Otel allocation profiling POC

CMakeLists.txt

@@ -280,7 +280,8 @@ target_link_libraries(
   PRIVATE
     "$<$<AND:$<C_COMPILER_ID:GNU>,$<CONFIG:SanitizedDebug>>:-Wl,-Bstatic;-lubsan;-lasan;-lstdc++;-Wl,-Bdynamic>"
 )
-target_link_libraries(dd_profiling-embedded PUBLIC dl pthread rt absl::base absl::str_format)
+target_link_libraries(dd_profiling-embedded PUBLIC dl pthread rt absl::base absl::str_format
+                                                   systemtap)
 
 set(LIBDD_PROFILING_EMBEDDED_OBJECT "${CMAKE_BINARY_DIR}/libdd_profiling-embedded.o")
 set(LIBDD_PROFILING_EMBEDDED_HASH_HEADER "${CMAKE_BINARY_DIR}/libdd_profiling-embedded_hash.h")
@@ -365,7 +366,8 @@ target_include_directories(dd_profiling-static PUBLIC ${CMAKE_SOURCE_DIR}/includ
 set_target_properties(dd_profiling-static
                       PROPERTIES PUBLIC_HEADER "${CMAKE_SOURCE_DIR}/include/lib/dd_profiling.h")
 target_link_libraries(dd_profiling-static PRIVATE ddprof_exe_object)
-target_link_libraries(dd_profiling-static PUBLIC dl pthread rt absl::base absl::str_format)
+target_link_libraries(dd_profiling-static PUBLIC dl pthread rt absl::base absl::str_format
+                                                 systemtap)
 
 if(USE_LOADER)
   # When using a loader, libdd_profiling.so is a loader that embeds both libdd_profiling-embedded.so
@@ -398,7 +400,8 @@ else()
     PRIVATE
       "$<$<AND:$<C_COMPILER_ID:GNU>,$<CONFIG:SanitizedDebug>>:-Wl,-Bstatic;-lubsan;-lasan;-lstdc++;-Wl,-Bdynamic>"
   )
-  target_link_libraries(dd_profiling-shared PUBLIC dl pthread rt absl::base absl::str_format)
+  target_link_libraries(dd_profiling-shared PUBLIC dl pthread rt absl::base absl::str_format
+                                                   systemtap)
 endif()
 
 target_static_libcxx(dd_profiling-shared)

include/lib/allocation_tracker.hpp

@@ -35,7 +35,8 @@ class AllocationTracker {
 
   enum AllocationTrackingFlags {
     kTrackDeallocations = 0x1,
-    kDeterministicSampling = 0x2
+    kDeterministicSampling = 0x2,
+    kOtelProfilerMode = 0x4,
   };
 
   struct IntervalTimerCheck {
@@ -101,9 +102,8 @@ class AllocationTracker {
 
   uint64_t next_sample_interval(std::minstd_rand &gen) const;
 
-  DDRes init(uint64_t mem_profile_interval, bool deterministic_sampling,
-             bool track_deallocations, uint32_t stack_sample_size,
-             const RingBufferInfo &ring_buffer,
+  DDRes init(uint64_t mem_profile_interval, uint32_t flags,
+             uint32_t stack_sample_size, const RingBufferInfo &ring_buffer,
              const IntervalTimerCheck &timer_check);
   void free();
 
@@ -141,6 +141,7 @@ class AllocationTracker {
   uint32_t _stack_sample_size;
   PEvent _pevent;
   bool _deterministic_sampling;
+  bool _otel_profiler_mode;
 
   AddressBitset _allocated_address_set;
   IntervalTimerCheck _interval_timer_check;

src/lib/allocation_tracker.cc

@@ -21,6 +21,7 @@
 #include <atomic>
 #include <cassert>
 #include <cstdlib>
+#include <sys/sdt.h>
 #include <unistd.h>
 
 namespace ddprof {
@@ -100,45 +101,49 @@ DDRes AllocationTracker::allocation_tracking_init(
     DDRES_RETURN_ERROR_LOG(DD_WHAT_UKNW, "Allocation profiler already started");
   }
 
