Support memory alignment tests for string_benchmark.cpp
Test: Manually verify that benchmark times are similar and add a unit test.
Change-Id: Idaaeb4c8c3629f797ffd8d0c86c8d7b7b9653181
diff --git a/benchmarks/util.cpp b/benchmarks/util.cpp
new file mode 100644
index 0000000..31d7e04
--- /dev/null
+++ b/benchmarks/util.cpp
@@ -0,0 +1,92 @@
+/*
+ * Copyright (C) 2017 The Android Open Source Project
+ *
+ * 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 "util.h"
+
+#include <sched.h>
+#include <stdio.h>
+#include <string.h>
+#include <cstdlib>
+#include <vector>
+
+// This function returns a pointer less than 2 * alignment + or_mask bytes into the array.
+char *GetAlignedMemory(char *orig_ptr, size_t alignment, size_t or_mask) {
+ if ((alignment & (alignment - 1)) != 0) {
+ fprintf(stderr, "warning: alignment passed into GetAlignedMemory is not a power of two.\n");
+ std::abort();
+ }
+ if (or_mask > alignment) {
+ fprintf(stderr, "warning: or_mask passed into GetAlignedMemory is too high.\n");
+ std::abort();
+ }
+ uintptr_t ptr = reinterpret_cast<uintptr_t>(orig_ptr);
+ if (alignment > 0) {
+ // When setting the alignment, set it to exactly the alignment chosen.
+ // The pointer returned will be guaranteed not to be aligned to anything
+ // more than that.
+ ptr += alignment - (ptr & (alignment - 1));
+ ptr |= alignment | or_mask;
+ }
+
+ return reinterpret_cast<char*>(ptr);
+}
+
+char *GetAlignedPtr(std::vector<char>* buf, size_t alignment, size_t nbytes) {
+ buf->resize(nbytes + 3 * alignment);
+ return GetAlignedMemory(buf->data(), alignment, 0);
+}
+
+char *GetAlignedPtrFilled(std::vector<char>* buf, size_t alignment, size_t nbytes, char fill_byte) {
+ char* buf_aligned = GetAlignedPtr(buf, alignment, nbytes);
+ memset(buf_aligned, fill_byte, nbytes);
+ return buf_aligned;
+}
+
+bool LockToCPU(int cpu_to_lock) {
+ cpu_set_t cpuset;
+
+ CPU_ZERO(&cpuset);
+ if (sched_getaffinity(0, sizeof(cpuset), &cpuset) != 0) {
+ perror("sched_getaffinity failed");
+ return false;
+ }
+
+ if (cpu_to_lock < 0) {
+ // Lock to the last active core we find.
+ for (int i = 0; i < CPU_SETSIZE; i++) {
+ if (CPU_ISSET(i, &cpuset)) {
+ cpu_to_lock = i;
+ }
+ }
+ } else if (!CPU_ISSET(cpu_to_lock, &cpuset)) {
+ printf("Cpu %d does not exist.\n", cpu_to_lock);
+ return false;
+ }
+
+ if (cpu_to_lock < 0) {
+ printf("Cannot find any valid cpu to lock.\n");
+ return false;
+ }
+
+ CPU_ZERO(&cpuset);
+ CPU_SET(cpu_to_lock, &cpuset);
+ if (sched_setaffinity(0, sizeof(cpuset), &cpuset) != 0) {
+ perror("sched_setaffinity failed");
+ return false;
+ }
+
+ return true;
+}