use zeros for benchmarks

src/borg/archiver.py

@@ -453,9 +453,10 @@ def measurement_run(repo, path):
         def test_files(path, count, size, random):
             path = os.path.join(path, 'borg-test-data')
             os.makedirs(path)
+            z_buff = None if random else memoryview(zeros)[:size] if size <= len(zeros) else b'\0' * size
             for i in range(count):
                 fname = os.path.join(path, 'file_%d' % i)
-                data = b'\0' * size if not random else os.urandom(size)
+                data = z_buff if not random else os.urandom(size)
                 with SyncFile(fname, binary=True) as fd:  # used for posix_fadvise's sake
                     fd.write(data)
             yield path

src/borg/testsuite/benchmark.py

@@ -11,6 +11,7 @@
 import pytest
 
 from .archiver import changedir, cmd
+from ..constants import zeros
 
 
 @pytest.fixture
@@ -34,12 +35,13 @@ def repo(request, cmd, repo_url):
 @pytest.fixture(scope='session', params=["zeros", "random"])
 def testdata(request, tmpdir_factory):
     count, size = 10, 1000*1000
+    assert size <= len(zeros)
     p = tmpdir_factory.mktemp('data')
     data_type = request.param
     if data_type == 'zeros':
         # do not use a binary zero (\0) to avoid sparse detection
         def data(size):
-            return b'0' * size
+            return memoryview(zeros)[:size]
     elif data_type == 'random':
         def data(size):
             return os.urandom(size)