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-rw-r--r--absl/synchronization/BUILD.bazel29
-rw-r--r--absl/synchronization/internal/graphcycles.cc28
-rw-r--r--absl/synchronization/internal/graphcycles_benchmark.cc46
-rw-r--r--absl/synchronization/mutex.cc19
-rw-r--r--absl/synchronization/mutex_benchmark.cc96
5 files changed, 188 insertions, 30 deletions
diff --git a/absl/synchronization/BUILD.bazel b/absl/synchronization/BUILD.bazel
index 05376903..67ce7ff9 100644
--- a/absl/synchronization/BUILD.bazel
+++ b/absl/synchronization/BUILD.bazel
@@ -39,6 +39,7 @@ cc_library(
],
deps = [
"//absl/base",
+ "//absl/base:base_internal",
"//absl/base:core_headers",
"//absl/base:malloc_internal",
],
@@ -119,6 +120,20 @@ cc_test(
],
)
+cc_test(
+ name = "graphcycles_benchmark",
+ srcs = ["internal/graphcycles_benchmark.cc"],
+ copts = ABSL_TEST_COPTS,
+ tags = [
+ "benchmark",
+ ],
+ deps = [
+ ":graphcycles_internal",
+ "//absl/base",
+ "@com_github_google_benchmark//:benchmark",
+ ],
+)
+
cc_library(
name = "thread_pool",
testonly = 1,
@@ -149,6 +164,20 @@ cc_test(
)
cc_test(
+ name = "mutex_benchmark",
+ srcs = ["mutex_benchmark.cc"],
+ copts = ABSL_TEST_COPTS,
+ tags = ["benchmark"],
+ visibility = ["//visibility:private"],
+ deps = [
+ ":synchronization",
+ ":thread_pool",
+ "//absl/base",
+ "@com_github_google_benchmark//:benchmark",
+ ],
+)
+
+cc_test(
name = "notification_test",
size = "small",
srcs = ["notification_test.cc"],
diff --git a/absl/synchronization/internal/graphcycles.cc b/absl/synchronization/internal/graphcycles.cc
index 28ad172c..ab1f3f84 100644
--- a/absl/synchronization/internal/graphcycles.cc
+++ b/absl/synchronization/internal/graphcycles.cc
@@ -37,6 +37,7 @@
#include <algorithm>
#include <array>
+#include "absl/base/internal/hide_ptr.h"
#include "absl/base/internal/raw_logging.h"
#include "absl/base/internal/spinlock.h"
@@ -276,18 +277,6 @@ inline uint32_t NodeVersion(GraphId id) {
return static_cast<uint32_t>(id.handle >> 32);
}
-// We need to hide Mutexes (or other deadlock detection's pointers)
-// from the leak detector. Xor with an arbitrary number with high bits set.
-static const uintptr_t kHideMask = static_cast<uintptr_t>(0xF03A5F7BF03A5F7Bll);
-
-static inline uintptr_t MaskPtr(void *ptr) {
- return reinterpret_cast<uintptr_t>(ptr) ^ kHideMask;
-}
-
-static inline void* UnmaskPtr(uintptr_t word) {
- return reinterpret_cast<void*>(word ^ kHideMask);
-}
-
struct Node {
int32_t rank; // rank number assigned by Pearce-Kelly algorithm
uint32_t version; // Current version number
@@ -309,7 +298,7 @@ class PointerMap {
}
int32_t Find(void* ptr) {
- auto masked = MaskPtr(ptr);
+ auto masked = base_internal::HidePtr(ptr);
for (int32_t i = table_[Hash(ptr)]; i != -1;) {
Node* n = (*nodes_)[i];
if (n->masked_ptr == masked) return i;
@@ -327,7 +316,7 @@ class PointerMap {
int32_t Remove(void* ptr) {
// Advance through linked list while keeping track of the
// predecessor slot that points to the current entry.
- auto masked = MaskPtr(ptr);
+ auto masked = base_internal::HidePtr(ptr);
for (int32_t* slot = &table_[Hash(ptr)]; *slot != -1; ) {
int32_t index = *slot;
Node* n = (*nodes_)[index];
@@ -395,7 +384,7 @@ bool GraphCycles::CheckInvariants() const {
NodeSet ranks; // Set of ranks seen so far.
