Changeset 1a1744e in mainline

Timestamp:

2008-06-23T18:49:45Z (16 years ago)

Author:

Jakub Jermar <jakub@…>

Branches:

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

Children:

1bb3766

Parents:

08a19ba

Message:

Get rid of the infamous "Sleep not implemented" panic during low memory
condition. Use a condition variable to implement the sleep. As of now, the
condition is rather coarse and can cause that threads may sleep unnecessarily.
Needs to be fine tuned and based on the amount of memory available.

File:

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

kernel/generic/src/mm/frame.c

@@ -59 +59 @@
 #include <adt/list.h>
 #include <synch/spinlock.h>
+#include <synch/mutex.h>
+#include <synch/condvar.h>
 #include <arch/asm.h>
 #include <arch.h>
@@ -104 +106 @@
 static zones_t zones;
 
+/*
+ * Synchronization primitives used to sleep when there is no memory
+ * available.
+ */
+mutex_t zones_mtx;
+condvar_t zones_cv;
+int new_freed_mem = false;
 
 /********************/
@@ -992 +1001 @@
         if (!zone) {
                 /*
-                 * TODO: Sleep until frames are available again.
+                 * Sleep until some frames are available again.
                  */
+                if (flags & FRAME_ATOMIC) {
+                        interrupts_restore(ipl);
+                        return 0;
+                }
+                
+#ifdef CONFIG_DEBUG
+                printf("Thread %" PRIu64 " falling asleep, low memory.\n", THREAD->tid);
+#endif
+
+                mutex_lock(&zones_mtx);
+                if (!new_freed_mem)
+                        condvar_wait(&zones_cv, &zones_mtx);
+                new_freed_mem = false;
+                mutex_unlock(&zones_mtx);
+
+#ifdef CONFIG_DEBUG
+                printf("Thread %" PRIu64 " woken up, memory available.\n", THREAD->tid);
+#endif
+
                 interrupts_restore(ipl);
-
-                if (flags & FRAME_ATOMIC)
-                        return 0;
-                
-                panic("Sleep not implemented.\n");
                 goto loop;
         }
@@ -1029 +1052 @@
 
         ipl = interrupts_disable();
-        
+
         /*
          * First, find host frame zone for addr.
          */
-        zone = find_zone_and_lock(pfn,NULL);
+        zone = find_zone_and_lock(pfn, NULL);
         ASSERT(zone);
         
-        zone_frame_free(zone, pfn-zone->base);
+        zone_frame_free(zone, pfn - zone->base);
         
         spinlock_unlock(&zone->lock);
+        
+        /*
+         * Signal that some memory has been freed.
+         */
+        mutex_lock(&zones_mtx); 
+        new_freed_mem = true;
+        condvar_broadcast(&zones_cv);
+        mutex_unlock(&zones_mtx);
+
         interrupts_restore(ipl);
 }
@@ -1117 +1149 @@
                 frame_mark_unavailable(0, 1);
         }
+
+        mutex_initialize(&zones_mtx, MUTEX_ACTIVE);     /* mimic spinlock */
+        condvar_initialize(&zones_cv);
 }