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

Hi Ms.Khan

I have added a new api *test_cachestat_mmap *to validate cachestat behavior with memory-mapped files. attached the output file here.

Thanks, Suresh K C

On Fri, May 16, 2025 at 6:12 PM Suresh K C suresh.k.chandrappa@gmail.com wrote:

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

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

.../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;
  

}

2.43.0