Overhead of using shell=True is quite significant.
Micro-benchmark of running ethtool --help shows that
non-shell run is 2x faster.
Runtime of the XDP tests also shows improvement:
this patch: 2m34s 2m21s 2m18s 2m18s
before: 2m54s 2m36s 2m34s
Signed-off-by: Jakub Kicinski <[email protected]>
---
tools/testing/selftests/net/lib/py/utils.py | 11 +++++++++--
1 file changed, 9 insertions(+), 2 deletions(-)
diff --git a/tools/testing/selftests/net/lib/py/utils.py
b/tools/testing/selftests/net/lib/py/utils.py
index b188cac49738..e7155b6db9a3 100644
--- a/tools/testing/selftests/net/lib/py/utils.py
+++ b/tools/testing/selftests/net/lib/py/utils.py
@@ -29,9 +29,12 @@ import time
"""
Execute a command on local or remote host.
+ @shell defaults to false, and class will try to split @comm into a list
+ if it's a string with spaces.
+
Use bkg() instead to run a command in the background.
"""
- def __init__(self, comm, shell=True, fail=True, ns=None, background=False,
+ def __init__(self, comm, shell=None, fail=True, ns=None, background=False,
host=None, timeout=5, ksft_wait=None):
if ns:
comm = f'ip netns exec {ns} ' + comm
@@ -45,6 +48,10 @@ import time
if host:
self.proc = host.cmd(comm)
else:
+ # If user doesn't explicitly request shell try to avoid it.
+ if shell is None and isinstance(comm, str) and ' ' in comm:
+ comm = comm.split()
+
# ksft_wait lets us wait for the background process to fully start,
# we pass an FD to the child process, and wait for it to write
back.
# Similarly term_fd tells child it's time to exit.
@@ -111,7 +118,7 @@ import time
with bkg("my_binary", ksft_wait=5):
"""
- def __init__(self, comm, shell=True, fail=None, ns=None, host=None,
+ def __init__(self, comm, shell=None, fail=None, ns=None, host=None,
exit_wait=False, ksft_wait=None):
super().__init__(comm, background=True,
shell=shell, fail=fail, ns=ns, host=host,
--
2.51.0
