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Improved sampling performance #74

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merged 4 commits into from
Jul 12, 2022
Merged

Improved sampling performance #74

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4cf9d06
Improved sampling performance
jrmadsen Jun 29, 2022
10fa5e4
Sampling tweaks
jrmadsen Jun 29, 2022
cb07574
Fix empty HW counter desc + category for sampling
jrmadsen Jul 12, 2022
c6950aa
Limit the SIGALRM frequency
jrmadsen Jul 12, 2022
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154 changes: 72 additions & 82 deletions source/lib/omnitrace/library/components/backtrace.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -29,6 +29,7 @@
#include "library/perfetto.hpp"
#include "library/ptl.hpp"
#include "library/sampling.hpp"
#include "library/tracing.hpp"

#include <timemory/backends/papi.hpp>
#include <timemory/backends/threading.hpp>
Expand Down Expand Up @@ -64,11 +65,17 @@
#include <regex>
#include <sstream>
#include <string>
#include <string_view>
#include <type_traits>

#include <pthread.h>
#include <signal.h>

namespace tracing
{
using namespace ::omnitrace::tracing;
}

namespace
{
template <typename... Tp>
Expand Down Expand Up @@ -145,13 +152,20 @@ backtrace::operator<(const backtrace& rhs) const
return (m_ts == rhs.m_ts) ? (m_tid < rhs.m_tid) : (m_ts < rhs.m_ts);
}

std::vector<std::string>
std::vector<std::string_view>
backtrace::get() const
{
std::vector<std::string> _v{};
_v.reserve(m_size);
for(size_t i = 0; i < m_size; ++i)
_v.emplace_back(m_data.at(i));
std::vector<std::string_view> _v = {};
if(m_size == 0) return _v;
size_t _size = 0;
for(const auto* itr : m_data)
_size += (strlen(itr) > 0) ? 1 : 0;
_v.reserve(_size);
for(const auto* itr : m_data)
{
if(strlen(itr) > 0) _v.emplace_back(itr);
}
std::reverse(_v.begin(), _v.end());
return _v;
}

Expand Down Expand Up @@ -281,28 +295,8 @@ backtrace::sample(int signum)
m_ctx_swch = _cache.get_num_priority_context_switch() +
_cache.get_num_voluntary_context_switch();
m_page_flt = _cache.get_num_major_page_faults() + _cache.get_num_minor_page_faults();
m_data = tim::get_unw_backtrace<stack_depth, 4, false>();
auto* itr = m_data.begin();
for(; itr != m_data.end(); ++itr, ++m_size)
{
if(strlen(*itr) == 0) break;
}
std::reverse(m_data.begin(), itr);
if(!get_debug_sampling())
{
bool _ignore = false;
for(auto& itr : m_data)
{
if(strlen(itr) == 0) break;
if(strncmp(itr, "funlockfile", 11) == 0) _ignore = true;
if(_ignore && strlen(itr) > 0)
{
OMNITRACE_DEBUG("Discarding sample: '%s'...\n", itr);
itr[0] = '\0';
--m_size;
}
}
}
m_data = tim::get_unw_backtrace<stack_depth, 2, false>();
m_size = m_data.size();

if constexpr(tim::trait::is_available<hw_counters>::value)
{
Expand Down Expand Up @@ -337,7 +331,7 @@ backtrace::configure(bool _setup, int64_t _tid)
if(get_papi_vector(_tid)) get_papi_vector(_tid)->start();
}

auto _alrm_freq = 1.0 / std::min<double>(get_sampling_freq(), 5.0);
auto _alrm_freq = 1.0 / std::min<double>(get_sampling_freq(), 20.0);
auto _prof_freq = 1.0 / get_sampling_freq();
auto _delay = std::max<double>(1.0e-3, get_sampling_delay());

Expand All @@ -348,8 +342,10 @@ backtrace::configure(bool _setup, int64_t _tid)
_sampler->set_flags(SA_RESTART);
_sampler->set_delay(_delay);
_sampler->set_verbose(std::min<size_t>(_sampler->get_verbose(), 2));
_sampler->set_frequency(_prof_freq, { SIGPROF });
_sampler->set_frequency(_alrm_freq, { SIGALRM });
if(_signal_types->count(SIGALRM) > 0)
_sampler->set_frequency(_alrm_freq, { SIGALRM });
if(_signal_types->count(SIGPROF) > 0)
_sampler->set_frequency(_prof_freq, { SIGPROF });

static_assert(tim::trait::buffer_size<sampling::sampler_t>::value > 0,
"Error! Zero buffer size");
Expand Down Expand Up @@ -437,42 +433,33 @@ backtrace::post_process(int64_t _tid)
_init->m_ts, pthread_create_gotcha::get_execution_time(_tid)->first);

