From 8003f553a01a9a2a7eb09fe07e88f1ba9ee7d3a7 Mon Sep 17 00:00:00 2001 From: Aiden Grossman Date: Tue, 12 Mar 2024 16:29:34 -0700 Subject: Reland "[llvm-exegesis] Add thread IDs to subprocess memory names (#84451)" This reverts commit aefad27096bba513f06162fac2763089578f3de4. This relands commit 6bbe8a296ee91754d423c59c35727eaa624f7140. This patch was casuing build failures on non-Linux platforms due to the default implementations for the functions not being updated. This ended up causing out-of-line definition errors. Fixed for the relanding. --- llvm/tools/llvm-exegesis/lib/BenchmarkRunner.cpp | 9 ++++--- llvm/tools/llvm-exegesis/lib/SubprocessMemory.cpp | 30 +++++++++++++++------- llvm/tools/llvm-exegesis/lib/SubprocessMemory.h | 5 +++- .../llvm-exegesis/X86/SubprocessMemoryTest.cpp | 5 +++- 4 files changed, 34 insertions(+), 15 deletions(-) diff --git a/llvm/tools/llvm-exegesis/lib/BenchmarkRunner.cpp b/llvm/tools/llvm-exegesis/lib/BenchmarkRunner.cpp index 5c9848f..4e97d18 100644 --- a/llvm/tools/llvm-exegesis/lib/BenchmarkRunner.cpp +++ b/llvm/tools/llvm-exegesis/lib/BenchmarkRunner.cpp @@ -301,6 +301,7 @@ private: if (AddMemDefError) return AddMemDefError; + long ParentTID = SubprocessMemory::getCurrentTID(); pid_t ParentOrChildPID = fork(); if (ParentOrChildPID == -1) { @@ -314,7 +315,7 @@ private: // Unregister handlers, signal handling is now handled through ptrace in // the host process. sys::unregisterHandlers(); - prepareAndRunBenchmark(PipeFiles[0], Key); + prepareAndRunBenchmark(PipeFiles[0], Key, ParentTID); // The child process terminates in the above function, so we should never // get to this point. llvm_unreachable("Child process didn't exit when expected."); @@ -415,8 +416,8 @@ private: setrlimit(RLIMIT_CORE, &rlim); } - [[noreturn]] void prepareAndRunBenchmark(int Pipe, - const BenchmarkKey &Key) const { + [[noreturn]] void prepareAndRunBenchmark(int Pipe, const BenchmarkKey &Key, + long ParentTID) const { // Disable core dumps in the child process as otherwise everytime we // encounter an execution failure like a segmentation fault, we will create // a core dump. We report the information directly rather than require the @@ -473,7 +474,7 @@ private: Expected AuxMemFDOrError = SubprocessMemory::setupAuxiliaryMemoryInSubprocess( - Key.MemoryValues, ParentPID, CounterFileDescriptor); + Key.MemoryValues, ParentPID, ParentTID, CounterFileDescriptor); if (!AuxMemFDOrError) exit(ChildProcessExitCodeE::AuxiliaryMemorySetupFailed); diff --git a/llvm/tools/llvm-exegesis/lib/SubprocessMemory.cpp b/llvm/tools/llvm-exegesis/lib/SubprocessMemory.cpp index a49fa077..1fd81bd 100644 --- a/llvm/tools/llvm-exegesis/lib/SubprocessMemory.cpp +++ b/llvm/tools/llvm-exegesis/lib/SubprocessMemory.cpp @@ -9,11 +9,13 @@ #include "SubprocessMemory.h" #include "Error.h" #include "llvm/Support/Error.h" +#include "llvm/Support/FormatVariadic.h" #include #ifdef __linux__ #include #include +#include #include #endif @@ -22,12 +24,21 @@ namespace exegesis { #if defined(__linux__) && !defined(__ANDROID__) +long SubprocessMemory::getCurrentTID() { + // We're using the raw syscall here rather than the gettid() function provided + // by most libcs for compatibility as gettid() was only added to glibc in + // version 2.30. + return syscall(SYS_gettid); +} + Error SubprocessMemory::initializeSubprocessMemory(pid_t ProcessID) { // Add the PID to the shared memory name so that if we're running multiple // processes at the same time, they won't interfere with each other. // This comes up particularly often when running the exegesis tests with - // llvm-lit - std::string AuxiliaryMemoryName = "/auxmem" + std::to_string(ProcessID); + // llvm-lit. Additionally add the TID so that downstream consumers + // using multiple threads don't run into conflicts. + std::string AuxiliaryMemoryName = + formatv("/{0}auxmem{1}", getCurrentTID(), ProcessID); int