ddt: split internal DDT API into separate header

[mirror_zfs.git] / module / zfs / multilist.c

diff --git a/module/zfs/multilist.c b/module/zfs/multilist.c
index 73cf8cbbc21e505ab6dc6df5fc1368ca68c61721..b1cdf1c5c5f4ea7e30093811321a46b4edfc2b2f 100644 (file)
--- a/module/zfs/multilist.c
+++ b/module/zfs/multilist.c
@@ -18,27 +18,26 @@
 
 #include <sys/zfs_context.h>
 #include <sys/multilist.h>
-#include <sys/trace_defs.h>
-
-/* needed for spa_get_random() */
-#include <sys/spa.h>
+#include <sys/trace_zfs.h>
 
 /*
  * This overrides the number of sublists in each multilist_t, which defaults
  * to the number of CPUs in the system (see multilist_create()).
  */
-int zfs_multilist_num_sublists = 0;
+uint_t zfs_multilist_num_sublists = 0;
 
 /*
  * Given the object contained on the list, return a pointer to the
  * object's multilist_node_t structure it contains.
  */
-#ifdef DEBUG
+#ifdef ZFS_DEBUG
 static multilist_node_t *
 multilist_d2l(multilist_t *ml, void *obj)
 {
        return ((multilist_node_t *)((char *)obj + ml->ml_offset));
 }
+#else
+#define        multilist_d2l(ml, obj) ((void) sizeof (ml), (void) sizeof (obj), NULL)
 #endif
 
 /*
@@ -68,16 +67,15 @@ multilist_d2l(multilist_t *ml, void *obj)
  *     requirement, but a general rule of thumb in order to garner the
  *     best multi-threaded performance out of the data structure.
  */
-static multilist_t *
-multilist_create_impl(size_t size, size_t offset,
-    unsigned int num, multilist_sublist_index_func_t *index_func)
+static void
+multilist_create_impl(multilist_t *ml, size_t size, size_t offset,
+    uint_t num, multilist_sublist_index_func_t *index_func)
 {
        ASSERT3U(size, >, 0);
        ASSERT3U(size, >=, offset + sizeof (multilist_node_t));
        ASSERT3U(num, >, 0);
        ASSERT3P(index_func, !=, NULL);
 
-       multilist_t *ml = kmem_alloc(sizeof (*ml), KM_SLEEP);
        ml->ml_offset = offset;
        ml->ml_num_sublists = num;
        ml->ml_index_func = index_func;
@@ -92,19 +90,21 @@ multilist_create_impl(size_t size, size_t offset,
                mutex_init(&mls->mls_lock, NULL, MUTEX_NOLOCKDEP, NULL);
                list_create(&mls->mls_list, size, offset);
        }
-       return (ml);
 }
 
 /*
- * Allocate a new multilist, using the default number of sublists
- * (the number of CPUs, or at least 4, or the tunable
- * zfs_multilist_num_sublists).
+ * Allocate a new multilist, using the default number of sublists (the number
+ * of CPUs, or at least 4, or the tunable zfs_multilist_num_sublists). Note
+ * that the multilists do not expand if more CPUs are hot-added. In that case,
+ * we will have less fanout than boot_ncpus, but we don't want to always
+ * reserve the RAM necessary to create the extra slots for additional CPUs up
+ * front, and dynamically adding them is a complex task.
  */
-multilist_t *
-multilist_create(size_t size, size_t offset,
+void
+multilist_create(multilist_t *ml, size_t size, size_t offset,
     multilist_sublist_index_func_t *index_func)
 {
-       int num_sublists;
+       uint_t num_sublists;
 
        if (zfs_multilist_num_sublists > 0) {
                num_sublists = zfs_multilist_num_sublists;
@@ -112,7 +112,7 @@ multilist_create(size_t size, size_t offset,
                num_sublists = MAX(boot_ncpus, 4);
        }
 
-       return (multilist_create_impl(size, offset, num_sublists, index_func));
+       multilist_create_impl(ml, size, offset, num_sublists, index_func);
 }
 
 /*
@@ -138,7 +138,7 @@ multilist_destroy(multilist_t *ml)
 
        ml->ml_num_sublists = 0;
        ml->ml_offset = 0;
-       kmem_free(ml, sizeof (multilist_t));
+       ml->ml_sublists = NULL;
 }
 
 /*
@@ -274,7 +274,7 @@ multilist_get_num_sublists(multilist_t *ml)
 unsigned int
 multilist_get_random_index(multilist_t *ml)
 {
-       return (spa_get_random(ml->ml_num_sublists));
+       return (random_in_range(ml->ml_num_sublists));
 }
 
 /* Lock and return the sublist specified at the given index */
@@ -425,7 +425,5 @@ multilist_link_active(multilist_node_t *link)
        return (list_link_active(link));
 }
 
-/* BEGIN CSTYLED */
-ZFS_MODULE_PARAM(zfs, zfs_, multilist_num_sublists, INT, ZMOD_RW,
+ZFS_MODULE_PARAM(zfs, zfs_, multilist_num_sublists, UINT, ZMOD_RW,
        "Number of sublists used in each multilist");
-/* END CSTYLED */