Add function to dump a raw summary of the slab allocator state

The purpose of this function is to allow kernel code to display the state
of the slab caches in situations where the host_slab_info RPC wouldn't be
available, e.g. before a panic.

* kern/slab.c (slab_info): New function.
* kern/slab.h: Add declaration for slab_info.

2 files changed, 34 insertions, 0 deletions

diff --git a/kern/slab.c b/kern/slab.c
index 64f1fa8..2923f47 100644
--- a/kern/slab.c
+++ b/kern/slab.c
@@ -1490,6 +1490,35 @@ void kfree(vm_offset_t data, vm_size_t size)
     }
 }
 
+void slab_info(void)
+{
+    struct kmem_cache *cache;
+    vm_size_t mem_usage, mem_reclaimable;
+
+    printf("cache                  obj slab  bufs   objs   bufs "
+           "   total reclaimable\n"
+           "name                  size size /slab  usage  count "
+           "  memory      memory\n");
+
+    simple_lock(&kmem_cache_list_lock);
+
+    list_for_each_entry(&kmem_cache_list, cache, node) {
+        simple_lock(&cache->lock);
+
+        mem_usage = (cache->nr_slabs * cache->slab_size) >> 10;
+        mem_reclaimable = (cache->nr_free_slabs * cache->slab_size) >> 10;
+
+        printf("%-19s %6lu %3luk  %4lu %6lu %6lu %7luk %10luk\n",
+               cache->name, cache->obj_size, cache->slab_size >> 10,
+               cache->bufs_per_slab, cache->nr_objs, cache->nr_bufs,
+               mem_usage, mem_reclaimable);
+
+        simple_unlock(&cache->lock);
+    }
+
+    simple_unlock(&kmem_cache_list_lock);
+}
+
 #if MACH_DEBUG
 kern_return_t host_slab_info(host_t host, cache_info_array_t *infop,
                              unsigned int *infoCntp)
diff --git a/kern/slab.h b/kern/slab.h
index 6abe2dc..47bef21 100644
--- a/kern/slab.h
+++ b/kern/slab.h
@@ -246,4 +246,9 @@ void slab_init(void);
  */
 void slab_collect(void);
 
+/*
+ * Display a summary of all kernel caches.
+ */
+void slab_info(void);
+
 #endif /* _KERN_SLAB_H */