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-rw-r--r--lib/esan/CMakeLists.txt1
-rw-r--r--lib/esan/esan_flags.inc18
-rw-r--r--lib/esan/esan_sideline.h61
-rw-r--r--lib/esan/esan_sideline_linux.cpp170
-rw-r--r--lib/esan/working_set.cpp23
5 files changed, 272 insertions, 1 deletions
diff --git a/lib/esan/CMakeLists.txt b/lib/esan/CMakeLists.txt
index ac994d949..573d7d456 100644
--- a/lib/esan/CMakeLists.txt
+++ b/lib/esan/CMakeLists.txt
@@ -13,6 +13,7 @@ set(ESAN_SOURCES
esan_interface.cpp
esan_interceptors.cpp
esan_linux.cpp
+ esan_sideline_linux.cpp
cache_frag.cpp
working_set.cpp
working_set_posix.cpp)
diff --git a/lib/esan/esan_flags.inc b/lib/esan/esan_flags.inc
index f79fe9bf2..f8a95267f 100644
--- a/lib/esan/esan_flags.inc
+++ b/lib/esan/esan_flags.inc
@@ -18,8 +18,24 @@
// ESAN_FLAG(Type, Name, DefaultValue, Description)
// See COMMON_FLAG in sanitizer_flags.inc for more details.
-// Cross-tool options:
+//===----------------------------------------------------------------------===//
+// Cross-tool options
+//===----------------------------------------------------------------------===//
+
ESAN_FLAG(int, cache_line_size, 64,
"The number of bytes in a cache line. For the working-set tool, this "
"cannot be changed without also changing the compiler "
"instrumentation.")
+
+//===----------------------------------------------------------------------===//
+// Working set tool options
+//===----------------------------------------------------------------------===//
+
+ESAN_FLAG(bool, record_snapshots, true,
+ "Working set tool: whether to sample snapshots during a run.")
+
+// Typical profiling uses a 10ms timer. Our snapshots take some work
+// to scan memory so we reduce to 20ms.
+// To disable samples, turn off record_snapshots.
+ESAN_FLAG(int, sample_freq, 20,
+ "Working set tool: sampling frequency in milliseconds.")
diff --git a/lib/esan/esan_sideline.h b/lib/esan/esan_sideline.h
new file mode 100644
index 000000000..aa3fae1db
--- /dev/null
+++ b/lib/esan/esan_sideline.h
@@ -0,0 +1,61 @@
+//===-- esan_sideline.h -----------------------------------------*- C++ -*-===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file is a part of EfficiencySanitizer, a family of performance tuners.
+//
+// Esan sideline thread support.
+//===----------------------------------------------------------------------===//
+
+#ifndef ESAN_SIDELINE_H
+#define ESAN_SIDELINE_H
+
+#include "sanitizer_common/sanitizer_atomic.h"
+#include "sanitizer_common/sanitizer_internal_defs.h"
+
+namespace __esan {
+
+typedef void (*SidelineFunc)(void *Arg);
+
+// Currently only one sideline thread is supported.
+// It calls the SidelineFunc passed to launchThread once on each sample at the
+// given frequency in real time (i.e., wall clock time).
+class SidelineThread {
+public:
+ // We cannot initialize any fields in the constructor as it will be called
+ // *after* launchThread for a static instance, as esan.module_ctor is called
+ // before static initializers.
+ SidelineThread() {}
+ ~SidelineThread() {}
+
+ // To simplify declaration in sanitizer code where we want to avoid
+ // heap allocations, the constructor and destructor do nothing and
+ // launchThread and joinThread do the real work.
+ // They should each be called just once.
+ bool launchThread(SidelineFunc takeSample, void *Arg, u32 FreqMilliSec);
+ bool joinThread();
+
+ // Must be called from the sideline thread itself.
+ bool adjustTimer(u32 FreqMilliSec);
+
+private:
+ static int runSideline(void *Arg);
+ static void registerSignal(int SigNum);
+ static void handleSidelineSignal(int SigNum, void *SigInfo, void *Ctx);
+
+ char *Stack;
+ SidelineFunc sampleFunc;
+ void *FuncArg;
+ u32 Freq;
+ uptr SidelineId;
+ atomic_uintptr_t SidelineExit;
+};
+
+} // namespace __esan
+
+#endif // ESAN_SIDELINE_H
diff --git a/lib/esan/esan_sideline_linux.cpp b/lib/esan/esan_sideline_linux.cpp
new file mode 100644
index 000000000..ba4fe62f5
--- /dev/null
+++ b/lib/esan/esan_sideline_linux.cpp
@@ -0,0 +1,170 @@
+//===-- esan_sideline_linux.cpp ---------------------------------*- C++ -*-===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file is a part of EfficiencySanitizer, a family of performance tuners.
+//
+// Support for a separate or "sideline" tool thread on Linux.
