Changes in kernel/generic/src/sysinfo/stats.c [9efff92:6e121b8] in mainline

File:

• kernel/generic/src/sysinfo/stats.c (modified) (11 diffs)

kernel/generic/src/sysinfo/stats.c

@@ -38 +38 @@
 #include <sysinfo/stats.h>
 #include <sysinfo/sysinfo.h>
+#include <synch/spinlock.h>
+#include <synch/mutex.h>
 #include <time/clock.h>
 #include <mm/frame.h>
@@ -68 +70 @@
 static load_t avenrdy[LOAD_STEPS] = {0, 0, 0};
 
-/** Load calculation spinlock */
-SPINLOCK_STATIC_INITIALIZE_NAME(load_lock, "load_lock");
+/** Load calculation lock */
+static mutex_t load_lock;
 
 /** Get system uptime
@@ -156 +158 @@
 static size_t get_task_virtmem(as_t *as)
 {
-        mutex_lock(&as->lock);
-        
         size_t result = 0;
+
+        /*
+         * We are holding some spinlocks here and therefore are not allowed to
+         * block. Only attempt to lock the address space and address space area
+         * mutexes conditionally. If it is not possible to lock either object,
+         * allow the statistics to be inexact by skipping the respective object.
+         *
+         * Note that it may be infinitely better to let the address space
+         * management code compute these statistics as it proceeds instead of
+         * having them calculated here over and over again here.
+         */
+
+        if (SYNCH_FAILED(mutex_trylock(&as->lock)))
+                return result * PAGE_SIZE;
         
         /* Walk the B+ tree and count pages */
@@ -171 +185 @@
                         as_area_t *area = node->value[i];
                         
-                        mutex_lock(&area->lock);
+                        if (SYNCH_FAILED(mutex_trylock(&area->lock)))
+                                continue;
                         result += area->pages;
                         mutex_unlock(&area->lock);
@@ -331 +346 @@
         
         /* Interrupts are already disabled */
-        spinlock_lock(&(thread->lock));
+        spinlock_lock(&thread->lock);
         
         /* Record the statistics and increment the iterator */
@@ -337 +352 @@
         (*iterator)++;
         
-        spinlock_unlock(&(thread->lock));
+        spinlock_unlock(&thread->lock);
         
         return true;
@@ -602 +617 @@
         }
         
-        /* To always get consistent values acquire the spinlock */
-        ipl_t ipl = interrupts_disable();
-        spinlock_lock(&load_lock);
+        /* To always get consistent values acquire the mutex */
+        mutex_lock(&load_lock);
         
         unsigned int i;
@@ -610 +624 @@
                 stats_load[i] = avenrdy[i] << LOAD_FIXED_SHIFT;
         
-        spinlock_unlock(&load_lock);
-        interrupts_restore(ipl);
+        mutex_unlock(&load_lock);
         
         return ((void *) stats_load);
@@ -642 +655 @@
                 
                 /* Mutually exclude with get_stats_load() */
-                ipl_t ipl = interrupts_disable();
-                spinlock_lock(&load_lock);
+                mutex_lock(&load_lock);
                 
                 unsigned int i;
@@ -649 +661 @@
                         avenrdy[i] = load_calc(avenrdy[i], load_exp[i], ready);
                 
-                spinlock_unlock(&load_lock);
-                interrupts_restore(ipl);
+                mutex_unlock(&load_lock);
                 
                 thread_sleep(LOAD_INTERVAL);
@@ -661 +672 @@
 void stats_init(void)
 {
+        mutex_initialize(&load_lock, MUTEX_PASSIVE);
+
         sysinfo_set_item_fn_val("system.uptime", NULL, get_stats_uptime);
         sysinfo_set_item_fn_data("system.cpus", NULL, get_stats_cpus);