hazptr: Add microbenchmark for unused tagged obj batch

Summary:
Adds a microbenchmark for the lifetime of an unused tagged hazptr_obj_batch in the presence of unrelated objects in the domain's tagged list.

This diff also makes the calculation of the number of operations and the scalability measure for the cleanup microbenchmark more consistent with those for the other microbenchmarks.

Reviewed By: davidtgoldblatt

Differential Revision: D17416088

fbshipit-source-id: b59fd1b48114d591da5d9432df7910d940683006

folly/synchronization/test/HazptrTest.cpp

@@ -1404,7 +1404,7 @@ uint64_t cleanup_bench(std::string name, int nthreads) {
     auto init = [] {};
     auto fn = [&](int) {
       hazptr_holder<std::atomic> hptr;
-      for (int i = 0; i < 1000; i++) {
+      for (int i = 0; i < ops / 1000; i++) {
         hazptr_cleanup();
       }
     };
@@ -1414,6 +1414,30 @@ uint64_t cleanup_bench(std::string name, int nthreads) {
   return bench(name, ops, repFn);
 }
 
+uint64_t batch_bench(std::string name, int nthreads) {
+  struct Foo : public hazptr_obj_base<Foo> {};
+  // Push unrelated objects into the domain tagged list
+  hazptr_obj_batch batch;
+  for (int i = 0; i < 999; ++i) {
+    auto p = new Foo;
+    p->set_batch_tag(&batch);
+    p->retire();
+  }
+  auto repFn = [&] {
+    auto init = [] {};
+    auto fn = [&](int tid) {
+      for (int j = tid; j < ops; j += nthreads) {
+        hazptr_obj_batch b;
+        b.shutdown_and_reclaim();
+        hazptr_cleanup_batch_tag<std::atomic>(&b);
+      }
+    };
+    auto endFn = [] {};
+    return run_once(nthreads, init, fn, endFn);
+  };
+  return bench(name, ops, repFn);
+}
+
 const int nthr[] = {1, 10};
 const int sizes[] = {10, 20};
 
@@ -1448,8 +1472,10 @@ void benches() {
       std::cout << j << "-item list protect all                      ";
       list_protect_all_bench("", i, j);
     }
-    std::cout << "hazptr_cleanup                                ";
+    std::cout << "1/1000 hazptr_cleanup                         ";
     cleanup_bench("", i);
+    std::cout << "Life cycle of unused tagged obj batch         ";
+    batch_bench("", i);
   }
 }
 
@@ -1479,7 +1505,8 @@ allocate/retire/reclaim object                     70 ns     68 ns     67 ns
 20-item list hand-over-hand                        48 ns     43 ns     41 ns
 20-item list protect all - own hazptr              28 ns     28 ns     28 ns
 20-item list protect all                           31 ns     29 ns     29 ns
-hazptr_cleanup                                      2 ns      1 ns      1 ns
+1/1000 hazptr_cleanup                               2 ns      1 ns      1 ns
+Life cycle of unused tagged obj batch            1577 ns   1547 ns   1511 ns
 ================================ 10 threads ================================
 10x construct/destruct hazptr_holder               11 ns      8 ns      8 ns
 10x construct/destruct hazptr_array<1>              8 ns      7 ns      7 ns
@@ -1497,5 +1524,6 @@ allocate/retire/reclaim object                     20 ns     17 ns     16 ns
 20-item list hand-over-hand                         6 ns      6 ns      6 ns
 20-item list protect all - own hazptr               4 ns      4 ns      4 ns
 20-item list protect all                            5 ns      4 ns      4 ns
-hazptr_cleanup                                    119 ns    113 ns     97 ns
- */
+1/1000 hazptr_cleanup                             119 ns    113 ns     97 ns
+Life cycle of unused tagged obj batch            1985 ns   1918 ns   1853 ns
+*/