for (uint32_t x = 0; x < r->nodes_.size(); x++) {
Node* nx = r->nodes_[x];
- void* ptr = UnmaskPtr(nx->masked_ptr);
+ void* ptr = base_internal::UnhidePtr<void>(nx->masked_ptr);
if (ptr != nullptr && static_cast<uint32_t>(r->ptrmap_.Find(ptr)) != x) {
ABSL_RAW_LOG(FATAL, "Did not find live node in hash table %u %p", x, ptr);
}
@@ -427,7 +416,7 @@ GraphId GraphCycles::GetId(void* ptr) {
n->version = 1; // Avoid 0 since it is used by InvalidGraphId()
n->visited = false;
n->rank = rep_->nodes_.size();
- n->masked_ptr = MaskPtr(ptr);
+ n->masked_ptr = base_internal::HidePtr(ptr);
n->nstack = 0;
n->priority = 0;
rep_->nodes_.push_back(n);
@@ -439,7 +428,7 @@ GraphId GraphCycles::GetId(void* ptr) {
int32_t r = rep_->free_nodes_.back();
rep_->free_nodes_.pop_back();
Node* n = rep_->nodes_[r];
- n->masked_ptr = MaskPtr(ptr);
+ n->masked_ptr = base_internal::HidePtr(ptr);
n->nstack = 0;
n->priority = 0;
rep_->ptrmap_.Add(ptr, r);
@@ -461,7 +450,7 @@ void GraphCycles::RemoveNode(void* ptr) {
}
x->in.clear();
x->out.clear();
- x->masked_ptr = MaskPtr(nullptr);
+ x->masked_ptr = base_internal::HidePtr<void>(nullptr);
if (x->version == std::numeric_limits<uint32_t>::max()) {
// Cannot use x any more
} else {
@@ -472,7 +461,8 @@ void GraphCycles::RemoveNode(void* ptr) {
void* GraphCycles::Ptr(GraphId id) {
Node* n = FindNode(rep_, id);
- return n == nullptr ? nullptr : UnmaskPtr(n->masked_ptr);
+ return n == nullptr ? nullptr
+ : base_internal::UnhidePtr<void>(n->masked_ptr);
}
bool GraphCycles::HasNode(GraphId node) {
diff --git a/absl/synchronization/internal/graphcycles_benchmark.cc b/absl/synchronization/internal/graphcycles_benchmark.cc
new file mode 100644
index 00000000..b4a1debe
--- /dev/null
+++ b/absl/synchronization/internal/graphcycles_benchmark.cc
@@ -0,0 +1,46 @@
+// Copyright 2018 The Abseil Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "absl/synchronization/internal/graphcycles.h"
+
+#include <algorithm>
+#include <cstdint>
+#include <vector>
+
+#include "benchmark/benchmark.h"
+#include "absl/base/internal/raw_logging.h"
+
+namespace {
+
+void BM_StressTest(benchmark::State& state) {
+ const int num_nodes = state.range(0);
+ while (state.KeepRunningBatch(num_nodes)) {
+ absl::synchronization_internal::GraphCycles g;
+ std::vector<absl::synchronization_internal::GraphId> nodes(num_nodes);
+ for (int i = 0; i < num_nodes; i++) {
+ nodes[i] = g.GetId(reinterpret_cast<void*>(static_cast<uintptr_t>(i)));
+ }
+ for (int i = 0; i < num_nodes; i++) {
+ int end = std::min(num_nodes, i + 5);
+ for (int j = i + 1; j < end; j++) {
+ ABSL_RAW_CHECK(g.InsertEdge(nodes[i], nodes[j]), "");
+ }
+ }
+ }
+}
+BENCHMARK(BM_StressTest)->Range(2048, 1048576);
+
+} // namespace
+
+BENCHMARK_MAIN();
diff --git a/absl/synchronization/mutex.cc b/absl/synchronization/mutex.cc
index bd54a4dc..e6525046 100644
--- a/absl/synchronization/mutex.cc
+++ b/absl/synchronization/mutex.cc
@@ -43,6 +43,7 @@
#include "absl/base/dynamic_annotations.h"
#include "absl/base/internal/atomic_hook.h"
#include "absl/base/internal/cycleclock.h"
+#include "absl/base/internal/hide_ptr.h"
#include "absl/base/internal/low_level_alloc.h"
#include "absl/base/internal/raw_logging.h"
#include "absl/base/internal/spinlock.h"
@@ -272,13 +273,6 @@ static absl::base_internal::SpinLock synch_event_mu(
// Can't be too small, as it's used for deadlock detection information.
static const uint32_t kNSynchEvent = 1031;
-// We need to hide Mutexes (or other deadlock detection's pointers)
-// from the leak detector.
-static const uintptr_t kHideMask = static_cast<uintptr_t>(0xF03A5F7BF03A5F7BLL);
-static uintptr_t MaskMu(const void *mu) {
- return reinterpret_cast<uintptr_t>(mu) ^ kHideMask;
-}
-
static struct SynchEvent { // this is a trivial hash table for the events
// struct is freed when refcount reaches 0
int refcount GUARDED_BY(synch_event_mu);
@@ -314,7 +308,8 @@ static SynchEvent *EnsureSynchEvent(std::atomic<intptr_t> *addr,
SynchEvent *e;
// first look for existing SynchEvent struct..
synch_event_mu.Lock();
- for (e = synch_event[h]; e != nullptr && e->masked_addr != MaskMu(addr);
+ for (e = synch_event[h];
+ e != nullptr && e->masked_addr != base_internal::HidePtr(addr);
e = e->next) {
}
if (e == nullptr) { // no SynchEvent struct found; make one.
