Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
From:   John Hubbard <jhubbard@nvidia.com>
To:     Andrew Morton <akpm@linux-foundation.org>
CC:     Shuah Khan <shuah@kernel.org>, LKML <linux-kernel@vger.kernel.org>,
        <linux-mm@kvack.org>, <linux-kselftest@vger.kernel.org>,
        John Hubbard <jhubbard@nvidia.com>
Subject: [PATCH 1/1] selftests/vm: 8x compaction_test speedup
Date:   Fri, 2 Oct 2020 01:06:21 -0700
Message-ID: <20201002080621.551044-2-jhubbard@nvidia.com>
In-Reply-To: <20201002080621.551044-1-jhubbard@nvidia.com>
References: <20201002080621.551044-1-jhubbard@nvidia.com>
MIME-Version: 1.0
Content-Transfer-Encoding: quoted-printable
Content-Type: text/plain
Precedence: bulk

This patch reduces the running time for compaction_test from about 27
sec, to 3.3 sec, which is about an 8x speedup.

These numbers are for an Intel x86_64 system with 32 GB of DRAM.

The compaction_test.c program was spending most of its time doing
mmap(), 1 MB at a time, on about 25 GB of memory.

Instead, do the mmaps 100 MB at a time. (Going past 100 MB doesn't make
things go much faster, because other parts of the program are using the
remaining time.)

Signed-off-by: John Hubbard <jhubbard@nvidia.com>
---
 tools/testing/selftests/vm/compaction_test.c | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/tools/testing/selftests/vm/compaction_test.c b/tools/testing/s=
elftests/vm/compaction_test.c
index bcec71250873..9b420140ba2b 100644
--- a/tools/testing/selftests/vm/compaction_test.c
+++ b/tools/testing/selftests/vm/compaction_test.c
@@ -18,7 +18,8 @@
=20
 #include "../kselftest.h"
=20
-#define MAP_SIZE 1048576
+#define MAP_SIZE_MB	100
+#define MAP_SIZE	(MAP_SIZE_MB * 1024 * 1024)
=20
 struct map_list {
 	void *map;
@@ -165,7 +166,7 @@ int main(int argc, char **argv)
 	void *map =3D NULL;
 	unsigned long mem_free =3D 0;
 	unsigned long hugepage_size =3D 0;
-	unsigned long mem_fragmentable =3D 0;
+	long mem_fragmentable_MB =3D 0;
=20
 	if (prereq() !=3D 0) {
 		printf("Either the sysctl compact_unevictable_allowed is not\n"
@@ -190,9 +191,9 @@ int main(int argc, char **argv)
 		return -1;
 	}
=20
-	mem_fragmentable =3D mem_free * 0.8 / 1024;
+	mem_fragmentable_MB =3D mem_free * 0.8 / 1024;
=20
-	while (mem_fragmentable > 0) {
+	while (mem_fragmentable_MB > 0) {
 		map =3D mmap(NULL, MAP_SIZE, PROT_READ | PROT_WRITE,
 			   MAP_ANONYMOUS | MAP_PRIVATE | MAP_LOCKED, -1, 0);
 		if (map =3D=3D MAP_FAILED)
@@ -213,7 +214,7 @@ int main(int argc, char **argv)
 		for (i =3D 0; i < MAP_SIZE; i +=3D page_size)
 			*(unsigned long *)(map + i) =3D (unsigned long)map + i;
=20
-		mem_fragmentable--;
+		mem_fragmentable_MB -=3D MAP_SIZE_MB;
 	}
=20
 	for (entry =3D list; entry !=3D NULL; entry =3D entry->next) {
--=20
2.28.0