WebSVN – HelenOS-historic – Diff – /kernel/trunk/generic/src/mm/buddy.c

 /*
  * Copyright (C) 2005 Jakub Jermar
  * All rights reserved.
+ *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
+ *
  * - Redistributions of source code must retain the above copyright
  *   notice, this list of conditions and the following disclaimer.
  * - Redistributions in binary form must reproduce the above copyright
  *   notice, this list of conditions and the following disclaimer in the
  *   documentation and/or other materials provided with the distribution.
  * - The name of the author may not be used to endorse or promote products
  *   derived from this software without specific prior written permission.
+ *
  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 #include <mm/buddy.h>
 #include <mm/frame.h>
-#include <mm/heap.h>
 #include <arch/types.h>
 #include <typedefs.h>
 #include <adt/list.h>
 #include <debug.h>
 #include <print.h>
+/** Return size needed for the buddy configuration data */
+size_t buddy_conf_size(int max_order)
+{
+    return sizeof(buddy_system_t) + (max_order + 1) * sizeof(link_t);
+}
 /** Create buddy system
+ *
  * Allocate memory for and initialize new buddy system.
+ *
+ * @param b Preallocated buddy system control data
  * @param max_order The biggest allocable size will be 2^max_order.
  * @param op Operations for new buddy system.
  * @param data Pointer to be used by implementation.
+ *
  * @return New buddy system.
  */
-buddy_system_t *buddy_system_create(__u8 max_order, buddy_system_operations_t *op, void *data)
+void buddy_system_create(buddy_system_t *b,
+             __u8 max_order,
+             buddy_system_operations_t *op,
+             void *data)
+{
-    buddy_system_t *b;
     int i;
     ASSERT(max_order < BUDDY_SYSTEM_INNER_BLOCK);
     ASSERT(op->find_buddy);
     ASSERT(op->set_order);
     ASSERT(op->get_order);
     ASSERT(op->bisect);
     ASSERT(op->coalesce);
     ASSERT(op->mark_busy);
     /*
-     * Allocate memory for structure describing the whole buddy system.
-     */
-    b = (buddy_system_t *) early_malloc(sizeof(buddy_system_t));
-    if (b) {
-        /*
-         * Allocate memory for all orders this buddy system will work with.
+     * Use memory after our own structure
-         */
+     */
-        b->order = (link_t *) early_malloc((max_order + 1) * sizeof(link_t));
-        if (!b->order) {
-            early_free(b);
-            return NULL;
-        }
-        for (i = 0; i <= max_order; i++)
-            list_initialize(&b->order[i]);
-        b->max_order = max_order;
+    b->order = (link_t *) (&b[1]);
-        b->op = op;
-        b->data = data;
-    }
+    for (i = 0; i <= max_order; i++)
+        list_initialize(&b->order[i]);
+    b->max_order = max_order;
-    return b;
+    b->op = op;
+    b->data = data;
+}
 /** Check if buddy system can allocate block
+ *
  * @param b Buddy system pointer
  * @param i Size of the block (2^i)
+ *
  * @return True if block can be allocated
  */
 bool buddy_system_can_alloc(buddy_system_t *b, __u8 i) {
     __u8 k;
     /*
      * If requested block is greater then maximal block
      * we know immediatly that we cannot satisfy the request.
      */
     if (i > b->max_order) return false;
     /*
      * Check if any bigger or equal order has free elements
      */
     for (k=i; k <= b->max_order; k++) {
         if (!list_empty(&b->order[k])) {
             return true;
+        }
+    }
     return false;
+}
+/** Allocate PARTICULAR block from buddy system
+ *
+ * @ return Block of data or NULL if no such block was found
+ */
+link_t *buddy_system_alloc_block(buddy_system_t *b, link_t *block)
+{
+    link_t *left,*right, *tmp;
+    __u8 order;
+    left = b->op->find_block(b, block, BUDDY_SYSTEM_INNER_BLOCK);
+    ASSERT(left);
+    list_remove(left);
+    while (1) {
+        if (! b->op->get_order(b,left)) {
+            b->op->mark_busy(b, left);
+            return left;
+        }
+        order = b->op->get_order(b, left);
+        right = b->op->bisect(b, left);
+        b->op->set_order(b, left, order-1);
+        b->op->set_order(b, right, order-1);
+        tmp = b->op->find_block(b, block, BUDDY_SYSTEM_INNER_BLOCK);
+        if (tmp == right) {
+            right = left;