+//===----------------------------------------------------------------------===//
+
+#include "sanitizer_common/sanitizer_platform.h"
+#if SANITIZER_LINUX
+
+#include "esan_sideline.h"
+#include "sanitizer_common/sanitizer_atomic.h"
+#include "sanitizer_common/sanitizer_common.h"
+#include "sanitizer_common/sanitizer_linux.h"
+#include <errno.h>
+#include <sched.h>
+#include <sys/prctl.h>
+#include <sys/signal.h>
+#include <sys/time.h>
+#include <sys/types.h>
+#include <sys/wait.h>
+
+namespace __esan {
+
+static const int SigAltStackSize = 4*1024;
+static const int SidelineStackSize = 4*1024;
+
+// FIXME: we'll need some kind of TLS (can we trust that a pthread key will
+// work in our non-POSIX thread?) to access our data in our signal handler
+// with multiple sideline threads. For now we assume there is only one
+// sideline thread and we use a dirty solution of a global var.
+static SidelineThread *TheThread;
+
+// We aren't passing SA_NODEFER so the same signal is blocked while here.
+void SidelineThread::handleSidelineSignal(int SigNum, void *SigInfo,
+ void *Ctx) {
+ VPrintf(3, "Sideline signal %d\n", SigNum);
+ CHECK_EQ(SigNum, SIGALRM);
+ // See above about needing TLS to avoid this global var.
+ SidelineThread *Thread = TheThread;
+ if (atomic_load(&Thread->SidelineExit, memory_order_relaxed) != 0)
+ return;
+ Thread->sampleFunc(Thread->FuncArg);
+}
+
+void SidelineThread::registerSignal(int SigNum) {
+ __sanitizer_sigaction SigAct;
+ internal_memset(&SigAct, 0, sizeof(SigAct));
+ SigAct.sigaction = handleSidelineSignal;
+ // We do not pass SA_NODEFER as we want to block the same signal.
+ SigAct.sa_flags = SA_ONSTACK | SA_SIGINFO;
+ int Res = internal_sigaction(SigNum, &SigAct, nullptr);
+ CHECK_EQ(Res, 0);
+}
+
+int SidelineThread::runSideline(void *Arg) {
+ VPrintf(1, "Sideline thread starting\n");
+ SidelineThread *Thread = static_cast<SidelineThread*>(Arg);
+
+ // If the parent dies, we want to exit also.
+ internal_prctl(PR_SET_PDEATHSIG, SIGKILL, 0, 0, 0);
+
+ // Set up a signal handler on an alternate stack for safety.
+ InternalScopedBuffer<char> StackMap(SigAltStackSize);
+ struct sigaltstack SigAltStack;
+ SigAltStack.ss_sp = StackMap.data();
+ SigAltStack.ss_size = SigAltStackSize;
+ SigAltStack.ss_flags = 0;
+ internal_sigaltstack(&SigAltStack, nullptr);
+
+ // We inherit the signal mask from the app thread. In case
+ // we weren't created at init time, we ensure the mask is empty.
+ __sanitizer_sigset_t SigSet;
+ internal_sigfillset(&SigSet);
+ int Res = internal_sigprocmask(SIG_UNBLOCK, &SigSet, nullptr);
+ CHECK_EQ(Res, 0);
+
+ registerSignal(SIGALRM);
+
+ bool TimerSuccess = Thread->adjustTimer(Thread->Freq);
+ CHECK(TimerSuccess);
+
+ // We loop, doing nothing but handling itimer signals.
+ while (atomic_load(&TheThread->SidelineExit, memory_order_relaxed) == 0)
+ sched_yield();
+
+ if (!Thread->adjustTimer(0))
+ VPrintf(1, "Failed to disable timer\n");
+
+ VPrintf(1, "Sideline thread exiting\n");
+ return 0;
+}
+
+bool SidelineThread::launchThread(SidelineFunc takeSample, void *Arg,
+ u32 FreqMilliSec) {
+ // This can only be called once. However, we can't clear a field in
+ // the constructor and check for that here as the constructor for
+ // a static instance is called *after* our module_ctor and thus after
+ // this routine! Thus we rely on the TheThread check below.
+ CHECK(TheThread == nullptr); // Only one sideline thread is supported.
+ TheThread = this;
+ sampleFunc = takeSample;
+ FuncArg = Arg;
+ Freq = FreqMilliSec;
+ atomic_store(&SidelineExit, 0, memory_order_relaxed);
+
+ // We do without a guard page.
+ Stack = static_cast<char*>(MmapOrDie(SidelineStackSize, "SidelineStack"));
+ // By omitting CLONE_THREAD, the child is in its own thread group and will not
+ // receive any of the application's signals.
