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-rw-r--r--llvm/tools/llvm-exegesis/lib/BenchmarkRunner.cpp137
1 files changed, 81 insertions, 56 deletions
diff --git a/llvm/tools/llvm-exegesis/lib/BenchmarkRunner.cpp b/llvm/tools/llvm-exegesis/lib/BenchmarkRunner.cpp
index 5c9848f3c688..498308e2edbe 100644
--- a/llvm/tools/llvm-exegesis/lib/BenchmarkRunner.cpp
+++ b/llvm/tools/llvm-exegesis/lib/BenchmarkRunner.cpp
@@ -278,59 +278,20 @@ private:
return FD;
}
- Error createSubProcessAndRunBenchmark(
- StringRef CounterName, SmallVectorImpl<int64_t> &CounterValues,
- ArrayRef<const char *> ValidationCounters,
- SmallVectorImpl<int64_t> &ValidationCounterValues) const {
- int PipeFiles[2];
- int PipeSuccessOrErr = socketpair(AF_UNIX, SOCK_DGRAM, 0, PipeFiles);
- if (PipeSuccessOrErr != 0) {
- return make_error<Failure>(
- "Failed to create a pipe for interprocess communication between "
- "llvm-exegesis and the benchmarking subprocess: " +
- Twine(strerror(errno)));
- }
-
- SubprocessMemory SPMemory;
- Error MemoryInitError = SPMemory.initializeSubprocessMemory(getpid());
- if (MemoryInitError)
- return MemoryInitError;
-
- Error AddMemDefError =
- SPMemory.addMemoryDefinition(Key.MemoryValues, getpid());
- if (AddMemDefError)
- return AddMemDefError;
-
- pid_t ParentOrChildPID = fork();
-
- if (ParentOrChildPID == -1) {
- return make_error<Failure>("Failed to create child process: " +
- Twine(strerror(errno)));
- }
-
- if (ParentOrChildPID == 0) {
- // We are in the child process, close the write end of the pipe.
- close(PipeFiles[1]);
- // Unregister handlers, signal handling is now handled through ptrace in
- // the host process.
- sys::unregisterHandlers();
- prepareAndRunBenchmark(PipeFiles[0], Key);
- // 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.");
- }
-
+ Error
+ runParentProcess(pid_t ChildPID, int WriteFD, StringRef CounterName,
+ SmallVectorImpl<int64_t> &CounterValues,
+ ArrayRef<const char *> ValidationCounters,
+ SmallVectorImpl<int64_t> &ValidationCounterValues) const {
const ExegesisTarget &ET = State.getExegesisTarget();
- auto CounterOrError = ET.createCounter(
- CounterName, State, ValidationCounters, ParentOrChildPID);
+ auto CounterOrError =
+ ET.createCounter(CounterName, State, ValidationCounters, ChildPID);
if (!CounterOrError)
return CounterOrError.takeError();
pfm::CounterGroup *Counter = CounterOrError.get().get();
- close(PipeFiles[0]);
-
// Make sure to attach to the process (and wait for the sigstop to be
// delivered and for the process to continue) before we write to the counter
// file descriptor. Attaching to the process before writing to the socket
@@ -338,30 +299,30 @@ private:
// attach afterwards, the subprocess might exit before we get to the attach
// call due to effects like scheduler contention, introducing transient
// failures.
- if (ptrace(PTRACE_ATTACH, ParentOrChildPID, NULL, NULL) != 0)
+ if (ptrace(PTRACE_ATTACH, ChildPID, NULL, NULL) != 0)
return make_error<Failure>("Failed to attach to the child process: " +
Twine(strerror(errno)));
- if (wait(NULL) == -1) {
+ if (waitpid(ChildPID, NULL, 0) == -1) {
return make_error<Failure>(
"Failed to wait for child process to stop after attaching: " +
Twine(strerror(errno)));
}
- if (ptrace(PTRACE_CONT, ParentOrChildPID, NULL, NULL) != 0)
+ if (ptrace(PTRACE_CONT, ChildPID, NULL, NULL) != 0)
return make_error<Failure>(
"Failed to continue execution of the child process: " +
Twine(strerror(errno)));
int CounterFileDescriptor = Counter->getFileDescriptor();
Error SendError =
- sendFileDescriptorThroughSocket(PipeFiles[1], CounterFileDescriptor);
+ sendFileDescriptorThroughSocket(WriteFD, CounterFileDescriptor);
if (SendError)
return SendError;
int ChildStatus;
- if (wait(&ChildStatus) == -1) {
+ if (waitpid(ChildPID, &ChildStatus, 0) == -1) {
return make_error<Failure>(
"Waiting for the child process to complete failed: " +
Twine(strerror(errno)));
@@ -395,12 +356,25 @@ private:
// An error was encountered running the snippet, process it
siginfo_t ChildSignalInfo;
- if (ptrace(PTRACE_GETSIGINFO, ParentOrChildPID, NULL, &ChildSignalInfo) ==
- -1) {
+ if (ptrace(PTRACE_GETSIGINFO, ChildPID, NULL, &ChildSignalInfo) == -1) {
return make_error<Failure>("Getting signal info from the child failed: " +
Twine(strerror(errno)));
}
+ // Send SIGKILL rather than SIGTERM as the child process has no SIGTERM
+ // handlers to run, and calling SIGTERM would mean that ptrace will force
+ // it to block in the signal-delivery-stop for the SIGSEGV/other signals,
+ // and upon exit.