-  DDRES_CHECK_FWD(instance->init(allocation_profiling_rate,
-                                 flags & kDeterministicSampling,
-                                 flags & kTrackDeallocations, stack_sample_size,
-                                 ring_buffer, timer_check));
+  DDRES_CHECK_FWD(instance->init(allocation_profiling_rate, flags,
+                                 stack_sample_size, ring_buffer, timer_check));
   _instance = instance;
 
   state.init(true, flags & kTrackDeallocations);
 
   return {};
 }
 
-DDRes AllocationTracker::init(uint64_t mem_profile_interval,
-                              bool deterministic_sampling,
-                              bool track_deallocations,
+DDRes AllocationTracker::init(uint64_t mem_profile_interval, uint32_t flags,
                               uint32_t stack_sample_size,
                               const RingBufferInfo &ring_buffer,
                               const IntervalTimerCheck &timer_check) {
   _sampling_interval = mem_profile_interval;
-  _deterministic_sampling = deterministic_sampling;
+  _deterministic_sampling = flags & kDeterministicSampling;
   _stack_sample_size = stack_sample_size;
-  if (ring_buffer.ring_buffer_type !=
-      static_cast<int>(RingBufferType::kMPSCRingBuffer)) {
-    return ddres_error(DD_WHAT_PERFRB);
+  _otel_profiler_mode = flags & kOtelProfilerMode;
+
+  if (!_otel_profiler_mode) {
+    if (ring_buffer.ring_buffer_type !=
+        static_cast<int>(RingBufferType::kMPSCRingBuffer)) {
+      return ddres_error(DD_WHAT_PERFRB);
+    }
+
+    DDRES_CHECK_FWD(ddprof::ring_buffer_attach(ring_buffer, &_pevent));
+
+    const auto &rb = _pevent.rb;
+    if (rb.tsc_available) {
+      TscClock::init(TscClock::CalibrationParams{
+          .offset = TscClock::time_point{TscClock::duration{rb.time_zero}},
+          .mult = rb.time_mult,
+          .shift = rb.time_shift});
+    }
+    PerfClock::init(static_cast<PerfClockSource>(rb.perf_clock_source));
+  } else {
+    PerfClock::init(PerfClockSource::kClockMonotonic);
   }
-  if (track_deallocations) {
+
+  if (flags & kTrackDeallocations) {
     // 16 times as we want to probability of collision to be low enough
     _allocated_address_set = AddressBitset(liveallocation::kMaxTracked *
                                            k_ratio_max_elt_to_bitset_size);
   }
-  DDRES_CHECK_FWD(ddprof::ring_buffer_attach(ring_buffer, &_pevent));
-
-  const auto &rb = _pevent.rb;
-  if (rb.tsc_available) {
-    TscClock::init(TscClock::CalibrationParams{
-        .offset = TscClock::time_point{TscClock::duration{rb.time_zero}},
-        .mult = rb.time_mult,
-        .shift = rb.time_shift});
-  }
-  PerfClock::init(static_cast<PerfClockSource>(rb.perf_clock_source));
 
   _interval_timer_check = timer_check;
   if (_interval_timer_check.is_set()) {
@@ -282,6 +287,7 @@ void AllocationTracker::track_deallocation(uintptr_t addr,
 DDRes AllocationTracker::push_lost_sample(MPSCRingBufferWriter &writer,
                                           TrackerThreadLocalState &tl_state,
                                           bool &notify_needed) {
+  DDPROF_DCHECK_FATAL(!_otel_profiler_mode);
   auto lost_count = _state.lost_count.exchange(0, std::memory_order_acq_rel);
   if (lost_count == 0) {
     return {};
@@ -322,6 +328,12 @@ DDRes AllocationTracker::push_lost_sample(MPSCRingBufferWriter &writer,
 // Return true if consumer should be notified
 DDRes AllocationTracker::push_clear_live_allocation(
     TrackerThreadLocalState &tl_state) {
+  if (_otel_profiler_mode) {
+    // NOLINTNEXTLINE
+    DTRACE_PROBE(ddprof, clear_live_allocations);
+    check_timer(PerfClock::now(), tl_state);
+    return {};
+  }
   MPSCRingBufferWriter writer{&_pevent.rb};
   bool timeout = false;
 