// check whether the call-stack entry should be used. -1 means break, 0 means continue
auto _use_label = [](const std::string& _lbl, bool _check_internal) -> short {
auto _use_label = [](std::string_view _lbl) -> short {
// debugging feature
static bool _keep_internal =
tim::get_env<bool>("OMNITRACE_SAMPLING_KEEP_INTERNAL", get_debug_sampling());
const auto _npos = std::string::npos;
if(_keep_internal) return 1;
if(_lbl.find("omnitrace_init_tooling") != _npos) return -1;
if(_lbl.find("omnitrace_push_trace") != _npos) return -1;
if(_lbl.find("omnitrace_pop_trace") != _npos) return -1;
if(_lbl.find("amd_comgr_") == 0) return -1;
if(_check_internal)
{
if(std::regex_search(
_lbl, std::regex("(14pthread_gotcha7wrapper|default_error_condition)",
std::regex_constants::optimize)))
return 0;
else if(std::regex_search(
_lbl, std::regex("(8sampling9backtrace9configure|"
"8sampling15unblock_signals|pthread_sigmask)",
std::regex_constants::optimize)))
return 0;
}
if(_lbl.find("omnitrace::common::") != _npos) return -1;
if(_lbl.find("omnitrace_") != _npos) return -1;
if(_lbl.find("roctracer_") != _npos) return -1;
if(_lbl.find("perfetto::") != _npos) return -1;
if(_lbl.find("omnitrace::") != _npos) return 0;
if(_lbl.find("tim::") != _npos) return 0;
if(_lbl == "funlockfile") return 0;
return 1;
};

// in the dyninst binary rewrite runtime, instrumented functions are appended with
// "_dyninst", i.e. "main" will show up as "main_dyninst" in the backtrace.
auto _patch_label = [](std::string _lbl) -> std::string {
auto _patch_label = [](std::string_view _lbl) -> std::string {
// debugging feature
static bool _keep_suffix = tim::get_env<bool>(
"OMNITRACE_SAMPLING_KEEP_DYNINST_SUFFIX", get_debug_sampling());
if(_keep_suffix) return _lbl;
if(_keep_suffix) return std::string{ _lbl };
const std::string _dyninst{ "_dyninst" };
auto _pos = _lbl.find(_dyninst);
if(_pos == std::string::npos) return _lbl;
return _lbl.replace(_pos, _dyninst.length(), "");
if(_pos == std::string::npos) return std::string{ _lbl };
return std::string{ _lbl }.replace(_pos, _dyninst.length(), "");
};

using common_type_t = typename hw_counters::common_type;
Expand All @@ -497,9 +484,12 @@ backtrace::post_process(int64_t _tid)
{
for(auto& itr : _hw_cnt_labels)
{
std::string _desc = tim::papi::get_event_info(itr).short_descr;
if(_desc.empty()) _desc = itr;
OMNITRACE_CI_THROW(_desc.empty(), "Empty description for %s\n",
itr.c_str());
perfetto_counter_track<hw_counters>::emplace(
_tid, JOIN(' ', "Thread", tim::papi::get_event_info(itr).short_descr,
_tid_name, "(S)"));
_tid, JOIN(' ', "Thread", _desc, _tid_name, "(S)"));
}
}

Expand Down Expand Up @@ -579,35 +569,43 @@ backtrace::post_process(int64_t _tid)
bool _rename) {
if(_rename)
threading::set_thread_name(TIMEMORY_JOIN(" ", "Thread", _tid, "(S)").c_str());
auto _last_wall_ts = _init->get_timestamp();

uint64_t _beg_ns = pthread_create_gotcha::get_execution_time(_tid)->first;
uint64_t _end_ns = pthread_create_gotcha::get_execution_time(_tid)->second;
uint64_t _last_wall_ts = _init->get_timestamp();

tracing::push_perfetto_ts(category::sampling{}, "samples [omnitrace]", _beg_ns,
"begin_ns", _beg_ns);

for(const auto& ditr : _data)
{
const auto* _bt = ditr->get<backtrace>();
if(_bt->m_tid != _tid) continue;

static std::set<std::string> _static_strings{};
std::string _last = {};
for(const auto& itr : _bt->get())
{
auto _name = tim::demangle(_patch_label(itr));
auto _use =
_use_label(_name, !_last.empty() &&
(_last == "start_thread" || _last == "clone"));
auto _use = _use_label(_name);
if(_use == -1) break;
if(_use == 0) continue;
auto sitr = _static_strings.emplace(_name);
_last = *sitr.first;
auto _ts = _bt->m_ts;
if(!pthread_create_gotcha::is_valid_execution_time(_tid, _ts)) continue;

