Initial commit

5 files changed, 162 insertions, 0 deletions

diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..407b5f9
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,2 @@
+arena-malloc
+arena-memstream
diff --git a/Makefile b/Makefile
new file mode 100644
index 0000000..55248ea
--- /dev/null
+++ b/Makefile
@@ -0,0 +1,4 @@
+#CFLAGS=-fsanitize=address,undefined -g3
+CFLAGS=-Ofast
+
+all: arena-malloc arena-memstream
diff --git a/Readme.md b/Readme.md
new file mode 100644
index 0000000..67d3dc5
--- /dev/null
+++ b/Readme.md
@@ -0,0 +1,40 @@
+# Arena allocator benchmark
+
+`50_000_000` of 16 byte allocations, `-Ofast`, without sanitizers.
+
+arena-malloc (`realloc` 1.5x of size):
+
+```
+$ perf stat -r10 -B ./arena-malloc
+
+ Performance counter stats for './arena-malloc' (10 runs):
+
+            340.31 msec task-clock:u                     #    0.965 CPUs utilized               ( +-  0.77% )
+                 0      context-switches:u               #    0.000 /sec
+                 0      cpu-migrations:u                 #    0.000 /sec
+             6,055      page-faults:u                    #   17.792 K/sec                       ( +-  0.01% )
+       255,422,997      cycles:u                         #    0.751 GHz                         ( +-  0.07% )
+       700,131,646      instructions:u                   #    2.74  insn per cycle              ( +-  0.00% )
+       100,031,363      branches:u                       #  293.938 M/sec                       ( +-  0.00% )
+             2,612      branch-misses:u                  #    0.00% of all branches             ( +-  0.97% )
+
+           0.35257 +- 0.00692 seconds time elapsed  ( +-  1.96% )
+```
+
+arena-memstream (`open_memstream`, `fwrite`, `fflush`):
+```
+$ perf stat -r10 -B ./arena-memstream
+
+ Performance counter stats for './arena-memstream' (10 runs):
+
+          3,914.75 msec task-clock:u                     #    0.978 CPUs utilized               ( +-  0.07% )
+                 0      context-switches:u               #    0.000 /sec
+                 0      cpu-migrations:u                 #    0.000 /sec
+            46,927      page-faults:u                    #   11.987 K/sec                       ( +-  0.39% )
+     8,395,773,261      cycles:u                         #    2.145 GHz                         ( +-  0.07% )
+    14,089,659,266      instructions:u                   #    1.68  insn per cycle              ( +-  0.00% )
+     2,871,455,062      branches:u                       #  733.496 M/sec                       ( +-  0.00% )
+           447,933      branch-misses:u                  #    0.02% of all branches             ( +- 47.49% )
+
+           4.00461 +- 0.00335 seconds time elapsed  ( +-  0.08% )
+```
diff --git a/arena-malloc.c b/arena-malloc.c
new file mode 100644
index 0000000..4246047
--- /dev/null
+++ b/arena-malloc.c
@@ -0,0 +1,61 @@
+#include <assert.h>
+#include <stdio.h>
+#include <stddef.h>
+#include <string.h>
+#include <stdlib.h>
+#include <stdint.h>
+
+struct arena {
+    void *buffer;
+    size_t offset;
+    size_t size;
+};
+
+void arena_create(struct arena *arena)
+{
+    unsigned long const init_size = 10ul * 1024ul * 1024ul;
+    *arena = (struct arena){
+        .buffer = malloc(init_size),
+        .size = init_size,
+    };
+}
+
+void arena_destroy(struct arena *arena)
+{
+    free(arena->buffer);
+    *arena = (struct arena){0};
+}
+
+size_t arena_add(struct arena *arena, void const *data, size_t const size)
+{
+    size_t const offset = arena->offset;
+    if (size + offset > arena->size) {
+        arena->size = (size + offset) * 1.5;
+        arena->buffer = realloc(arena->buffer, arena->size);
+        assert(arena->buffer);
+    }
+    if (data) {
+        memcpy(arena->buffer + offset, data, size);
+    }
+    arena->offset += size;
+    return offset;
+}
+
+static inline void *arena_get(struct arena const *arena, size_t offset)
+{
+    return arena->buffer + offset;
+}
+
+int main(int argc, char * const argv[])
+{
+    (void)argc;
+    (void)argv;
+    struct arena arena;
+    arena_create(&arena);
+    unsigned data[4] = {1u, 2u, 3u, 4u};
+    for (size_t i = 0; i < 50000000lu; i++) {
+        size_t const offset = arena_add(&arena, data, sizeof(data));
+        data[0] = (uintptr_t)arena_get(&arena, offset);
+    }
+    arena_destroy(&arena);
+}
diff --git a/arena-memstream.c b/arena-memstream.c
new file mode 100644
index 0000000..64ca090
--- /dev/null
+++ b/arena-memstream.c
@@ -0,0 +1,55 @@
+#include <assert.h>
+#include <stdio.h>
+#include <stddef.h>
+#include <string.h>
+#include <stdlib.h>
+#include <stdint.h>
+
+struct arena {
+    FILE *stream;
+    char *buffer;
+    size_t offset;
+    size_t size;
+};
+
+void arena_create(struct arena *arena)
+{
+    *arena = (struct arena){open_memstream(&arena->buffer, &arena->size)};
+}
+
+void arena_destroy(struct arena *arena)
+{
+    fclose(arena->stream);
+    free(arena->buffer);
+    *arena = (struct arena){0};
+}
+
+size_t arena_add(struct arena *arena, void const *data, size_t const size)
+{
+    size_t const offset = arena->offset;
+    if (data) {
+        fwrite(data, 1, size, arena->stream);
+    }
+    arena->offset += size;
+    return offset;
+}
+
+static inline void *arena_get(struct arena const *arena, size_t offset)
+{
+    fflush(arena->stream);
+    return arena->buffer + offset;
+}
+
+int main(int argc, char * const argv[])
+{
+    (void)argc;
+    (void)argv;
+    struct arena arena;
+    arena_create(&arena);
+    unsigned data[4] = {1u, 2u, 3u, 4u};
+    for (size_t i = 0; i < 50000000lu; i++) {
+        size_t const offset = arena_add(&arena, data, sizeof(data));
+        data[0] = (uintptr_t)arena_get(&arena, offset);
+    }
+    arena_destroy(&arena);
+}