@@ -361,6 +373,13 @@ DDRes AllocationTracker::push_clear_live_allocation(
 
 DDRes AllocationTracker::push_dealloc_sample(
     uintptr_t addr, TrackerThreadLocalState &tl_state) {
+  if (_otel_profiler_mode) {
+    // NOLINTNEXTLINE
+    DTRACE_PROBE1(ddprof, deallocation, addr);
+    check_timer(PerfClock::now(), tl_state);
+    return {};
+  }
+
   MPSCRingBufferWriter writer{&_pevent.rb};
   bool notify_consumer{false};
 
@@ -414,6 +433,13 @@ DDRes AllocationTracker::push_dealloc_sample(
 DDRes AllocationTracker::push_alloc_sample(uintptr_t addr,
                                            uint64_t allocated_size,
                                            TrackerThreadLocalState &tl_state) {
+  if (_otel_profiler_mode) {
+    // NOLINTNEXTLINE
+    DTRACE_PROBE2(ddprof, allocation, addr, allocated_size);
+    check_timer(PerfClock::now(), tl_state);
+    return {};
+  }
+
   MPSCRingBufferWriter writer{&_pevent.rb};
   bool notify_consumer{false};
 
@@ -427,12 +453,12 @@ DDRes AllocationTracker::push_alloc_sample(uintptr_t addr,
   const auto *stack_base_ptr = reinterpret_cast<const std::byte *>(&p);
   auto stack_size = to_address(tl_state.stack_bounds.end()) - stack_base_ptr;
 
-  // stack will be saved in save_context, add some margin to account for call
+  // stack will be saved in save_context, add some ` to account for call
   // frames
 #ifdef NDEBUG
   constexpr int64_t kStackMargin = 192;
 #else
-  constexpr int64_t kStackMargin = 720;
+  constexpr int64_t kStackMargin = 4000;
 #endif
   uint32_t const sample_stack_size =
       align_up(std::min(std::max(stack_size + kStackMargin, 0L),

src/lib/dd_profiling.cc

@@ -18,6 +18,7 @@
 #include "symbol_overrides.hpp"
 #include "syscalls.hpp"
 
+#include <absl/strings/numbers.h>
 #include <cassert>
 #include <cerrno>
 #include <charconv>
@@ -46,6 +47,7 @@ struct ProfilerState {
   bool allocation_profiling_started = false;
   bool follow_execs = true;
   pid_t profiler_pid = 0;
+  bool otel_profiler_mode = false;
 
   decltype(&::getenv) getenv = &::getenv;
   decltype(&::putenv) putenv = &::putenv;
@@ -151,6 +153,8 @@ void init_state() {
 
   auto *follow_execs_env = g_state.getenv(k_allocation_profiling_follow_execs);
   g_state.follow_execs = !(follow_execs_env && arg_no(follow_execs_env));
+  g_state.otel_profiler_mode =
+      g_state.getenv("DD_PROFILING_NATIVE_OTEL_MODE") != nullptr;
 
   init_logger();
   g_state.initialized = true;
@@ -323,6 +327,38 @@ int ddprof_start_profiling_internal() {
     return -1;
   }
 
