On Fri, Sep 21, 2018 at 10:39:54PM +0000, Keith Busch wrote:
> The gup benchmark by default maps anonymous memory. This patch allows a
> user to specify a file to map, providing a means to test various
> file backings, like device and filesystem DAX.
>
> Cc: Kirill Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
> Cc: Dave Hansen <dave.hansen@xxxxxxxxx>
> Cc: Dan Williams <dan.j.williams@xxxxxxxxx>
> Signed-off-by: Keith Busch <keith.busch@xxxxxxxxx>
> ---
> tools/testing/selftests/vm/gup_benchmark.c | 19 ++++++++++++++++---
> 1 file changed, 16 insertions(+), 3 deletions(-)
>
> diff --git a/tools/testing/selftests/vm/gup_benchmark.c b/tools/testing/selftests/vm/gup_benchmark.c
> index b2082df8beb4..f2c99e2436f8 100644
> --- a/tools/testing/selftests/vm/gup_benchmark.c
> +++ b/tools/testing/selftests/vm/gup_benchmark.c
> @@ -33,9 +33,12 @@ int main(int argc, char **argv)
> unsigned long size = 128 * MB;
> int i, fd, opt, nr_pages = 1, thp = -1, repeats = 1, write = 0;
> int cmd = GUP_FAST_BENCHMARK;
> + int file_map = -1;
> + int flags = MAP_ANONYMOUS | MAP_PRIVATE;
> + char *file = NULL;
> char *p;
>
> - while ((opt = getopt(argc, argv, "m:r:n:tTLU")) != -1) {
> + while ((opt = getopt(argc, argv, "m:r:n:f:tTLU")) != -1) {
> switch (opt) {
> case 'm':
> size = atoi(optarg) * MB;
> @@ -61,11 +64,22 @@ int main(int argc, char **argv)
> case 'w':
> write = 1;
> break;
> + case 'f':
> + file = optarg;
> + flags &= ~(MAP_PRIVATE | MAP_ANONYMOUS);
> + flags |= MAP_SHARED;
Why do we want to assume shared mapping if a file is passed? Private-file
mapping is also valid target for the benchmark.
Maybe a separate option for shared? It would keep options more independent.
BTW, we can make a default file /dev/zero and don't have MAP_ANONYMOUS in
the flags: private mapping of /dev/zero would produce anonymous mapping.
No need in masking out MAP_ANONYMOUS on -f and no branch on 'if (file)'
below.
> + break;
> default:
> return -1;
> }
> }
>
> + if (file) {
> + file_map = open(file, O_RDWR|O_CREAT);
> + if (file_map < 0)
> + perror("open"), exit(file_map);
> + }
> +
> gup.nr_pages_per_call = nr_pages;
> gup.flags = write;
>
> @@ -73,8 +87,7 @@ int main(int argc, char **argv)
> if (fd == -1)
> perror("open"), exit(1);
>
> - p = mmap(NULL, size, PROT_READ | PROT_WRITE,
> - MAP_ANONYMOUS | MAP_PRIVATE, -1, 0);
> + p = mmap(NULL, size, PROT_READ | PROT_WRITE, flags, file_map, 0);
> if (p == MAP_FAILED)
> perror("mmap"), exit(1);
> gup.addr = (unsigned long)p;
> --
> 2.14.4
>
--
Kirill A. Shutemov
