Changeset b60615b in mainline

Timestamp:

2018-11-13T16:48:08Z (6 years ago)

Author:

Jiří Zárevúcky <zarevucky.jiri@…>

Branches:

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

Children:

71fb5ac

Parents:

159c1525

git-author:

Jiří Zárevúcky <zarevucky.jiri@…> (2018-11-11 17:03:50)

git-committer:

Jiří Zárevúcky <zarevucky.jiri@…> (2018-11-13 16:48:08)

Message:

Modify kernel malloc()

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 improve scalability and 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).

Location:

kernel

Files:

• Makefile (modified) (2 diffs)
• generic/include/bitops.h (modified) (1 diff)
• generic/include/main/main.h (modified) (1 diff)
• generic/include/mm/slab.h (modified) (1 diff)
• generic/src/main/main.c (modified) (1 diff)
• generic/src/mm/malloc.c (added)
• generic/src/mm/slab.c (modified) (4 diffs)

kernel/Makefile

@@ -94 +94 @@
         -fdebug-prefix-map=$(realpath $(ROOT_PATH))=.
 
-GCC_CFLAGS = -std=gnu99 -Wall -Wextra -Wno-unused-parameter \
+GCC_CFLAGS = -std=gnu11 -Wall -Wextra -Wno-unused-parameter \
         -Wmissing-prototypes -Werror-implicit-function-declaration \
         -Wwrite-strings -pipe -Wno-cast-function-type
 
-CLANG_CFLAGS = -std=gnu99 -Wall -Wextra -Wno-unused-parameter \
+CLANG_CFLAGS = -std=gnu11 -Wall -Wextra -Wno-unused-parameter \
         -Wno-missing-field-initializers -Wno-unused-command-line-argument \
         -Wmissing-prototypes -Werror-implicit-function-declaration \
@@ -197 +197 @@
         generic/src/mm/tlb.c \
         generic/src/mm/as.c \
+        generic/src/mm/malloc.c \
         generic/src/mm/backend_anon.c \
         generic/src/mm/backend_elf.c \

kernel/generic/include/bitops.h

@@ -36 +36 @@
 #define KERN_BITOPS_H_
 
+#include <stdint.h>
 #include <trace.h>
 

kernel/generic/include/main/main.h

@@ -48 +48 @@
 extern void main_ap(void);
 
+extern void malloc_init(void);
+
 #endif
 

kernel/generic/include/mm/slab.h

@@ -40 +40 @@
 #include <atomic.h>
 #include <mm/frame.h>
-
-/** Minimum size to be allocated by malloc */
-#define SLAB_MIN_MALLOC_W  4
-
-/** Maximum size to be allocated by malloc */
-#define SLAB_MAX_MALLOC_W  22
 
 /** Initial Magazine size (TODO: dynamically growing magazines) */

kernel/generic/src/main/main.c

@@ -246 +246 @@
         frame_init();
         slab_cache_init();
+        malloc_init();
         ra_init();
         sysinfo_init();

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);
-}
-
 /** @}
  */