Re: [PATCH] selftests/vm: 10x speedup for hmm-tests

From: John Hubbard
Date: Tue Oct 06 2020 - 16:34:43 EST


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@xxxxxxxxxx>
Signed-off-by: John Hubbard <jhubbard@xxxxxxxxxx>
---

Andrew, do you think we can get this one merged into mmotm? I think it's
pretty low risk.


thanks,
--
John Hubbard
NVIDIA


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)))