Re: [PATCH] selftests: get readahead size for check_file_mmap()

On 3/30/21 6:45 AM, JeffleXu wrote:

On 3/30/21 8:40 PM, Jeffle Xu wrote:

...

The readahead size used to be 2MB, thus it's reasonable to set the file size as 4MB when checking check_file_mmap().

However since commit c2e4cd57cfa1 ("block: lift setting the readahead size into the block layer"), readahead could be as large as twice the io_opt, and thus the hardcoded file size no longer works.

Signed-off-by: Jeffle Xu jefflexu@linux.alibaba.com

Forgot to mention that otherwise, "Read-ahead pages reached the end of the file" is reported in check_file_mmap().

Please update the change log and send v2 including the change history.

...

---

.../selftests/mincore/mincore_selftest.c | 57 +++++++++++++++---- 1 file changed, 47 insertions(+), 10 deletions(-)

Please include test name in the subject line

...

diff --git a/tools/testing/selftests/mincore/mincore_selftest.c b/tools/testing/selftests/mincore/mincore_selftest.c index 5a1e85ff5d32..cf0c86697403 100644 --- a/tools/testing/selftests/mincore/mincore_selftest.c +++ b/tools/testing/selftests/mincore/mincore_selftest.c @@ -15,6 +15,11 @@ #include <string.h> #include <fcntl.h> #include <string.h> +#include <sys/types.h> +#include <sys/stat.h> +#include <sys/ioctl.h> +#include <sys/sysmacros.h> +#include <sys/mount.h> #include "../kselftest.h" #include "../kselftest_harness.h" @@ -195,10 +200,42 @@ TEST(check_file_mmap) int fd; int i; int ra_pages = 0;

• long ra_size, filesize;
• struct stat stats;
• dev_t devt;
• unsigned int major, minor;
• char devpath[32];
• retval = stat(".", &stats);
• ASSERT_EQ(0, retval) {

• TH_LOG("Can't stat pwd: %s", strerror(errno));
  

• }
• devt = stats.st_dev;
• major = major(devt);
• minor = minor(devt);
• snprintf(devpath, sizeof(devpath), "/dev/block/%u:%u", major, minor);
• fd = open(devpath, O_RDONLY);
• ASSERT_NE(-1, fd) {

• TH_LOG("Can't open underlying disk %s", strerror(errno));
  

• }
• retval = ioctl(fd, BLKRAGET, &ra_size);
• ASSERT_EQ(0, retval) {

• TH_LOG("Error ioctl with the underlying disk: %s", strerror(errno));
  

• }
• /*

• * BLKRAGET ioctl returns the readahead size in sectors (512 bytes).
  

• * Make filesize large enough to contain the readahead window.
  

• */
  

• ra_size *= 512;
• filesize = ra_size * 2;

page_size = sysconf(_SC_PAGESIZE);

• vec_size = FILE_SIZE / page_size;
• if (FILE_SIZE % page_size)

• vec_size = filesize / page_size;
• if (filesize % page_size) vec_size++;

vec = calloc(vec_size, sizeof(unsigned char)); @@ -213,7 +250,7 @@ TEST(check_file_mmap) strerror(errno)); } errno = 0;

• retval = fallocate(fd, 0, 0, FILE_SIZE);

• retval = fallocate(fd, 0, 0, filesize); ASSERT_EQ(0, retval) { TH_LOG("Error allocating space for the temporary file: %s", strerror(errno));

@@ -223,12 +260,12 @@ TEST(check_file_mmap) * Map the whole file, the pages shouldn't be fetched yet. */ errno = 0;

• addr = mmap(NULL, FILE_SIZE, PROT_READ | PROT_WRITE,

• addr = mmap(NULL, filesize, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0); ASSERT_NE(MAP_FAILED, addr) { TH_LOG("mmap error: %s", strerror(errno)); }

• retval = mincore(addr, FILE_SIZE, vec);

• retval = mincore(addr, filesize, vec); ASSERT_EQ(0, retval); for (i = 0; i < vec_size; i++) { ASSERT_EQ(0, vec[i]) {

@@ -240,14 +277,14 @@ TEST(check_file_mmap) * Touch a page in the middle of the mapping. We expect the next * few pages (the readahead window) to be populated too. */

• addr[FILE_SIZE / 2] = 1;
• retval = mincore(addr, FILE_SIZE, vec);

• addr[filesize / 2] = 1;
• retval = mincore(addr, filesize, vec); ASSERT_EQ(0, retval);

• ASSERT_EQ(1, vec[FILE_SIZE / 2 / page_size]) {

• ASSERT_EQ(1, vec[filesize / 2 / page_size]) { TH_LOG("Page not found in memory after use"); }

• i = FILE_SIZE / 2 / page_size + 1;

• i = filesize / 2 / page_size + 1; while (i < vec_size && vec[i]) { ra_pages++; i++;

@@ -271,7 +308,7 @@ TEST(check_file_mmap) } }

• munmap(addr, FILE_SIZE);

• munmap(addr, filesize); close(fd); free(vec); }

thanks, -- Shuah