))
std::thread::_Invoker
>::_M_invoke<0ul>(std::_Index_tuple<0ul>)+0x2b (inlined)
563b9cb506fb std::thread::_Invoker
>::operator()()+0x2b (inlined)
563b9cb506fb
std::__future_base::_Task_setter,
std::__future_base::_Result_base::_Deleter>,
std::thread::_Invoker >, dou>
563b9cb506fb
std::_Function_handler (),
std::__future_base::_Task_setter
563b9cb507e8
std::function ()>::operator()() const+0x28
(inlined)
563b9cb507e8
std::__future_base::_State_baseV2::_M_do_set(std::function ()>*, bool*)+0x28 (/ssd/milian/>
7f38e46d24fe __pthread_once_slow+0xbe (/usr/lib/libpthread-2.28.so)
563b9cb51149 __gthread_once+0xe9 (inlined)
563b9cb51149 void std::call_once ()>*, bool*)>
563b9cb51149
std::__future_base::_State_baseV2::_M_set_result(std::function ()>, bool)+0xe9 (inlined)
563b9cb51149
std::__future_base::_Async_state_impl >, double>::_Async_state_impl(std::thread::_Invoker >&&)::{lambda()#1}::op>
563b9cb51149 void std::__invoke_impl >, double>::_Async_state_impl(std::thread::_Invoker
563b9cb51149
std::__invoke_result >, double>::_Async_state_impl(std::thread::_Invoker >>
[PATCH] perf util: take pgoff into account when reporting elf to libdwfl
Libdwfl parses an ELF file itself and creates mappings for the
individual sections. Perf on the other hand sees raw mmap events which
represent individual sections. When we encounter an address pointing
into a mapping with pgoff != 0, we must take that into account and
report the file at the non-offset base address.
This fixes unwinding with libdwfl in some cases. E.g. for a file like:
```
#include
#include
#include
#include
#include
#include
#include
#include
using namespace std;
mutex g_mutex;
double worker()
{
lock_guard guard(g_mutex);
uniform_real_distribution uniform(-1E5, 1E5);
default_random_engine engine;
double s = 0;
for (int i = 0; i < 1000; ++i) {
s += norm(complex(uniform(engine), uniform(engine)));
}
cout << s << endl;
return s;
}
int main()
{
vector> results;
for (int i = 0; i < 1; ++i) {
results.push_back(async(launch::async, worker));
}
return 0;
}
```
Compile it with `g++ -g -O2`, then record it with
`perf record --call-graph dwarf -e sched:sched_switch`.
When you analyze it with `perf script` and libunwind, you should see:
```
cpp-locking 20038 [005] 54830.236589: sched:sched_switch: prev_comm=cpp-locking
prev_pid=20038 prev_prio=120 prev_state=T ==> next_comm=swapper/5 next_pid=0
next_prio=120
b166fec5 __sched_text_start+0x545
(/lib/modules/4.14.78-1-lts/build/vmlinux)
b166fec5 __sched_text_start+0x545
(/lib/modules/4.14.78-1-lts/build/vmlinux)
b1670208 schedule+0x28
(/lib/modules/4.14.78-1-lts/build/vmlinux)
b16737cc rwsem_down_read_failed+0xec
(/lib/modules/4.14.78-1-lts/build/vmlinux)
b1665e04 call_rwsem_down_read_failed+0x14
(/lib/modules/4.14.78-1-lts/build/vmlinux)
b1672a03 down_read+0x13
(/lib/modules/4.14.78-1-lts/build/vmlinux)
b106bd85 __do_page_fault+0x445
(/lib/modules/4.14.78-1-lts/build/vmlinux)
b18015f5 page_fault+0x45
(/lib/modules/4.14.78-1-lts/build/vmlinux)
7f38e4252591 new_heap+0x101 (/usr/lib/libc-2.28.so)
7f38e4252d0b arena_get2.part.4+0x2fb (/usr/lib/libc-2.28.so)
7f38e4255b1c tcache_init.part.6+0xec (/usr/lib/libc-2.28.so)
7f38e42569e5 __GI___libc_malloc+0x115 (inlined)
7f38e4241790 __GI__IO_file_doallocate+0x90 (inlined)
7f38e424fbbf __GI__IO_doallocbuf+0x4f (inlined)
7f38e424ee47 __GI__IO_file_overflow+0x197 (inlined)
7f38e424df36 _IO_new_file_xsputn+0x116 (inlined)
7f38e4242bfb __GI__IO_fwrite+0xdb (inlined)
7f38e463fa6d std::basic_streambuf
>::sputn(char const*, long)+0x1cd (inlined)
7f38e463fa6d std::ostreambuf_iterator
>::_M_put(char const*, long)+0x1cd (inlined)
7f38e463fa6d std::ostreambuf_iterator
> std::__write(std::ostreambuf_iterator >,
char const*, int)+0x1cd (inlined)
7f38e463fa6d std::ostreambuf_iterator
> std::num_put >
>::_M_insert_float(std::ostreambuf_iterator
7f38e464bd70 std::num_put > >::put(std::ostreambuf_iterator >, std::ios_base&, char, double) const+0x90 (inl>
7f38e464bd70 std::ostream&
std::ostream::_M_insert(double)+0x90 (/usr/lib/libstdc++.so.6.0.25)
563b9cb502f7 std::ostream::operator<<(double)+0xb7 (inlined)
563b9cb502f7 worker()+0xb7
(/ssd/milian/projects/kdab/rnd/hotspot/build/tests/test-clients/cpp-locking/cpp-locking)
563b9cb506fb double std::__invoke_impl(std::__invoke_other, double (*&&)())+0x2b (inlined)
563b9cb506fb std::__invoke_result::type
std::__invoke(double (*&&)())+0x2b (inlined)
563b9cb506fb decltype (__invoke((_S_declval<0ul>)()))
std::thread::_Invoker
>::_M_invoke<0ul>(std::_Index_tuple<0ul>)+0x2b (inlined)
563b9cb506fb std::thread::_Invoker
>::operator()()+0x2b (inlined)
563b9cb506fb
std::__future_base::_Task_setter,
std::__future_base::_Result_base::_Deleter>,
std::thread::_Invoker >, dou>
563b9cb506fb
std::_Function_handler (),
std::__future_base::_Task_setter
563b9cb507e8
std::function ()>::operator()() const+0x28
(inlined)
563b9cb507e8
std::__future_base::_State_baseV2::_M_do_set(std::function ()>*, bool*)+0x28 (/ssd/milian/>
7f38e46d24fe __pthread_once_slow+0xbe (/usr/lib/libpthread-2.28.so)
563b9cb51149 __gthread_once+0xe9 (inlined)
563b9cb51149 void std::call_once ()>*, bool*)>
563b9cb51149
std::__future_base::_State_baseV2::_M_set_result(std::function ()>, bool)+0xe9 (inlined)
563b9cb51149
std::__future_base::_Async_state_impl >, double>::_Async_state_impl(std::thread::_Invoker >&&)::{lambda()#1}::op>
563b9cb51149 void std::__invoke_impl >, double>::_Async_state_impl(std::thread::_Invoker
563b9cb51149
std::__invoke_result >, double>::_Async_state_impl(std::thread::_Invoker >>