+ SidelineId = internal_clone(
+ runSideline, Stack + SidelineStackSize,
+ CLONE_VM | CLONE_FS | CLONE_FILES | CLONE_UNTRACED,
+ this, nullptr /* parent_tidptr */,
+ nullptr /* newtls */, nullptr /* child_tidptr */);
+ int ErrCode;
+ if (internal_iserror(SidelineId, &ErrCode)) {
+ Printf("FATAL: EfficiencySanitizer failed to spawn a thread (code %d).\n",
+ ErrCode);
+ Die();
+ return false; // Not reached.
+ }
+ return true;
+}
+
+bool SidelineThread::joinThread() {
+ VPrintf(1, "Joining sideline thread\n");
+ bool Res = true;
+ atomic_store(&SidelineExit, 1, memory_order_relaxed);
+ while (true) {
+ uptr Status = internal_waitpid(SidelineId, nullptr, __WALL);
+ int ErrCode;
+ if (!internal_iserror(Status, &ErrCode))
+ break;
+ if (ErrCode == EINTR)
+ continue;
+ VPrintf(1, "Failed to join sideline thread (errno %d)\n", ErrCode);
+ Res = false;
+ break;
+ }
+ UnmapOrDie(Stack, SidelineStackSize);
+ return Res;
+}
+
+// Must be called from the sideline thread itself.
+bool SidelineThread::adjustTimer(u32 FreqMilliSec) {
+ CHECK(internal_getpid() == SidelineId);
+ Freq = FreqMilliSec;
+ struct itimerval TimerVal;
+ TimerVal.it_interval.tv_sec = (time_t) Freq / 1000;
+ TimerVal.it_interval.tv_usec = (time_t) (Freq % 1000) * 1000;
+ TimerVal.it_value.tv_sec = (time_t) Freq / 1000;
+ TimerVal.it_value.tv_usec = (time_t) (Freq % 1000) * 1000;
+ // As we're in a different thread group, we cannot use either
+ // ITIMER_PROF or ITIMER_VIRTUAL without taking up scheduled
+ // time ourselves: thus we must use real time.
+ int Res = setitimer(ITIMER_REAL, &TimerVal, nullptr);
+ return (Res == 0);
+}
+
+} // namespace __esan
+
+#endif // SANITIZER_LINUX
diff --git a/lib/esan/working_set.cpp b/lib/esan/working_set.cpp
index dcd683737..f4ed8a17e 100644
--- a/lib/esan/working_set.cpp
+++ b/lib/esan/working_set.cpp
@@ -16,6 +16,7 @@
#include "esan.h"
#include "esan_flags.h"
#include "esan_shadow.h"
+#include "esan_sideline.h"
#include "sanitizer_common/sanitizer_procmaps.h"
// We shadow every cache line of app memory with one shadow byte.
@@ -40,6 +41,12 @@ static const u32 CurWorkingSetBitIdx = 0;
static const byte ShadowAccessedVal =
(1 << TotalWorkingSetBitIdx) | (1 << CurWorkingSetBitIdx);
+static SidelineThread Thread;
+// If we use real-time-based timer samples this won't overflow in any realistic
+// scenario, but if we switch to some other unit (such as memory accesses) we
+// may want to consider a 64-bit int.
+static u32 SnapshotNum;
+
void processRangeAccessWorkingSet(uptr PC, uptr Addr, SIZE_T Size,
bool IsWrite) {
if (Size == 0)
@@ -124,9 +131,22 @@ static u32 computeWorkingSizeAndReset(u32 BitIdx) {
return WorkingSetSize;
}
+// This is invoked from a signal handler but in a sideline thread doing nothing
+// else so it is a little less fragile than a typical signal handler.
+static void takeSample(void *Arg) {
+ // FIXME: record the size and report at process end. For now this simply
+ // serves as a test of the sideline thread functionality.
+ VReport(1, "%s: snapshot #%d: %u\n", SanitizerToolName, SnapshotNum,
+ computeWorkingSizeAndReset(CurWorkingSetBitIdx));
+ ++SnapshotNum;
+}
+
void initializeWorkingSet() {
CHECK(getFlags()->cache_line_size == CacheLineSize);
registerMemoryFaultHandler();
+
+ if (getFlags()->record_snapshots)
+ Thread.launchThread(takeSample, nullptr, getFlags()->sample_freq);
}
static u32 getSizeForPrinting(u32 NumOfCachelines, const char *&Unit) {
@@ -147,6 +167,9 @@ static u32 getSizeForPrinting(u32 NumOfCachelines, const char *&Unit) {
}
int finalizeWorkingSet() {
+ if (getFlags()->record_snapshots)
+ Thread.joinThread();
+
// Get the working set size for the entire execution.
u32 NumOfCachelines = computeWorkingSizeAndReset(TotalWorkingSetBitIdx);
const char *Unit;
generated by cgit v1.2.3 (git 2.25.1) at 2024-06-08 12:07:20 +0000