Re: [PATCH] selftest/vm: Use correct PAGE_SHIFT value for ppc64

On 2/9/22 9:12 PM, Aneesh Kumar K.V wrote:

Shuah Khan [off-list ref] writes:

quoted

On 2/9/22 8:43 AM, Aneesh Kumar K.V wrote:

quoted

Keep it simple by using a #define and limiting hugepage size to 2M.
This keeps the test simpler instead of dynamically finding the page size
and huge page size.

Without this tests are broken w.r.t reading /proc/self/pagemap

	if (pread(pagemap_fd, ent, sizeof(ent),
			(uintptr_t)ptr >> (PAGE_SHIFT - 3)) != sizeof(ent))
		err(2, "read pagemap");

Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Aneesh Kumar K.V <redacted>
---
   tools/testing/selftests/vm/ksm_tests.c        | 8 ++++++++
   tools/testing/selftests/vm/transhuge-stress.c | 8 ++++++++
   2 files changed, 16 insertions(+)

diff --git a/tools/testing/selftests/vm/ksm_tests.c b/tools/testing/selftests/vm/ksm_tests.c
index 1436e1a9a3d3..8200328ff018 100644
--- a/tools/testing/selftests/vm/ksm_tests.c
+++ b/tools/testing/selftests/vm/ksm_tests.c

@@ -22,8 +22,16 @@
   #define KSM_MERGE_ACROSS_NODES_DEFAULT true
   #define MB (1ul << 20)
   
+#ifdef __powerpc64__
+#define PAGE_SHIFT	16
+/*
+ * This will only work with radix 2M hugepage size
+ */
+#define HPAGE_SHIFT 21
+#else
   #define PAGE_SHIFT 12
   #define HPAGE_SHIFT 21
+#endif
   
   #define PAGE_SIZE (1 << PAGE_SHIFT)
   #define HPAGE_SIZE (1 << HPAGE_SHIFT)

diff --git a/tools/testing/selftests/vm/transhuge-stress.c b/tools/testing/selftests/vm/transhuge-stress.c
index 5e4c036f6ad3..f04c8aa4bcf6 100644
--- a/tools/testing/selftests/vm/transhuge-stress.c
+++ b/tools/testing/selftests/vm/transhuge-stress.c

@@ -16,8 +16,16 @@
   #include <string.h>
   #include <sys/mman.h>
   
+#ifdef __powerpc64__
+#define PAGE_SHIFT	16
+/*
+ * This will only work with radix 2M hugepage size
+ */
+#define HPAGE_SHIFT 21

Why not have this is in common code?

Can you suggest where I can move that. We also have helper functions
like allocate_transhuge() duplicated between tests. I didn't find
libutil.a or anything similar supported by the selftets build.

quoted

I noticed that HPAGE_SHIFT is defined in #ifdef __powerpc64__ block
as well as #else. I am asking is it necessary to be part of both
blocks.

+#ifdef __powerpc64__
+#define PAGE_SHIFT	16
+/*
+ * This will only work with radix 2M hugepage size
+ */
+#define HPAGE_SHIFT 21  --- this one
+#else
   #define PAGE_SHIFT 12
   #define HPAGE_SHIFT 21   --- this one
+#endif


Hope this helps.

thanks,
-- Shuah