Changeset b0beb9b1 in mainline for kernel/generic/src/mm/slab.c

Timestamp:

2018-11-16T15:34:08Z (5 years ago)

Author:

GitHub <noreply@…>

Branches:

lfn, master, serial, ticket/834-toolchain-update, topic/msim-upgrade, topic/simplify-dev-export

Children:

d230358

Parents:

64f85f5 (diff), bcd4dd4 (diff)
Note: this is a merge changeset, the changes displayed below correspond to the merge itself.
Use the (diff) links above to see all the changes relative to each parent.

git-author:

Jiří Zárevúcky <zarevucky.jiri@…> (2018-11-16 15:34:08)

git-committer:

GitHub <noreply@…> (2018-11-16 15:34:08)

Message:

Modify kernel malloc() (#58)

This new implementation places the allocation size in front of the allocated
object, instead of relying on the slab allocator being able to determine source
slab cache for an object. This should help reduce complexity of the memory
management subsystem (further changes coming).

The drawback is more memory consumed by small malloc() allocations, however that
can be mitigated by switching to an API where the user provides known object
size to deallocation (most users know it either statically or from length they
necessarily remember).

File:

• kernel/generic/src/mm/slab.c (modified) (4 diffs)

kernel/generic/src/mm/slab.c

@@ -138 +138 @@
 static slab_cache_t *slab_extern_cache;
 
-/** Caches for malloc */
-static slab_cache_t *malloc_caches[SLAB_MAX_MALLOC_W - SLAB_MIN_MALLOC_W + 1];
-
-static const char *malloc_names[] =  {
-        "malloc-16",
-        "malloc-32",
-        "malloc-64",
-        "malloc-128",
-        "malloc-256",
-        "malloc-512",
-        "malloc-1K",
-        "malloc-2K",
-        "malloc-4K",
-        "malloc-8K",
-        "malloc-16K",
-        "malloc-32K",
-        "malloc-64K",
-        "malloc-128K",
-        "malloc-256K",
-        "malloc-512K",
-        "malloc-1M",
-        "malloc-2M",
-        "malloc-4M"
-};
-
 /** Slab descriptor */
 typedef struct {
@@ -775 +750 @@
                 panic("Destroying cache that is not empty.");
 
-        if (!(cache->flags & SLAB_CACHE_NOMAGAZINE)) {
-                slab_t *mag_slab = obj2slab(cache->mag_cache);
-                _slab_free(mag_slab->cache, cache->mag_cache, mag_slab);
+        if (!(cache->flags & SLAB_CACHE_NOMAGAZINE) && cache->mag_cache) {
+                slab_free(&slab_mag_cache, cache->mag_cache);
         }
 
@@ -914 +888 @@
             NULL, NULL, SLAB_CACHE_SLINSIDE | SLAB_CACHE_MAGDEFERRED);
 
-        /* Initialize structures for malloc */
-        size_t i;
-        size_t size;
-
-        for (i = 0, size = (1 << SLAB_MIN_MALLOC_W);
-            i < (SLAB_MAX_MALLOC_W - SLAB_MIN_MALLOC_W + 1);
-            i++, size <<= 1) {
-                malloc_caches[i] = slab_cache_create(malloc_names[i], size, 0,
-                    NULL, NULL, SLAB_CACHE_MAGDEFERRED);
-        }
-
 #ifdef CONFIG_DEBUG
         _slab_initialized = 1;
@@ -961 +924 @@
 }
 
-void *malloc(size_t size)
-{
-        assert(_slab_initialized);
-        assert(size <= (1 << SLAB_MAX_MALLOC_W));
-
-        if (size < (1 << SLAB_MIN_MALLOC_W))
-                size = (1 << SLAB_MIN_MALLOC_W);
-
-        uint8_t idx = fnzb(size - 1) - SLAB_MIN_MALLOC_W + 1;
-
-        return slab_alloc(malloc_caches[idx], FRAME_ATOMIC);
-}
-
-void *realloc(void *ptr, size_t size)
-{
-        assert(_slab_initialized);
-        assert(size <= (1 << SLAB_MAX_MALLOC_W));
-
-        void *new_ptr;
-
-        if (size > 0) {
-                if (size < (1 << SLAB_MIN_MALLOC_W))
-                        size = (1 << SLAB_MIN_MALLOC_W);
-                uint8_t idx = fnzb(size - 1) - SLAB_MIN_MALLOC_W + 1;
-
-                new_ptr = slab_alloc(malloc_caches[idx], FRAME_ATOMIC);
-        } else
-                new_ptr = NULL;
-
-        if ((new_ptr != NULL) && (ptr != NULL)) {
-                slab_t *slab = obj2slab(ptr);
-                memcpy(new_ptr, ptr, min(size, slab->cache->size));
-        }
-
-        if (ptr != NULL)
-                free(ptr);
-
-        return new_ptr;
-}
-
-void free(void *ptr)
-{
-        if (!ptr)
-                return;
-
-        slab_t *slab = obj2slab(ptr);
-        _slab_free(slab->cache, ptr, slab);
-}
-
 /** @}
  */