This patch reduces the running time for hmm-tests from about 10+ seconds, to just under 1.0 second, for an approximately 10x speedup. That brings it in line with most of the other tests in selftests/vm, which mostly run in < 1 sec.
This is done with a one-line change that simply reduces the number of iterations of several tests, from 256, to 10. Thanks to Ralph Campbell for suggesting changing NTIMES as a way to get the speedup.
Suggested-by: Ralph Campbell rcampbell@nvidia.com Signed-off-by: John Hubbard jhubbard@nvidia.com ---
This is based on mmotm.
tools/testing/selftests/vm/hmm-tests.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/tools/testing/selftests/vm/hmm-tests.c b/tools/testing/selftests/vm/hmm-tests.c index 6b79723d7dc6..5d1ac691b9f4 100644 --- a/tools/testing/selftests/vm/hmm-tests.c +++ b/tools/testing/selftests/vm/hmm-tests.c @@ -49,7 +49,7 @@ struct hmm_buffer { #define TWOMEG (1 << 21) #define HMM_BUFFER_SIZE (1024 << 12) #define HMM_PATH_MAX 64 -#define NTIMES 256 +#define NTIMES 10
#define ALIGN(x, a) (((x) + (a - 1)) & (~((a) - 1)))
On Fri, 2 Oct 2020 18:17:21 -0700 John Hubbard jhubbard@nvidia.com wrote:
This patch reduces the running time for hmm-tests from about 10+ seconds, to just under 1.0 second, for an approximately 10x speedup. That brings it in line with most of the other tests in selftests/vm, which mostly run in < 1 sec.
This is done with a one-line change that simply reduces the number of iterations of several tests, from 256, to 10.
Could this result in reduced test capacity? If so, how about making the number easily tweakable?
Thanks, SeongJae Park
Thanks to Ralph Campbell for suggesting changing NTIMES as a way to get the speedup.
Suggested-by: Ralph Campbell rcampbell@nvidia.com Signed-off-by: John Hubbard jhubbard@nvidia.com
This is based on mmotm.
tools/testing/selftests/vm/hmm-tests.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/tools/testing/selftests/vm/hmm-tests.c b/tools/testing/selftests/vm/hmm-tests.c index 6b79723d7dc6..5d1ac691b9f4 100644 --- a/tools/testing/selftests/vm/hmm-tests.c +++ b/tools/testing/selftests/vm/hmm-tests.c @@ -49,7 +49,7 @@ struct hmm_buffer { #define TWOMEG (1 << 21) #define HMM_BUFFER_SIZE (1024 << 12) #define HMM_PATH_MAX 64 -#define NTIMES 256 +#define NTIMES 10 #define ALIGN(x, a) (((x) + (a - 1)) & (~((a) - 1))) -- 2.28.0
On 10/2/20 10:23 PM, SeongJae Park wrote:
On Fri, 2 Oct 2020 18:17:21 -0700 John Hubbard jhubbard@nvidia.com wrote:
This patch reduces the running time for hmm-tests from about 10+ seconds, to just under 1.0 second, for an approximately 10x speedup. That brings it in line with most of the other tests in selftests/vm, which mostly run in < 1 sec.
This is done with a one-line change that simply reduces the number of iterations of several tests, from 256, to 10.
Could this result in reduced test capacity? If so, how about making the number easily tweakable?
The choice of iterations was somewhat arbitrary. Unless and until we have specific bugs that show up at a given number of iterations, we should avoid running large iteration counts that blow the testing time budget. Here, I'm not aware of any bugs that show up between 11 and 256 iterations, which is why I think 10 is an acceptable iteration count.
But, you are right: it's a nice thought to make the iteration count adjustable via the command line. That would allow hmm-tests to act as a quick selftest item, and also to provide a little bit more of a stress test, when manually invoked with a higher iteration count.
That's a separate patch, though. Because TEST_F() and related unit test macros used in this area, expect to run the same way every time, and they don't really want to be fed iteration arguments. Or maybe they do, and I've missed it on my first quick pass through.
And in fact, maybe it's not a good fit, if TEST_F() and kselftest are pushing for more of a CUnit/gtest style of coding.
There are some design and policy questions there. It reminds me that some programs here don't use TEST_F() at all, actually. But anyway, I'd definitely like to sidestep all of that for now, and start with just "get the test run time down under 1 second".
thanks, -- John Hubbard NVIDIA
On 10/2/20 6:17 PM, John Hubbard wrote:
This patch reduces the running time for hmm-tests from about 10+ seconds, to just under 1.0 second, for an approximately 10x speedup. That brings it in line with most of the other tests in selftests/vm, which mostly run in < 1 sec.
This is done with a one-line change that simply reduces the number of iterations of several tests, from 256, to 10. Thanks to Ralph Campbell for suggesting changing NTIMES as a way to get the speedup.
Suggested-by: Ralph Campbell rcampbell@nvidia.com Signed-off-by: John Hubbard jhubbard@nvidia.com
Andrew, do you think we can get this one merged into mmotm? I think it's pretty low risk.
thanks,
linux-kselftest-mirror@lists.linaro.org
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SeongJae Park