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From:   Keith Busch <keith.busch@intel.com>
To:     linux-mm@kvack.org, linux-kernel@vger.kernel.org
Cc:     Kirill Shutemov <kirill.shutemov@linux.intel.com>,
        Dave Hansen <dave.hansen@intel.com>,
        Dan Williams <dan.j.williams@intel.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Keith Busch <keith.busch@intel.com>
Subject: [PATCH 1/6] mm/gup_benchmark: Time put_page
Date:   Wed, 10 Oct 2018 13:56:00 -0600
Message-Id: <20181010195605.10689-1-keith.busch@intel.com>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

We'd like to measure time to unpin user pages, so this adds a second
benchmark timer on put_page, separate from get_page.

Adding the field will breaks this ioctl ABI, but should be okay since
this an in-tree kernel selftest.

Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Keith Busch <keith.busch@intel.com>
---
 mm/gup_benchmark.c                         | 8 ++++++--
 tools/testing/selftests/vm/gup_benchmark.c | 6 ++++--
 2 files changed, 10 insertions(+), 4 deletions(-)

diff --git a/mm/gup_benchmark.c b/mm/gup_benchmark.c
index 7405c9d89d65..b344abd6e8e4 100644
--- a/mm/gup_benchmark.c
+++ b/mm/gup_benchmark.c
@@ -8,7 +8,8 @@
 #define GUP_FAST_BENCHMARK	_IOWR('g', 1, struct gup_benchmark)
 
 struct gup_benchmark {
-	__u64 delta_usec;
+	__u64 get_delta_usec;
+	__u64 put_delta_usec;
 	__u64 addr;
 	__u64 size;
 	__u32 nr_pages_per_call;
@@ -48,14 +49,17 @@ static int __gup_benchmark_ioctl(unsigned int cmd,
 	}
 	end_time = ktime_get();
 
-	gup->delta_usec = ktime_us_delta(end_time, start_time);
+	gup->get_delta_usec = ktime_us_delta(end_time, start_time);
 	gup->size = addr - gup->addr;
 
+	start_time = ktime_get();
 	for (i = 0; i < nr_pages; i++) {
 		if (!pages[i])
 			break;
 		put_page(pages[i]);
 	}
+	end_time = ktime_get();
+	gup->put_delta_usec = ktime_us_delta(end_time, start_time);
 
 	kvfree(pages);
 	return 0;
diff --git a/tools/testing/selftests/vm/gup_benchmark.c b/tools/testing/selftests/vm/gup_benchmark.c
index 36df55132036..bdcb97acd0ac 100644
--- a/tools/testing/selftests/vm/gup_benchmark.c
+++ b/tools/testing/selftests/vm/gup_benchmark.c
@@ -17,7 +17,8 @@
 #define GUP_FAST_BENCHMARK	_IOWR('g', 1, struct gup_benchmark)
 
 struct gup_benchmark {
-	__u64 delta_usec;
+	__u64 get_delta_usec;
+	__u64 put_delta_usec;
 	__u64 addr;
 	__u64 size;
 	__u32 nr_pages_per_call;
@@ -81,7 +82,8 @@ int main(int argc, char **argv)
 		if (ioctl(fd, GUP_FAST_BENCHMARK, &gup))
 			perror("ioctl"), exit(1);
 
-		printf("Time: %lld us", gup.delta_usec);
+		printf("Time: get:%lld put:%lld us", gup.get_delta_usec,
+			gup.put_delta_usec);
 		if (gup.size != size)
 			printf(", truncated (size: %lld)", gup.size);
 		printf("\n");
-- 
2.14.4