+  if (g_state.otel_profiler_mode) {
+    auto *allocation_profiling_rate_str =
+        g_state.getenv("DD_PROFILING_NATIVE_ALLOCATION_PROFILING_RATE");
+    int64_t allocation_profiling_rate = 524288;
+    if (allocation_profiling_rate_str) {
+      (void)absl::SimpleAtoi(allocation_profiling_rate_str,
+                             &allocation_profiling_rate);
+    }
+    uint32_t flags = AllocationTracker::kOtelProfilerMode;
+    if (allocation_profiling_rate < 0) {
+      flags |= AllocationTracker::kDeterministicSampling;
+      allocation_profiling_rate = -allocation_profiling_rate;
+    }
+    constexpr std::chrono::milliseconds initial_loaded_libs_check_delay{5000};
+    constexpr std::chrono::milliseconds loaded_libs_check_interval{59000};
+
+    try {
+      if (IsDDResOK(AllocationTracker::allocation_tracking_init(
+              allocation_profiling_rate, flags, 0, RingBufferInfo{},
+              {update_overrides, initial_loaded_libs_check_delay,
+               loaded_libs_check_interval}))) {
+        setup_overrides();
+        g_state.allocation_profiling_started = true;
+      } else {
+        LG_ERR("Failed to start allocation profiling\n");
+        return -1;
+      }
+    } catch (const DDException &e) { return -1; }
+
+    return 0;
+  }
+
   auto socket_path = get_ddprof_socket_path();
   pid_t const target_pid = getpid();
 
@@ -398,6 +434,7 @@ int ddprof_start_profiling_internal() {
         g_state.allocation_profiling_started = true;
       } else {
         LG_ERR("Failed to start allocation profiling\n");
+        return -1;
       }
     }
   } catch (const DDException &e) { return -1; }

test/CMakeLists.txt

@@ -314,13 +314,19 @@ set(ALLOCATION_TRACKER_UT_SRCS
 
 add_unit_test(
   allocation_tracker-ut ${ALLOCATION_TRACKER_UT_SRCS}
-  LIBRARIES ${ELFUTILS_LIBRARIES} llvm-demangle dl rt Datadog::Profiling
+  LIBRARIES ${ELFUTILS_LIBRARIES} llvm-demangle dl rt Datadog::Profiling systemtap
   DEFINITIONS ${DDPROF_DEFINITION_LIST} KMAX_TRACKED_ALLOCATIONS=16384)
 
 if(TARGET jemalloc::jemalloc_shared)
   add_unit_test(
     allocation_tracker_jemalloc-ut ${ALLOCATION_TRACKER_UT_SRCS}
-    LIBRARIES ${ELFUTILS_LIBRARIES} llvm-demangle dl rt jemalloc::jemalloc_shared Datadog::Profiling
+    LIBRARIES ${ELFUTILS_LIBRARIES}
+              llvm-demangle
+              dl
+              rt
+              jemalloc::jemalloc_shared
+              Datadog::Profiling
+              systemtap
     DEFINITIONS ${DDPROF_DEFINITION_LIST} KMAX_TRACKED_ALLOCATIONS=16384 USE_JEMALLOC=1)
 endif()
 
@@ -431,7 +437,7 @@ add_benchmark(
   ../src/tsc_clock.cc
   ../src/user_override.cc
   ../src/sys_utils.cc
-  LIBRARIES ${ELFUTILS_LIBRARIES} llvm-demangle
+  LIBRARIES ${ELFUTILS_LIBRARIES} llvm-demangle systemtap
   DEFINITIONS ${DDPROF_DEFINITION_LIST} KMAX_TRACKED_ALLOCATIONS=16384)
 
 if(NOT CMAKE_BUILD_TYPE STREQUAL "SanitizedDebug")

third_party/CMakeLists.txt

@@ -1,2 +1,3 @@
 add_subdirectory(CLI)
 add_subdirectory(llvm)
+add_subdirectory(systemtap)

third_party/systemtap/CMakeLists.txt

@@ -0,0 +1,2 @@
+add_library(systemtap INTERFACE)
+target_include_directories(systemtap INTERFACE include/)

third_party/systemtap/include/sys/sdt-config.h

@@ -0,0 +1,6 @@
+/* @configure_input@
+
+   This file just defines _SDT_ASM_SECTION_AUTOGROUP_SUPPORT to 0 or 1 to
+   indicate whether the assembler supports "?" in .pushsection directives.  */
+
+#define _SDT_ASM_SECTION_AUTOGROUP_SUPPORT 1