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

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Message-ID: <20201003011721.44238-1-jhubbard@nvidia.com>
Date:   Fri, 2 Oct 2020 18:17:21 -0700
From:   John Hubbard <jhubbard@...dia.com>
To:     Andrew Morton <akpm@...ux-foundation.org>
CC:     Shuah Khan <shuah@...nel.org>, LKML <linux-kernel@...r.kernel.org>,
        <linux-mm@...ck.org>, <linux-kselftest@...r.kernel.org>,
        John Hubbard <jhubbard@...dia.com>,
        Ralph Campbell <rcampbell@...dia.com>
Subject: [PATCH] selftests/vm: 10x speedup for hmm-tests

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@...dia.com>
Signed-off-by: John Hubbard <jhubbard@...dia.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