Re: [PATCH] selftests: cachestat: add mmap test and /proc/cpuinfo test case

On 5/16/25 06:41, Suresh K C wrote:

From: Suresh K C suresh.k.chandrappa@gmail.com

This patch adds a new test case to validate cachestat behavior with

Add a new test case

memory-mapped files using mmap(). The test ensures that pages are properly cached when accessed via mmap and verifies the expected number of cached pages.

Additionally, a test case for /proc/cpuinfo has been added to observe how cachestat handles virtual files under /proc. This helps improve coverage of edge cases involving pseudo-filesystems

Signed-off-by: Suresh K C suresh.k.chandrappa@gmail.com

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---

.../selftests/cachestat/test_cachestat.c | 69 ++++++++++++++++++- 1 file changed, 67 insertions(+), 2 deletions(-)

diff --git a/tools/testing/selftests/cachestat/test_cachestat.c b/tools/testing/selftests/cachestat/test_cachestat.c index 632ab44737ec..81e7f6dd2279 100644 --- a/tools/testing/selftests/cachestat/test_cachestat.c +++ b/tools/testing/selftests/cachestat/test_cachestat.c @@ -22,7 +22,7 @@ static const char * const dev_files[] = { "/dev/zero", "/dev/null", "/dev/urandom",

• "/proc/version", "/proc"

• "/proc/version","/proc/cpuinfo","/proc" };

void print_cachestat(struct cachestat *cs) @@ -202,6 +202,65 @@ static int test_cachestat(const char *filename, bool write_random, bool create, return ret; } +bool test_cachestat_mmap(void){

• size_t PS = sysconf(_SC_PAGESIZE);
• size_t filesize = PS * 512 * 2;;
• int syscall_ret;
• size_t compute_len = PS * 512;
• struct cachestat_range cs_range = { PS, compute_len };
• char *filename = "tmpshmcstat";
• unsigned long num_pages = compute_len / PS;
• struct cachestat cs;
• bool ret = true;
• int fd = open(filename, O_RDWR | O_CREAT | O_TRUNC, 0666);
• if (fd < 0) {

• ksft_print_msg("Unable to create mmap file.\n");
  

• ret = false;
  

• goto out;
  

• }
• if (ftruncate(fd, filesize)) {

• ksft_print_msg("Unable to truncate mmap file.\n");
  

• ret = false;
  

• goto close_fd;
  

• }
• if (!write_exactly(fd, filesize)) {

• ksft_print_msg("Unable to write to mmap file.\n");
  

• ret = false;
  

• goto close_fd;
  

• }
• 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';
  

• }
• map[filesize - 1] = 'X';
• syscall_ret = syscall(__NR_cachestat, fd, &cs_range, &cs, 0);
• if (syscall_ret) {

• ksft_print_msg("Cachestat returned non-zero.\n");
  

• ret = false;
  

• } else {

• print_cachestat(&cs);
  

• if (cs.nr_cache + cs.nr_evicted != num_pages) {
  

• 	ksft_print_msg("Total number of cached and evicted pages is off.\n");
  

• 	ret = false;
  

• }
  

• }

+close_fd:

• close(fd);
• unlink(filename);

+out:

• return ret;

+}

• bool test_cachestat_shmem(void) { size_t PS = sysconf(_SC_PAGESIZE);

@@ -274,7 +333,7 @@ int main(void) ret = 1; }

• for (int i = 0; i < 5; i++) {

• for (int i = 0; i < 6; i++) { const char *dev_filename = dev_files[i];

if (test_cachestat(dev_filename, false, false, false, @@ -315,5 +374,11 @@ int main(void) ret = 1; }

• if (test_cachestat_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; }

thanks, -- Shuah