[llvm] [llvm-exegesis] Add thread IDs to subprocess memory names (PR #84451)
Aiden Grossman via llvm-commits
llvm-commits at lists.llvm.org
Tue Mar 12 00:13:16 PDT 2024
https://github.com/boomanaiden154 updated https://github.com/llvm/llvm-project/pull/84451
>From edd2faabd6639ac44f1a0edc10deb3aed63b3e11 Mon Sep 17 00:00:00 2001
From: Aiden Grossman <agrossman154 at yahoo.com>
Date: Fri, 8 Mar 2024 02:02:52 -0800
Subject: [PATCH 1/3] [llvm-exegesis] Add thread IDs to subprocess memory names
This patch adds the thread ID to the subprocess memory shared memory
names. This avoids conflicts for downstream consumers that might want to
consume llvm-exegesis across multiple threads, which would otherwise run
into conflicts due to the same PID running multiple instances.
---
.../llvm-exegesis/lib/SubprocessMemory.cpp | 17 ++++++++++++++---
.../llvm-exegesis/X86/SubprocessMemoryTest.cpp | 5 ++++-
2 files changed, 18 insertions(+), 4 deletions(-)
diff --git a/llvm/tools/llvm-exegesis/lib/SubprocessMemory.cpp b/llvm/tools/llvm-exegesis/lib/SubprocessMemory.cpp
index a49fa077257d00..28dc4488a2a004 100644
--- a/llvm/tools/llvm-exegesis/lib/SubprocessMemory.cpp
+++ b/llvm/tools/llvm-exegesis/lib/SubprocessMemory.cpp
@@ -14,6 +14,7 @@
#ifdef __linux__
#include <fcntl.h>
#include <sys/mman.h>
+#include <sys/syscall.h>
#include <unistd.h>
#endif
@@ -22,12 +23,21 @@ namespace exegesis {
#if defined(__linux__) && !defined(__ANDROID__)
+long 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 = "/" + std::to_string(getCurrentTID()) +
+ "auxmem" + std::to_string(ProcessID);
int AuxiliaryMemoryFD = shm_open(AuxiliaryMemoryName.c_str(),
O_RDWR | O_CREAT, S_IRUSR | S_IWUSR);
if (AuxiliaryMemoryFD == -1)
@@ -47,7 +57,8 @@ Error SubprocessMemory::addMemoryDefinition(
pid_t ProcessPID) {
SharedMemoryNames.reserve(MemoryDefinitions.size());
for (auto &[Name, MemVal] : MemoryDefinitions) {
- std::string SharedMemoryName = "/" + std::to_string(ProcessPID) + "memdef" +
+ std::string SharedMemoryName = "/" + std::to_string(ProcessPID) + "t" +
+ std::to_string(getCurrentTID()) + "memdef" +
std::to_string(MemVal.Index);
SharedMemoryNames.push_back(SharedMemoryName);
int SharedMemoryFD =
diff --git a/llvm/unittests/tools/llvm-exegesis/X86/SubprocessMemoryTest.cpp b/llvm/unittests/tools/llvm-exegesis/X86/SubprocessMemoryTest.cpp
index c07ec188a602c4..7c23e7b7e9c5a5 100644
--- a/llvm/unittests/tools/llvm-exegesis/X86/SubprocessMemoryTest.cpp
+++ b/llvm/unittests/tools/llvm-exegesis/X86/SubprocessMemoryTest.cpp
@@ -17,6 +17,7 @@
#include <endian.h>
#include <fcntl.h>
#include <sys/mman.h>
+#include <sys/syscall.h>
#include <unistd.h>
#endif // __linux__
@@ -49,7 +50,9 @@ class SubprocessMemoryTest : public X86TestBase {
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);
}
>From ef960996a6f35477bcfcc0119fa562c7b0483ad0 Mon Sep 17 00:00:00 2001
From: Aiden Grossman <agrossman154 at yahoo.com>
Date: Mon, 11 Mar 2024 19:30:11 -0700
Subject: [PATCH 2/3] Finish plumbing TIDs
---
llvm/tools/llvm-exegesis/lib/BenchmarkRunner.cpp | 9 +++++----
llvm/tools/llvm-exegesis/lib/SubprocessMemory.cpp | 10 ++++++----
llvm/tools/llvm-exegesis/lib/SubprocessMemory.h | 5 ++++-
3 files changed, 15 insertions(+), 9 deletions(-)
diff --git a/llvm/tools/llvm-exegesis/lib/BenchmarkRunner.cpp b/llvm/tools/llvm-exegesis/lib/BenchmarkRunner.cpp
index 5c9848f3c68885..4e97d188d17259 100644
--- a/llvm/tools/llvm-exegesis/lib/BenchmarkRunner.cpp
+++ b/llvm/tools/llvm-exegesis/lib/BenchmarkRunner.cpp
@@ -301,6 +301,7 @@ class SubProcessFunctionExecutorImpl
if (AddMemDefError)
return AddMemDefError;
+ long ParentTID = SubprocessMemory::getCurrentTID();
pid_t ParentOrChildPID = fork();
if (ParentOrChildPID == -1) {
@@ -314,7 +315,7 @@ class SubProcessFunctionExecutorImpl
// 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 @@ class SubProcessFunctionExecutorImpl
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 @@ class SubProcessFunctionExecutorImpl
Expected<int> 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 28dc4488a2a004..d3966942b8dbe7 100644
--- a/llvm/tools/llvm-exegesis/lib/SubprocessMemory.cpp
+++ b/llvm/tools/llvm-exegesis/lib/SubprocessMemory.cpp
@@ -23,7 +23,7 @@ namespace exegesis {
#if defined(__linux__) && !defined(__ANDROID__)
-long getCurrentTID() {
+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.
