Changeset 010be476 in mainline for kernel/generic/src/mm/reserve.c

Timestamp:

2011-04-21T19:27:02Z (13 years ago)

Author:

Jakub Jermar <jakub@…>

Branches:

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

Children:

7da90cd, d61c3a7

Parents:

864b0dd

Message:

In case of no reserve in reserve_try_alloc(), attempt to reclaim
reservable memory from the slab allocator.

Add doxygen comments.

File:

• kernel/generic/src/mm/reserve.c (modified) (5 diffs)

kernel/generic/src/mm/reserve.c

@@ -38 +38 @@
 #include <mm/reserve.h>
 #include <mm/frame.h>
+#include <mm/slab.h>
 #include <synch/spinlock.h>
 #include <typedefs.h>
@@ -45 +46 @@
 static ssize_t reserve = 0;
 
+/** Try to reserve memory.
+ *
+ * This function may not be called from contexts that do not allow memory
+ * reclaiming, such as some invocations of frame_alloc_generic().
+ *
+ * @param size          Number of frames to reserve.
+ * @return              True on success or false otherwise.
+ */
 bool reserve_try_alloc(size_t size)
 {
@@ -53 +62 @@
                 reserve -= size;
                 reserved = true;
+        } else {
+                /*
+                 * Some reservable frames may be cached by the slab allocator.
+                 * Try to reclaim some reservable memory. Try to be gentle for
+                 * the first time. If it does not help, try to reclaim
+                 * everything.
+                 */
+                irq_spinlock_unlock(&reserve_lock, true);
+                slab_reclaim(0);
+                irq_spinlock_lock(&reserve_lock, true);
+                if (reserve >= 0 && (size_t) reserve >= size) {
+                        reserve -= size;
+                        reserved = true;
+                } else {
+                        irq_spinlock_unlock(&reserve_lock, true);
+                        slab_reclaim(SLAB_RECLAIM_ALL);
+                        irq_spinlock_lock(&reserve_lock, true);
+                        if (reserve >= 0 && (size_t) reserve >= size) {
+                                reserve -= size;
+                                reserved = true;
+                        }
+                }
         }
         irq_spinlock_unlock(&reserve_lock, true);
@@ -59 +90 @@
 }
 
+/** Reserve memory.
+ *
+ * This function simply marks the respective amount of memory frames reserved.
+ * It does not implement any sort of blocking for the case there is not enough
+ * reservable memory. It will simply take the reserve into negative numbers and
+ * leave the blocking up to the allocation phase.
+ *
+ * @param size          Number of frames to reserve.
+ */
 void reserve_force_alloc(size_t size)
 {
@@ -66 +106 @@
 }
 
+/** Unreserve memory.
+ *
+ * @param size          Number of frames to unreserve.
+ */
 void reserve_free(size_t size)
 {