AuxiliaryMemoryFD = shm_open(AuxiliaryMemoryName.c_str(), O_RDWR | O_CREAT, S_IRUSR | S_IWUSR); if (AuxiliaryMemoryFD == -1) @@ -47,8 +58,8 @@ Error SubprocessMemory::addMemoryDefinition( pid_t ProcessPID) { SharedMemoryNames.reserve(MemoryDefinitions.size()); for (auto &[Name, MemVal] : MemoryDefinitions) { - std::string SharedMemoryName = "/" + std::to_string(ProcessPID) + "memdef" + - std::to_string(MemVal.Index); + std::string SharedMemoryName = + formatv("/{0}t{1}memdef{2}", ProcessPID, getCurrentTID(), MemVal.Index); SharedMemoryNames.push_back(SharedMemoryName); int SharedMemoryFD = shm_open(SharedMemoryName.c_str(), O_RDWR | O_CREAT, S_IRUSR | S_IWUSR); @@ -82,8 +93,9 @@ Error SubprocessMemory::addMemoryDefinition( Expected SubprocessMemory::setupAuxiliaryMemoryInSubprocess( std::unordered_map MemoryDefinitions, - pid_t ParentPID, int CounterFileDescriptor) { - std::string AuxiliaryMemoryName = "/auxmem" + std::to_string(ParentPID); + pid_t ParentPID, long ParentTID, int CounterFileDescriptor) { + std::string AuxiliaryMemoryName = + formatv("/{0}auxmem{1}", ParentTID, ParentPID); int AuxiliaryMemoryFileDescriptor = shm_open(AuxiliaryMemoryName.c_str(), O_RDWR, S_IRUSR | S_IWUSR); if (AuxiliaryMemoryFileDescriptor == -1) @@ -97,8 +109,8 @@ Expected SubprocessMemory::setupAuxiliaryMemoryInSubprocess( return make_error("Mapping auxiliary memory failed"); AuxiliaryMemoryMapping[0] = CounterFileDescriptor; for (auto &[Name, MemVal] : MemoryDefinitions) { - std::string MemoryValueName = "/" + std::to_string(ParentPID) + "memdef" + - std::to_string(MemVal.Index); + std::string MemoryValueName = + formatv("/{0}t{1}memdef{2}", ParentPID, ParentTID, MemVal.Index); AuxiliaryMemoryMapping[AuxiliaryMemoryOffset + MemVal.Index] = shm_open(MemoryValueName.c_str(), O_RDWR, S_IRUSR | S_IWUSR); if (AuxiliaryMemoryMapping[AuxiliaryMemoryOffset + MemVal.Index] == -1) @@ -133,7 +145,7 @@ Error SubprocessMemory::addMemoryDefinition( Expected SubprocessMemory::setupAuxiliaryMemoryInSubprocess( std::unordered_map MemoryDefinitions, - pid_t ParentPID, int CounterFileDescriptor) { + pid_t ParentPID, long ParentTID, int CounterFileDescriptor) { return make_error( "setupAuxiliaryMemoryInSubprocess is only supported on Linux"); } diff --git a/llvm/tools/llvm-exegesis/lib/SubprocessMemory.h b/llvm/tools/llvm-exegesis/lib/SubprocessMemory.h index e20b50c..572d108 100644 --- a/llvm/tools/llvm-exegesis/lib/SubprocessMemory.h +++ b/llvm/tools/llvm-exegesis/lib/SubprocessMemory.h @@ -35,6 +35,9 @@ public: static constexpr const size_t AuxiliaryMemoryOffset = 1; static constexpr const size_t AuxiliaryMemorySize = 4096; + // Gets the thread ID for the calling thread. + static long getCurrentTID(); + Error initializeSubprocessMemory(pid_t ProcessID); // The following function sets up memory definitions. It creates shared @@ -54,7 +57,7 @@ public: // section. static Expected setupAuxiliaryMemoryInSubprocess( std::unordered_map MemoryDefinitions, - pid_t ParentPID, int CounterFileDescriptor); + pid_t ParentPID, long ParentTID, int CounterFileDescriptor); ~SubprocessMemory(); diff --git a/llvm/unittests/tools/llvm-exegesis/X86/SubprocessMemoryTest.cpp b/llvm/unittests/tools/llvm-exegesis/X86/SubprocessMemoryTest.cpp index c07ec18..7c23e7b 100644 --- a/llvm/unittests/tools/llvm-exegesis/X86/SubprocessMemoryTest.cpp +++ b/llvm/unittests/tools/llvm-exegesis/X86/SubprocessMemoryTest.cpp @@ -17,6 +17,7 @@ #include #include #include +#include #include #endif // __linux__ @@ -49,7 +50,9 @@ protected: std::string getSharedMemoryName(const unsigned TestNumber, const unsigned DefinitionNumber) { - return "/" + std::to_string(getSharedMemoryNumber(TestNumber)) + "memdef" + + long CurrentTID = syscall(SYS_gettid); + return "/" + std::to_string(getSharedMemoryNumber(TestNumber)) + "t" + + std::to_string(CurrentTID) + "memdef" + std::to_string(DefinitionNumber); } -- cgit v1.1