@@ -93,8 +93,9 @@ Error SubprocessMemory::addMemoryDefinition(
Expected<int> SubprocessMemory::setupAuxiliaryMemoryInSubprocess(
std::unordered_map<std::string, MemoryValue> MemoryDefinitions,
- pid_t ParentPID, int CounterFileDescriptor) {
- std::string AuxiliaryMemoryName = "/auxmem" + std::to_string(ParentPID);
+ pid_t ParentPID, long ParentTID, int CounterFileDescriptor) {
+ std::string AuxiliaryMemoryName =
+ "/" + std::to_string(ParentTID) + "auxmem" + std::to_string(ParentPID);
int AuxiliaryMemoryFileDescriptor =
shm_open(AuxiliaryMemoryName.c_str(), O_RDWR, S_IRUSR | S_IWUSR);
if (AuxiliaryMemoryFileDescriptor == -1)
@@ -108,7 +109,8 @@ Expected<int> SubprocessMemory::setupAuxiliaryMemoryInSubprocess(
return make_error<Failure>("Mapping auxiliary memory failed");
AuxiliaryMemoryMapping[0] = CounterFileDescriptor;
for (auto &[Name, MemVal] : MemoryDefinitions) {
- std::string MemoryValueName = "/" + std::to_string(ParentPID) + "memdef" +
+ std::string MemoryValueName = "/" + std::to_string(ParentPID) + "t" +
+ std::to_string(ParentTID) + "memdef" +
std::to_string(MemVal.Index);
AuxiliaryMemoryMapping[AuxiliaryMemoryOffset + MemVal.Index] =
shm_open(MemoryValueName.c_str(), O_RDWR, S_IRUSR | S_IWUSR);
diff --git a/llvm/tools/llvm-exegesis/lib/SubprocessMemory.h b/llvm/tools/llvm-exegesis/lib/SubprocessMemory.h
index e20b50cdc8118f..572d1085d9cffa 100644
--- a/llvm/tools/llvm-exegesis/lib/SubprocessMemory.h
+++ b/llvm/tools/llvm-exegesis/lib/SubprocessMemory.h
@@ -35,6 +35,9 @@ class SubprocessMemory {
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 @@ class SubprocessMemory {
// section.
static Expected<int> setupAuxiliaryMemoryInSubprocess(
std::unordered_map<std::string, MemoryValue> MemoryDefinitions,
- pid_t ParentPID, int CounterFileDescriptor);
+ pid_t ParentPID, long ParentTID, int CounterFileDescriptor);
~SubprocessMemory();
>From 82a9e9d3e3598d8c095b498891fe0ba3f176b54c Mon Sep 17 00:00:00 2001
From: Aiden Grossman <agrossman154 at yahoo.com>
Date: Tue, 12 Mar 2024 00:13:06 -0700
Subject: [PATCH 3/3] Use llvm::formtatv
---
llvm/tools/llvm-exegesis/lib/SubprocessMemory.cpp | 12 ++++++------
1 file changed, 6 insertions(+), 6 deletions(-)
diff --git a/llvm/tools/llvm-exegesis/lib/SubprocessMemory.cpp b/llvm/tools/llvm-exegesis/lib/SubprocessMemory.cpp
index d3966942b8dbe7..a5f4b2db67649f 100644
--- a/llvm/tools/llvm-exegesis/lib/SubprocessMemory.cpp
+++ b/llvm/tools/llvm-exegesis/lib/SubprocessMemory.cpp
@@ -9,6 +9,7 @@
#include "SubprocessMemory.h"
#include "Error.h"
#include "llvm/Support/Error.h"
+#include "llvm/Support/FormatVariadic.h"
#include <cerrno>
#ifdef __linux__
@@ -36,8 +37,8 @@ Error SubprocessMemory::initializeSubprocessMemory(pid_t ProcessID) {
// This comes up particularly often when running the exegesis tests with
// llvm-lit. Additionally add the TID so that downstream consumers
// using multiple threads don't run into conflicts.
- std::string AuxiliaryMemoryName = "/" + std::to_string(getCurrentTID()) +
- "auxmem" + std::to_string(ProcessID);
+ std::string AuxiliaryMemoryName =
+ llvm::formatv("/{0}auxmem{1}", getCurrentTID(), ProcessID);
int AuxiliaryMemoryFD = shm_open(AuxiliaryMemoryName.c_str(),
O_RDWR | O_CREAT, S_IRUSR | S_IWUSR);
if (AuxiliaryMemoryFD == -1)
@@ -57,9 +58,8 @@ Error SubprocessMemory::addMemoryDefinition(
pid_t ProcessPID) {
SharedMemoryNames.reserve(MemoryDefinitions.size());
for (auto &[Name, MemVal] : MemoryDefinitions) {
- std::string SharedMemoryName = "/" + std::to_string(ProcessPID) + "t" +
- std::to_string(getCurrentTID()) + "memdef" +
- std::to_string(MemVal.Index);
+ std::string SharedMemoryName = llvm::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);
@@ -95,7 +95,7 @@ Expected<int> SubprocessMemory::setupAuxiliaryMemoryInSubprocess(
std::unordered_map<std::string, MemoryValue> MemoryDefinitions,
pid_t ParentPID, long ParentTID, int CounterFileDescriptor) {
std::string AuxiliaryMemoryName =
- "/" + std::to_string(ParentTID) + "auxmem" + std::to_string(ParentPID);
+ llvm::formatv("/{0}auxmem{1}", ParentTID, ParentPID);
int AuxiliaryMemoryFileDescriptor =
shm_open(AuxiliaryMemoryName.c_str(), O_RDWR, S_IRUSR | S_IWUSR);
if (AuxiliaryMemoryFileDescriptor == -1)
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