util: introduce physical_memory_scale() to unify how we scale by physical memory

The various bits of code did the scaling all different, let's unify this,
given that the code is not trivial.

1 files changed, 37 insertions, 1 deletions

diff --git a/src/test/test-util.c b/src/test/test-util.c
index 5b3fbcff53..e177612a9f 100644
--- a/src/test/test-util.c
+++ b/src/test/test-util.c
@@ -273,7 +273,42 @@ static void test_physical_memory(void) {
         assert_se(p < UINT64_MAX);
         assert_se(p % page_size() == 0);
 
-        log_info("Memory: %s", format_bytes(buf, sizeof(buf), p));
+        log_info("Memory: %s (%" PRIu64 ")", format_bytes(buf, sizeof(buf), p), p);
+}
+
+static void test_physical_memory_scale(void) {
+        uint64_t p;
+
+        p = physical_memory();
+
+        assert_se(physical_memory_scale(0, 100) == 0);
+        assert_se(physical_memory_scale(100, 100) == p);
+
+        log_info("Memory original: %" PRIu64, physical_memory());
+        log_info("Memory scaled by 50%%: %" PRIu64, physical_memory_scale(50, 100));
+        log_info("Memory divided by 2: %" PRIu64, physical_memory() / 2);
+        log_info("Page size: %zu", page_size());
+
+        /* There might be an uneven number of pages, hence permit these calculations to be half a page off... */
+        assert_se(page_size()/2 + physical_memory_scale(50, 100) - p/2 <= page_size());
+        assert_se(physical_memory_scale(200, 100) == p*2);
+
+        assert_se(physical_memory_scale(0, 1) == 0);
+        assert_se(physical_memory_scale(1, 1) == p);
+        assert_se(physical_memory_scale(2, 1) == p*2);
+
+        assert_se(physical_memory_scale(0, 2) == 0);
+
+        assert_se(page_size()/2 + physical_memory_scale(1, 2) - p/2 <= page_size());
+        assert_se(physical_memory_scale(2, 2) == p);
+        assert_se(physical_memory_scale(4, 2) == p*2);
+
+        assert_se(physical_memory_scale(0, UINT32_MAX) == 0);
+        assert_se(physical_memory_scale(UINT32_MAX, UINT32_MAX) == p);
+
+        /* overflow */
+        assert_se(physical_memory_scale(UINT64_MAX/4, UINT64_MAX) == UINT64_MAX);
+
 }
 
 int main(int argc, char *argv[]) {
@@ -291,6 +326,7 @@ int main(int argc, char *argv[]) {
         test_execute_directory();
         test_raw_clone();
         test_physical_memory();
+        test_physical_memory_scale();
 
         return 0;
 }