TRACE_EVENT_BEGIN("hardware_counter",
perfetto::StaticString{ sitr.first->c_str() },
_last_wall_ts, "begin_ns", _last_wall_ts);
TRACE_EVENT_END("hardware_counter", _ts, "end_ns", _ts);
auto sitr = _static_strings.emplace(_name);
uint64_t _beg = _last_wall_ts;
uint64_t _end = _bt->m_ts;
if(_end <= _beg) continue;
if(!pthread_create_gotcha::is_valid_execution_time(_tid, _beg)) continue;
if(!pthread_create_gotcha::is_valid_execution_time(_tid, _end)) continue;

tracing::push_perfetto_ts(category::sampling{}, sitr.first->c_str(), _beg,
"begin_ns", _beg);
tracing::pop_perfetto_ts(category::sampling{}, sitr.first->c_str(), _end,
"end_ns", _end);
}
_last_wall_ts = _bt->m_ts;
}

tracing::pop_perfetto_ts(category::sampling{}, "samples [omnitrace]", _end_ns,
"end_ns", _end_ns);
};

auto _raw_data = _sampler->get_allocator().get_data();
Expand Down Expand Up @@ -648,14 +646,9 @@ backtrace::post_process(int64_t _tid)
{
_process_perfetto_counters(_data);

if(_tid == 0 && get_mode() == Mode::Sampling)
_process_perfetto(_data, false);
else
{
pthread_gotcha::push_enable_sampling_on_child_threads(false);
std::thread{ _process_perfetto, _data, true }.join();
pthread_gotcha::pop_enable_sampling_on_child_threads();
}
pthread_gotcha::push_enable_sampling_on_child_threads(false);
std::thread{ _process_perfetto, _data, true }.join();
pthread_gotcha::pop_enable_sampling_on_child_threads();
}

if(!get_use_timemory()) return;
Expand Down Expand Up @@ -685,10 +678,8 @@ backtrace::post_process(int64_t _tid)
// generate the instances of the tuple of components and start them
for(const auto& itr : _bt->get())
{
auto _lbl = _patch_label(itr);
auto _use =
_use_label(_lbl, !_tc.empty() && (_tc.back().key() == "start_thread" ||
_tc.back().key() == "clone"));
auto _lbl = tim::demangle(_patch_label(itr));
auto _use = _use_label(_lbl);
if(_use == -1) break;
if(_use == 0) continue;
_tc.emplace_back(tim::string_view_t{ _lbl }, _scope);
Expand Down Expand Up @@ -758,9 +749,8 @@ backtrace::post_process(int64_t _tid)
// generate the instances of the tuple of components and start them
for(const auto& itr : _bt->get())
{
auto _lbl = _patch_label(itr);
auto _use =
_use_label(_lbl, !_tc.empty() && _tc.back().key() == "start_thread");
auto _lbl = tim::demangle(_patch_label(itr));
auto _use = _use_label(_lbl);
if(_use == -1) break;
if(_use == 0) continue;
_tc.emplace_back(tim::string_view_t{ _lbl });
Expand Down
16 changes: 8 additions & 8 deletions source/lib/omnitrace/library/components/backtrace.hpp
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Original file line number Diff line number Diff line change
Expand Up @@ -81,14 +81,14 @@ struct backtrace
static void post_process(int64_t _tid = threading::get_id());
static hw_counter_data_t& get_last_hwcounters();

static void start();
static void stop();
void sample(int = -1);
bool empty() const;
size_t size() const;
std::vector<std::string> get() const;
uint64_t get_timestamp() const;
int64_t get_thread_cpu_timestamp() const;
static void start();
static void stop();
void sample(int = -1);
bool empty() const;
size_t size() const;
std::vector<std::string_view> get() const;
uint64_t get_timestamp() const;
int64_t get_thread_cpu_timestamp() const;

private:
int64_t m_tid = 0;
Expand Down
1 change: 1 addition & 0 deletions source/lib/omnitrace/library/perfetto.hpp
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Original file line number Diff line number Diff line change
Expand Up @@ -31,6 +31,7 @@
#define OMNITRACE_PERFETTO_CATEGORIES \
perfetto::Category("host").SetDescription("Host-side function tracing"), \
perfetto::Category("user").SetDescription("User-defined regions"), \
perfetto::Category("sampling").SetDescription("Host-side function sampling"), \
perfetto::Category("device_hip") \
.SetDescription("Device-side functions submitted via HSA API"), \
perfetto::Category("device_hsa") \
Expand Down