+            left = tmp;
+        }
+        b->op->mark_busy(b, left);
+        buddy_system_free(b, right);
+        b->op->mark_available(b, left);
+    }
+}
 /** Allocate block from buddy system.
+ *
  * @param b Buddy system pointer.
  * @param i Returned block will be 2^i big.
+ *
  * @return Block of data represented by link_t.
  */
 link_t *buddy_system_alloc(buddy_system_t *b, __u8 i)
+{
     link_t *res, *hlp;
     ASSERT(i <= b->max_order);
     /*
      * If the list of order i is not empty,
      * the request can be immediatelly satisfied.
      */
     if (!list_empty(&b->order[i])) {
         res = b->order[i].next;
         list_remove(res);
         b->op->mark_busy(b, res);
         return res;
+    }
     /*
      * If order i is already the maximal order,
      * the request cannot be satisfied.
      */
     if (i == b->max_order)
         return NULL;
     /*
      * Try to recursively satisfy the request from higher order lists.
      */
     hlp = buddy_system_alloc(b, i + 1);
     /*
      * The request could not be satisfied
      * from higher order lists.
      */
     if (!hlp)
         return NULL;
     res = hlp;
     /*
      * Bisect the block and set order of both of its parts to i.
      */
     hlp = b->op->bisect(b, res);
     b->op->set_order(b, res, i);
     b->op->set_order(b, hlp, i);
     /*
-     * Return the other half to buddy system.
+     * Return the other half to buddy system. Mark the first part
-     * PROBLEM!!!! WILL FIND OTHER PART AS BUDDY AND LINK TOGETHER
+     * full, so that it won't coalsce again.
      */
     b->op->mark_busy(b, res);
     buddy_system_free(b, hlp);
     return res;
+}
 /** Return block to buddy system.
+ *
  * @param b Buddy system pointer.
  * @param block Block to return.
  */
 void buddy_system_free(buddy_system_t *b, link_t *block)
+{
     link_t *buddy, *hlp;
     __u8 i;
     /*
      * Determine block's order.
      */
     i = b->op->get_order(b, block);
     ASSERT(i <= b->max_order);
     if (i != b->max_order) {
         /*
          * See if there is any buddy in the list of order i.
          */
         buddy = b->op->find_buddy(b, block);
         if (buddy) {
             ASSERT(b->op->get_order(b, buddy) == i);
             /*
              * Remove buddy from the list of order i.
              */
             list_remove(buddy);
             /*
              * Invalidate order of both block and buddy.
              */
             b->op->set_order(b, block, BUDDY_SYSTEM_INNER_BLOCK);
             b->op->set_order(b, buddy, BUDDY_SYSTEM_INNER_BLOCK);
             /*
              * Coalesce block and buddy into one block.
              */
             hlp = b->op->coalesce(b, block, buddy);
             /*
              * Set order of the coalesced block to i + 1.
              */
             b->op->set_order(b, hlp, i + 1);
             /*
              * Recursively add the coalesced block to the list of order i + 1.
              */
             buddy_system_free(b, hlp);
             return;
+        }
+    }
     /*
      * Insert block into the list of order i.
      */
     list_append(block, &b->order[i]);
+}
 /** Prints out structure of buddy system
+ *
  * @param b Pointer to buddy system
  * @param es Element size
  */
 void buddy_system_structure_print(buddy_system_t *b, size_t elem_size) {
     index_t i;
     count_t cnt, elem_count = 0, block_count = 0;
     link_t * cur;
     printf("Order\tBlocks\tSize    \tBlock size\tElems per block\n");
     printf("-----\t------\t--------\t----------\t---------------\n");
     for (i=0;i <= b->max_order; i++) {
         cnt = 0;
         if (!list_empty(&b->order[i])) {
             for (cur = b->order[i].next; cur != &b->order[i]; cur = cur->next)
                 cnt++;
+        }
         printf("#%d\t%d\t%dK\t\t%dK\t\t%d\n", i, cnt, (cnt * (1 << i) * elem_size) >> 10, ((1 << i) * elem_size) >> 10, 1 << i);
         block_count += cnt;
         elem_count += (1 << i) * cnt;
+    }
     printf("-----\t------\t--------\t----------\t---------------\n");
     printf("Buddy system contains %d free elements (%d blocks)\n" , elem_count, block_count);
+}

Subversion Repositories HelenOS-historic

(root)/kernel/trunk/generic/src/mm/buddy.c – Rev 813 → 814