Add simple memory allocation benchmark

doc/benchmarks.rst

@@ -53,6 +53,18 @@ depending on the Python version.
    Files are called ``.py.txt`` instead of ``.py`` to not run PEP 8 checks on
    them, and more generally to not modify them.
 
+alloc
+-----
+
+Allocate blocks of memory with ``bytesarray``. The default sizes are smaller or
+equal to obmalloc's small request threshold.
+
+Command lines options::
+
+  sizes                 Block sizes (default: 4 8 16 32 64 128 256 446)
+
+  --repeat REPEAT       Repeat allocations (default: 100)
+
 
 chameleon
 ---------

pyperformance/data-files/benchmarks/MANIFEST

@@ -2,6 +2,7 @@
 
 name	metafile
 2to3	<local>
+alloc	<local>
 chameleon	<local>
 chaos	<local>
 crypto_pyaes	<local>

pyperformance/data-files/benchmarks/bm_alloc/pyproject.toml

@@ -0,0 +1,9 @@
+[project]
+name = "pyperformance_bm_alloc"
+requires-python = ">=3.8"
+dependencies = ["pyperf"]
+urls = {repository = "https://github.com/python/pyperformance"}
+dynamic = ["version"]
+
+[tool.pyperformance]
+name = "alloc"

pyperformance/data-files/benchmarks/bm_alloc/run_benchmark.py

@@ -0,0 +1,73 @@
+# coding: utf-8
+"""
+Allocate blocks of memory with bytearray
+
+This benchmark stresses the memory allocator. Default sizes are <=
+obmalloc's small request threshold.
+"""
+
+import sys
+
+import pyperf
+
+# see Objects/obmalloc.c
+SMALL_REQUEST_THRESHOLD = 512
+APPEND_SIZE = 10
+SIZEOF_BYTEARRAY = sys.getsizeof(bytearray())
+
+REPEAT_ALLOCS = 100
+
+DEFAULT_SIZES = [
+    4,
+    8,
+    16,
+    32,
+    64,
+    128,
+    256,
+    # keep below obmalloc threshold
+    SMALL_REQUEST_THRESHOLD - SIZEOF_BYTEARRAY - APPEND_SIZE,
+]
+
+
+def allocate(repeat, sizes, alloc_func=bytearray):
+    append = alloc_func(APPEND_SIZE)
+    for size in sizes:
+        append = alloc_func(size)
+        for i in range(repeat):
+            # malloc()
+            block = alloc_func(size)
+            # realloc()
+            block += append
+        # free()
+        del block
+
+
+def add_cmdline_args(cmd, args):
+    cmd.extend(("--repeat", str(args.repeat)))
+    cmd.extend(tuple(str(s) for s in args.sizes))
+
+
+if __name__ == "__main__":
+    runner = pyperf.Runner(add_cmdline_args=add_cmdline_args)
+
+    cmd = runner.argparser
+    cmd.add_argument(
+        "--repeat",
+        type=int,
+        default=REPEAT_ALLOCS,
+        help=f"Repeat allocations (default: {REPEAT_ALLOCS})",
+    )
+    cmd.add_argument(
+        "sizes",
+        type=int,
+        nargs="*",
+        default=DEFAULT_SIZES,
+        help=f"Block sizes (default: {' '.join(str(s) for s in DEFAULT_SIZES)})",
+    )
+
+    args = runner.parse_args()
+    runner.metadata["description"] = "Allocate blocks of memory."
+    runner.metadata["alloc_repeat"] = args.repeat
+    runner.metadata["alloc_sizes"] = ",".join(str(s) for s in args.sizes)
+    runner.bench_func("alloc", allocate, args.repeat, args.sizes)