@@ -325,7 +320,7 @@ static SynchEvent *EnsureSynchEvent(std::atomic<intptr_t> *addr,
e = reinterpret_cast<SynchEvent *>(
base_internal::LowLevelAlloc::Alloc(sizeof(*e) + l));
e->refcount = 2; // one for return value, one for linked list
- e->masked_addr = MaskMu(addr);
+ e->masked_addr = base_internal::HidePtr(addr);
e->invariant = nullptr;
e->arg = nullptr;
e->log = false;
@@ -367,7 +362,8 @@ static void ForgetSynchEvent(std::atomic<intptr_t> *addr, intptr_t bits,
SynchEvent *e;
synch_event_mu.Lock();
for (pe = &synch_event[h];
- (e = *pe) != nullptr && e->masked_addr != MaskMu(addr); pe = &e->next) {
+ (e = *pe) != nullptr && e->masked_addr != base_internal::HidePtr(addr);
+ pe = &e->next) {
}
bool del = false;
if (e != nullptr) {
@@ -388,7 +384,8 @@ static SynchEvent *GetSynchEvent(const void *addr) {
uint32_t h = reinterpret_cast<intptr_t>(addr) % kNSynchEvent;
SynchEvent *e;
synch_event_mu.Lock();
- for (e = synch_event[h]; e != nullptr && e->masked_addr != MaskMu(addr);
+ for (e = synch_event[h];
+ e != nullptr && e->masked_addr != base_internal::HidePtr(addr);
e = e->next) {
}
if (e != nullptr) {
diff --git a/absl/synchronization/mutex_benchmark.cc b/absl/synchronization/mutex_benchmark.cc
new file mode 100644
index 00000000..d91071b7
--- /dev/null
+++ b/absl/synchronization/mutex_benchmark.cc
@@ -0,0 +1,96 @@
+// Copyright 2017 The Abseil Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include <vector>
+
+#include "benchmark/benchmark.h"
+#include "absl/base/internal/sysinfo.h"
+#include "absl/synchronization/blocking_counter.h"
+#include "absl/synchronization/internal/thread_pool.h"
+#include "absl/synchronization/mutex.h"
+
+namespace {
+
+// Measure the overhead of conditions on mutex release (when they must be
+// evaluated). Mutex has (some) support for equivalence classes allowing
+// Conditions with the same function/argument to potentially not be multiply
+// evaluated.
+//
+// num_classes==0 is used for the special case of every waiter being distinct.
+void BM_ConditionWaiters(benchmark::State& state) {
+ int num_classes = state.range(0);
+ int num_waiters = state.range(1);
+
+ struct Helper {
+ static void Waiter(absl::BlockingCounter* init, absl::Mutex* m, int* p) {
+ init->DecrementCount();
+ m->LockWhen(absl::Condition(
+ static_cast<bool (*)(int*)>([](int* v) { return *v == 0; }), p));
+ m->Unlock();
+ }
+ };
+
+ if (num_classes == 0) {
+ // No equivalence classes.
+ num_classes = num_waiters;
+ }
+
+ absl::BlockingCounter init(num_waiters);
+ absl::Mutex mu;
+ std::vector<int> equivalence_classes(num_classes, 1);
+
+ // Must be declared last to be destroyed first.
+ absl::synchronization_internal::ThreadPool pool(num_waiters);
+
+ for (int i = 0; i < num_waiters; i++) {
+ // Mutex considers Conditions with the same function and argument
+ // to be equivalent.
+ pool.Schedule([&, i] {
+ Helper::Waiter(&init, &mu, &equivalence_classes[i % num_classes]);
+ });
+ }
+ init.Wait();
+
+ for (auto _ : state) {
+ mu.Lock();
+ mu.Unlock(); // Each unlock requires Condition evaluation for our waiters.
+ }
+
+ mu.Lock();
+ for (int i = 0; i < num_classes; i++) {
+ equivalence_classes[i] = 0;
+ }
+ mu.Unlock();
+}
+
+#ifdef THREAD_SANITIZER
+// ThreadSanitizer can't handle 8192 threads.
+constexpr int kMaxConditionWaiters = 2048;
+#else
+constexpr int kMaxConditionWaiters = 8192;
+#endif
+BENCHMARK(BM_ConditionWaiters)->RangePair(0, 2, 1, kMaxConditionWaiters);
+
+void BM_ContendedMutex(benchmark::State& state) {
+ static absl::Mutex* mu = new absl::Mutex;
+ for (auto _ : state) {
+ absl::MutexLock lock(mu);
+ }
+}
+BENCHMARK(BM_ContendedMutex)->Threads(1);
+BENCHMARK(BM_ContendedMutex)->ThreadPerCpu();
+
+} // namespace
+
+BENCHMARK_MAIN();
generated by cgit v1.2.3 (git 2.39.1) at 2024-12-27 07:40:20 +0000