+ if (kill(ChildPID, SIGKILL) == -1)
+ return make_error<Failure>("Failed to kill child benchmarking proces: " +
+ Twine(strerror(errno)));
+
+ // Wait for the process to exit so that there are no zombie processes left
+ // around.
+ if (waitpid(ChildPID, NULL, 0) == -1)
+ return make_error<Failure>("Failed to wait for process to die: " +
+ Twine(strerror(errno)));
+
if (ChildSignalInfo.si_signo == SIGSEGV)
return make_error<SnippetSegmentationFault>(
reinterpret_cast<intptr_t>(ChildSignalInfo.si_addr));
@@ -408,6 +382,57 @@ private:
return make_error<SnippetSignal>(ChildSignalInfo.si_signo);
}
+ Error createSubProcessAndRunBenchmark(
+ StringRef CounterName, SmallVectorImpl<int64_t> &CounterValues,
+ ArrayRef<const char *> ValidationCounters,
+ SmallVectorImpl<int64_t> &ValidationCounterValues) const {
+ int PipeFiles[2];
+ int PipeSuccessOrErr = socketpair(AF_UNIX, SOCK_DGRAM, 0, PipeFiles);
+ if (PipeSuccessOrErr != 0) {
+ return make_error<Failure>(
+ "Failed to create a pipe for interprocess communication between "
+ "llvm-exegesis and the benchmarking subprocess: " +
+ Twine(strerror(errno)));
+ }
+
+ SubprocessMemory SPMemory;
+ Error MemoryInitError = SPMemory.initializeSubprocessMemory(getpid());
+ if (MemoryInitError)
+ return MemoryInitError;
+
+ Error AddMemDefError =
+ SPMemory.addMemoryDefinition(Key.MemoryValues, getpid());
+ if (AddMemDefError)
+ return AddMemDefError;
+
+ long ParentTID = SubprocessMemory::getCurrentTID();
+ pid_t ParentOrChildPID = fork();
+
+ if (ParentOrChildPID == -1) {
+ return make_error<Failure>("Failed to create child process: " +
+ Twine(strerror(errno)));
+ }
+
+ if (ParentOrChildPID == 0) {
+ // We are in the child process, close the write end of the pipe.
+ close(PipeFiles[1]);
+ // Unregister handlers, signal handling is now handled through ptrace in
+ // the host process.
+ sys::unregisterHandlers();
+ runChildSubprocess(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.");
+ }
+
+ // Close the read end of the pipe as we only need to write to the subprocess
+ // from the parent process.
+ close(PipeFiles[0]);
+ return runParentProcess(ParentOrChildPID, PipeFiles[1], CounterName,
+ CounterValues, ValidationCounters,
+ ValidationCounterValues);
+ }
+
void disableCoreDumps() const {
struct rlimit rlim;
@@ -415,8 +440,8 @@ private:
setrlimit(RLIMIT_CORE, &rlim);
}
- [[noreturn]] void prepareAndRunBenchmark(int Pipe,
- const BenchmarkKey &Key) const {
+ [[noreturn]] void runChildSubprocess(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 +498,7 @@ private:
Expected<int> AuxMemFDOrError =
SubprocessMemory::setupAuxiliaryMemoryInSubprocess(
- Key.MemoryValues, ParentPID, CounterFileDescriptor);
+ Key.MemoryValues, ParentPID, ParentTID, CounterFileDescriptor);
if (!AuxMemFDOrError)
exit(ChildProcessExitCodeE::AuxiliaryMemorySetupFailed);
generated by cgit v1.2.3 (git 2.25.1) at 2026-05-31 10:12:41 +0000