On Wed, Jul 9, 2025 at 10:47 AM Suresh K C
<suresh.k.chandra...@gmail.com> wrote:
>
> From: Suresh K C <suresh.k.chandra...@gmail.com>
>
> This patch merges the previous two patches into a single,
> cohesive test case that verifies cachestat behavior with memory-mapped files
> using mmap().
> It also refactors the test logic to reduce redundancy, improve error
> reporting, and clarify failure messages for both shmem and mmap file types.
>
> Changes since v2:
>
> - Merged the two patches into one as suggested
> - Improved error messages for better clarity
>
> Tested on x86_64 with default kernel config.
>
> Signed-off-by: Suresh K C <suresh.k.chandra...@gmail.com>
> ---
> .../selftests/cachestat/test_cachestat.c | 66 +++++++++++++++----
> 1 file changed, 55 insertions(+), 11 deletions(-)
>
> diff --git a/tools/testing/selftests/cachestat/test_cachestat.c
> b/tools/testing/selftests/cachestat/test_cachestat.c
> index 632ab44737ec..18188d7c639e 100644
> --- a/tools/testing/selftests/cachestat/test_cachestat.c
> +++ b/tools/testing/selftests/cachestat/test_cachestat.c
> @@ -33,6 +33,11 @@ void print_cachestat(struct cachestat *cs)
> cs->nr_evicted, cs->nr_recently_evicted);
> }
>
> +enum file_type {
> + FILE_MMAP,
> + FILE_SHMEM
> +};
> +
> bool write_exactly(int fd, size_t filesize)
> {
> int random_fd = open("/dev/urandom", O_RDONLY);
> @@ -201,8 +206,19 @@ static int test_cachestat(const char *filename, bool
> write_random, bool create,
> out:
> return ret;
> }
> +const char* file_type_str(enum file_type type) {
> + switch (type) {
> + case FILE_SHMEM:
> + return "shmem";
> + case FILE_MMAP:
> + return "mmap";
> + default:
> + return "unknown";
> + }
> +}
>
> -bool test_cachestat_shmem(void)
> +
> +bool run_cachestat_test(enum file_type type)
> {
> size_t PS = sysconf(_SC_PAGESIZE);
> size_t filesize = PS * 512 * 2; /* 2 2MB huge pages */
> @@ -212,27 +228,49 @@ bool test_cachestat_shmem(void)
> char *filename = "tmpshmcstat";
> struct cachestat cs;
> bool ret = true;
> + int fd;
> unsigned long num_pages = compute_len / PS;
> - int fd = shm_open(filename, O_CREAT | O_RDWR, 0600);
> + if (type == FILE_SHMEM)
> + fd = shm_open(filename, O_CREAT | O_RDWR, 0600);
> + else
> + fd = open(filename, O_RDWR | O_CREAT | O_TRUNC, 0666);
>
> if (fd < 0) {
> - ksft_print_msg("Unable to create shmem file.\n");
> + ksft_print_msg("Unable to create %s
> file.\n",file_type_str(type));
> ret = false;
> goto out;
> }
>
> if (ftruncate(fd, filesize)) {
> - ksft_print_msg("Unable to truncate shmem file.\n");
> + ksft_print_msg("Unable to truncate %s
> file.\n",file_type_str(type));
> ret = false;
> goto close_fd;
> }
> -
> - if (!write_exactly(fd, filesize)) {
> - ksft_print_msg("Unable to write to shmem file.\n");
> - ret = false;
> - goto close_fd;
> + switch (type){
> + case FILE_SHMEM:
> + if (!write_exactly(fd, filesize)) {
> + ksft_print_msg("Unable to write to file.\n");
> + ret = false;
> + goto close_fd;
> + }
> + break;
> + case FILE_MMAP:
> + char *map = mmap(NULL, filesize, PROT_READ |
> PROT_WRITE, MAP_SHARED, fd, 0);
> + if (map == MAP_FAILED) {
> + ksft_print_msg("mmap failed.\n");
> + ret = false;
> + goto close_fd;
> + }
> + for (int i = 0; i < filesize; i++) {
> + map[i] = 'A';
> + }
> + break;
> + default:
> + ksft_print_msg("Unsupported file type.\n");
> + ret = false;
> + goto close_fd;
> + break;
> }
> -
> syscall_ret = syscall(__NR_cachestat, fd, &cs_range, &cs, 0);
>
> if (syscall_ret) {
> @@ -308,12 +346,18 @@ int main(void)
> break;
> }
>
> - if (test_cachestat_shmem())
> + if (run_cachestat_test(FILE_SHMEM))
> ksft_test_result_pass("cachestat works with a shmem file\n");
> else {
> ksft_test_result_fail("cachestat fails with a shmem file\n");
> ret = 1;
> }
>
> + if (run_cachestat_test(FILE_MMAP))
> + ksft_test_result_pass("cachestat works with a mmap file\n");
> + else {
> + ksft_test_result_fail("cachestat fails with a mmap file\n");
> + ret = 1;
> + }
> return ret;
> }
> --
> 2.43.0
>
Code LGTM, and the test passed on my system (x86-64 too though). FWIW:
Tested-by: Nhat Pham <npha...@gmail.com>
Acked-by: Nhat Pham <npha...@gmail.com>
Thanks for the test contribution, Suresh! And thanks for the review
help, Joshua :)
