| Message ID | 20211211084928.410669-1-davidgow@google.com (mailing list archive) |
|---|---|
| State | New |
| Delegated to: | Brendan Higgins |
| Headers | show |
| Series | kunit: tool: Default --jobs to number of CPUs | expand |
On Sat, Dec 11, 2021 at 12:49 AM David Gow <davidgow@google.com> wrote: > > The --jobs parameter for kunit_tool currently defaults to 8 CPUs, > regardless of the number available. For systems with significantly more > (or less), this is not as efficient. Instead, default --jobs to the > number of CPUs present in the system: while there are as many > superstitions as to exactly what the ideal jobs:CPU ratio is, this seems > sufficiently sensible to me. > > Signed-off-by: David Gow <davidgow@google.com> Reminder: the unit tests depend on this hard-coded value. $ ag '\b8\b' tools/testing/kunit/kunit_tool_test.py 422: self.linux_source_mock.build_kernel.assert_called_once_with(False, 8, '.kunit', None) 529: self.linux_source_mock.build_kernel.assert_called_once_with(False, 8, build_dir, None) > --- > tools/testing/kunit/kunit.py | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/tools/testing/kunit/kunit.py b/tools/testing/kunit/kunit.py > index 68e6f461c758..2cb6c7db5683 100755 > --- a/tools/testing/kunit/kunit.py > +++ b/tools/testing/kunit/kunit.py > @@ -310,7 +310,7 @@ def add_build_opts(parser) -> None: > parser.add_argument('--jobs', > help='As in the make command, "Specifies the number of ' > 'jobs (commands) to run simultaneously."', > - type=int, default=8, metavar='jobs') > + type=int, default=os.cpu_count(), metavar='jobs') Just looking for edge cases: https://docs.python.org/3/library/os.html#os.cpu_count says > Returns None if undetermined and > This number is not equivalent to the number of CPUs the current process can use. The number of usable CPUs can be obtained with len(os.sched_getaffinity(0)) I assume the None caveat is mainly for other operating systems and doubt it'll impact any users. The second point is a bit more interesting, but still niche. Up to you if you want to use that instead. Super unscientific comparison (n=1) running all on CPU #0 $ taskset 0x1 ./tools/testing/kunit/kunit.py run --jobs=1 Elapsed time: ... 155.978s building ... --jobs=2 (some people swear by the 2x ratio) Elapsed time: ... 158.891s building ... --jobs=8 (Old behavior) ... Elapsed time: ... 171.448s building --jobs=32 Elapsed time: ... 170.765s building ... So the overhead of j being "too high" isn't that bad and it doesn't seem to matter much either way. > > def add_exec_opts(parser) -> None: > parser.add_argument('--timeout', > -- > 2.34.1.173.g76aa8bc2d0-goog >
On Sun, Dec 12, 2021 at 4:37 AM Daniel Latypov <dlatypov@google.com> wrote: > > On Sat, Dec 11, 2021 at 12:49 AM David Gow <davidgow@google.com> wrote: > > > > The --jobs parameter for kunit_tool currently defaults to 8 CPUs, > > regardless of the number available. For systems with significantly more > > (or less), this is not as efficient. Instead, default --jobs to the > > number of CPUs present in the system: while there are as many > > superstitions as to exactly what the ideal jobs:CPU ratio is, this seems > > sufficiently sensible to me. > > > > Signed-off-by: David Gow <davidgow@google.com> > > Reminder: the unit tests depend on this hard-coded value. > $ ag '\b8\b' tools/testing/kunit/kunit_tool_test.py > 422: > self.linux_source_mock.build_kernel.assert_called_once_with(False, 8, > '.kunit', None) > 529: > self.linux_source_mock.build_kernel.assert_called_once_with(False, 8, > build_dir, None) > Gah: that's what I get for rushing this through at the end of the day. v2 will have this no-longer hardcoded, but call a get_default_jobs() function which calculates the default. > > --- > > tools/testing/kunit/kunit.py | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/tools/testing/kunit/kunit.py b/tools/testing/kunit/kunit.py > > index 68e6f461c758..2cb6c7db5683 100755 > > --- a/tools/testing/kunit/kunit.py > > +++ b/tools/testing/kunit/kunit.py > > @@ -310,7 +310,7 @@ def add_build_opts(parser) -> None: > > parser.add_argument('--jobs', > > help='As in the make command, "Specifies the number of ' > > 'jobs (commands) to run simultaneously."', > > - type=int, default=8, metavar='jobs') > > + type=int, default=os.cpu_count(), metavar='jobs') > > Just looking for edge cases: > https://docs.python.org/3/library/os.html#os.cpu_count says > > Returns None if undetermined > and > > This number is not equivalent to the number of CPUs the current process can use. The number of usable CPUs can be obtained with len(os.sched_getaffinity(0)) > > I assume the None caveat is mainly for other operating systems and > doubt it'll impact any users. > The second point is a bit more interesting, but still niche. > Up to you if you want to use that instead. > > Super unscientific comparison (n=1) running all on CPU #0 > > $ taskset 0x1 ./tools/testing/kunit/kunit.py run --jobs=1 > Elapsed time: ... 155.978s building ... > > --jobs=2 (some people swear by the 2x ratio) > Elapsed time: ... 158.891s building ... > > --jobs=8 (Old behavior) > ... > Elapsed time: ... 171.448s building > > --jobs=32 > Elapsed time: ... 170.765s building ... > > So the overhead of j being "too high" isn't that bad and it doesn't > seem to matter much either way. > > I'll go with len(os.sched_getaffinity(0)) in v2: it is technically closer to what the intent is here, even if it's not a problem in general. Putting it in a helper function will make the len(os.sched_getaffinity(0)) call less unwieldy, IMHO, too. > > > > def add_exec_opts(parser) -> None: > > parser.add_argument('--timeout', > > -- > > 2.34.1.173.g76aa8bc2d0-goog > > Cheers, -- David
diff --git a/tools/testing/kunit/kunit.py b/tools/testing/kunit/kunit.py index 68e6f461c758..2cb6c7db5683 100755 --- a/tools/testing/kunit/kunit.py +++ b/tools/testing/kunit/kunit.py @@ -310,7 +310,7 @@ def add_build_opts(parser) -> None: parser.add_argument('--jobs', help='As in the make command, "Specifies the number of ' 'jobs (commands) to run simultaneously."', - type=int, default=8, metavar='jobs') + type=int, default=os.cpu_count(), metavar='jobs') def add_exec_opts(parser) -> None: parser.add_argument('--timeout',
The --jobs parameter for kunit_tool currently defaults to 8 CPUs, regardless of the number available. For systems with significantly more (or less), this is not as efficient. Instead, default --jobs to the number of CPUs present in the system: while there are as many superstitions as to exactly what the ideal jobs:CPU ratio is, this seems sufficiently sensible to me. Signed-off-by: David Gow <davidgow@google.com> --- tools/testing/kunit/kunit.py | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)