Re: [RFC PATCH v4 6/9] KVM: selftests: Add a helper to get system default hugetlb page size

[wangyanan (Y)]

On 2021/3/12 19:40, Andrew Jones wrote:

On Tue, Mar 02, 2021 at 08:57:48PM +0800, Yanan Wang wrote:

If HUGETLB is configured in the host kernel, then we can know the system
default hugetlb page size through *cat /proc/meminfo*. Otherwise, we will
not see the information of hugetlb pages in file /proc/meminfo if it's not
configured. So add a helper to determine whether HUGETLB is configured and
then get the default page size by reading /proc/meminfo.

This helper can be useful when a program wants to use the default hugetlb
pages of the system and doesn't know the default page size.

Signed-off-by: Yanan Wang <wangyana...@huawei.com>
---
  .../testing/selftests/kvm/include/test_util.h |  1 +
  tools/testing/selftests/kvm/lib/test_util.c   | 27 +++++++++++++++++++
  2 files changed, 28 insertions(+)

diff --git a/tools/testing/selftests/kvm/include/test_util.h 
b/tools/testing/selftests/kvm/include/test_util.h
index ef24c76ba89a..e087174eefe5 100644
--- a/tools/testing/selftests/kvm/include/test_util.h
+++ b/tools/testing/selftests/kvm/include/test_util.h
@@ -80,6 +80,7 @@ struct vm_mem_backing_src_alias {

bool thp_configured(void);

  size_t get_trans_hugepagesz(void);
+size_t get_def_hugetlb_pagesz(void);
  void backing_src_help(void);
  enum vm_mem_backing_src_type parse_backing_src_type(const char *type_name);

diff --git a/tools/testing/selftests/kvm/lib/test_util.c b/tools/testing/selftests/kvm/lib/test_util.c

index f2d133f76c67..80d68dbd72d2 100644
--- a/tools/testing/selftests/kvm/lib/test_util.c
+++ b/tools/testing/selftests/kvm/lib/test_util.c
@@ -153,6 +153,33 @@ size_t get_trans_hugepagesz(void)
        return size;
  }

+size_t get_def_hugetlb_pagesz(void)

+{
+       char buf[64];
+       const char *tag = "Hugepagesize:";
+       FILE *f;
+
+       f = fopen("/proc/meminfo", "r");
+       TEST_ASSERT(f != NULL, "Error in opening /proc/meminfo: %d", errno);
+
+       while (fgets(buf, sizeof(buf), f) != NULL) {
+               if (strstr(buf, tag) == buf) {
+                       fclose(f);
+                       return strtoull(buf + strlen(tag), NULL, 10) << 10;
+               }
+       }
+
+       if (feof(f)) {
+               fclose(f);
+               TEST_FAIL("HUGETLB is not configured in host kernel");
+       } else {
+               fclose(f);
+               TEST_FAIL("Error in reading /proc/meminfo: %d", errno);
+       }

fclose() can be factored out.

+
+       return 0;
+}
+
  void backing_src_help(void)
  {
        int i;
--
2.23.0

Besides the fclose comment and the same errno comment as the previous
patch

I will fix it and add your R-b in this patch.

Thanks,
Yanan

Reviewed-by: Andrew Jones <drjo...@redhat.com>

.