Optimize Memory::ReadString
This function is responsible for majority of CPU time in prefetto.
Reduce the number of memory reads (don't read strings byte-by-byte).
Update all calls of ReadString to include the third parameter to have
a max read.
Add an Elf creation benchmark since this function is on the elf
creation path.
Test: libunwindstack_unit_test
Change-Id: Ia36e1f1a5ba76c9e9f13c43fb9e3691dde7897f2
diff --git a/libunwindstack/benchmarks/ElfBenchmark.cpp b/libunwindstack/benchmarks/ElfBenchmark.cpp
new file mode 100644
index 0000000..c108a2a
--- /dev/null
+++ b/libunwindstack/benchmarks/ElfBenchmark.cpp
@@ -0,0 +1,77 @@
+/*
+ * Copyright (C) 2020 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 <err.h>
+#include <malloc.h>
+#include <stdint.h>
+
+#include <string>
+
+#include <benchmark/benchmark.h>
+
+#include <unwindstack/Elf.h>
+#include <unwindstack/Memory.h>
+
+#include "Utils.h"
+
+static void BenchmarkElfCreate(benchmark::State& state, const std::string& elf_file) {
+#if defined(__BIONIC__)
+ uint64_t rss_bytes = 0;
+#endif
+ uint64_t alloc_bytes = 0;
+ for (auto _ : state) {
+ state.PauseTiming();
+#if defined(__BIONIC__)
+ mallopt(M_PURGE, 0);
+ uint64_t rss_bytes_before = 0;
+ GatherRss(&rss_bytes_before);
+#endif
+ uint64_t alloc_bytes_before = mallinfo().uordblks;
+ auto file_memory = unwindstack::Memory::CreateFileMemory(elf_file, 0);
+ state.ResumeTiming();
+
+ unwindstack::Elf elf(file_memory.release());
+ if (!elf.Init() || !elf.valid()) {
+ errx(1, "Internal Error: Cannot open elf.");
+ }
+
+ state.PauseTiming();
+#if defined(__BIONIC__)
+ mallopt(M_PURGE, 0);
+#endif
+ alloc_bytes += mallinfo().uordblks - alloc_bytes_before;
+#if defined(__BIONIC__)
+ GatherRss(&rss_bytes);
+ rss_bytes -= rss_bytes_before;
+#endif
+ state.ResumeTiming();
+ }
+
+#if defined(__BIONIC__)
+ state.counters["RSS_BYTES"] = rss_bytes / static_cast<double>(state.iterations());
+#endif
+ state.counters["ALLOCATED_BYTES"] = alloc_bytes / static_cast<double>(state.iterations());
+}
+
+void BM_elf_create(benchmark::State& state) {
+ BenchmarkElfCreate(state, GetElfFile());
+}
+BENCHMARK(BM_elf_create);
+
+void BM_elf_create_compressed(benchmark::State& state) {
+ BenchmarkElfCreate(state, GetCompressedElfFile());
+}
+BENCHMARK(BM_elf_create_compressed);