From 53369ab5645b9bb26846adc7a4b7a0535caa8978 Mon Sep 17 00:00:00 2001
From: Aurel Feer <aurel.feer@gmail.com>
Date: Mon, 11 Apr 2022 18:27:16 +0200
Subject: [PATCH] alloc and free many small buffers

---
 lib/mm/mm.c           |  7 ++++++-
 usr/mallocator/main.c | 42 +++++++++++++++++++++++++++++++++++-------
 2 files changed, 41 insertions(+), 8 deletions(-)

diff --git a/lib/mm/mm.c b/lib/mm/mm.c
index d470880..bf033bf 100644
--- a/lib/mm/mm.c
+++ b/lib/mm/mm.c
@@ -34,7 +34,7 @@ struct mm_root_node {
     mm_leaf_node_t *leafs[MM_LEAF_COUNT];
 };
 STATIC_ASSERT(sizeof(struct mm_root_node) <= MM_BLOCK_SIZE, "struct mm_root_node too big");
-
+static size_t number_of_bytes_allocated = 0;
 
 errval_t mm_init(struct mm *mm, enum objtype objtype,
                      slab_refill_func_t slab_refill_func,
@@ -120,6 +120,11 @@ errval_t mm_add(struct mm *mm, struct capref cap)
 errval_t mm_alloc_aligned(struct mm *mm, size_t size, size_t alignment, struct capref *retcap)
 {
     errval_t err;
+
+    //TODO afeer: remove this after evaluation
+    number_of_bytes_allocated += size;
+    // debug_printf("[mm] number_of_bytes_allocated: %x\n", number_of_bytes_allocated);
+
     if ((alignment & (alignment - 1)) != 0) {
         return MM_ERR_BAD_ALIGNMENT;
     }
diff --git a/usr/mallocator/main.c b/usr/mallocator/main.c
index 4a7f459..bc03868 100644
--- a/usr/mallocator/main.c
+++ b/usr/mallocator/main.c
@@ -18,16 +18,44 @@
 #include <aos/aos.h>
 #include <aos/paging.h>
 
-int main(int argc, char *argv[])
-{
-    //allocate a 256 byte buffer
-    // char * small_buf = malloc(256);
-    // small_buf[0] = 'a';
+#define NUM_SMALL_BUFFERS 128
+
+static void test_large_buffer(void) {
     //allocate a 256 MiB buffer
+    debug_printf("allocating 256MiB buffer\n");
     char * big_buf = malloc(1<<28);
     big_buf[0] = 'a';
-    for (int i = 0; i < (1 << 16); i += 4096) {
-        debug_printf("%x\n", i);
+
+    //only write to a small part of the large buffer
+    for (int i = 0; i < (1 << 16); i += (1 << 12)) {
         big_buf[i] = 'b';
     }
+
+    debug_printf("freeing 256MiB buffer\n");
+    free(big_buf);
+}
+
+static void test_many_buffers(void) {
+
+    char* buffers[NUM_SMALL_BUFFERS];
+
+    for (int i = 0; i < NUM_SMALL_BUFFERS; ++i) {
+        buffers[i] = malloc(4 * BASE_PAGE_SIZE);
+    }
+
+    //free the buffers in a different order
+    for (int i = NUM_SMALL_BUFFERS - 1; i >= NUM_SMALL_BUFFERS / 2; --i) {
+        free(buffers[i]);
+    }
+    for (int i = 0; i < NUM_SMALL_BUFFERS / 2; ++i) {
+        free(buffers[i]);
+    }
+}
+
+int main(int argc, char *argv[])
+{
+    test_large_buffer();
+    test_many_buffers();
+
+    debug_printf("i am done!\n");
 }
\ No newline at end of file