mm/gup_benchmark.c: time put_page()

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

[akpm@linux-foundation.org: add expansion to struct gup_benchmark for future use]
Link: http://lkml.kernel.org/r/20181010195605.10689-1-keith.busch@intel.com
Signed-off-by: Keith Busch <keith.busch@intel.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 7 insertions, 2 deletions

diff --git a/mm/gup_benchmark.c b/mm/gup_benchmark.c
index 7405c9d89d65..e6aff102373b 100644
--- a/mm/gup_benchmark.c
+++ b/mm/gup_benchmark.c
@@ -8,11 +8,13 @@
 #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;
         __u32 flags;
+        __u64 expansion[10];    /* For future use */
 };
 
 static int __gup_benchmark_ioctl(unsigned int cmd,
@@ -48,14 +50,17 @@ 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;