> Date: Mon, 8 Aug 2016 21:56:23 +1000
> From: David Gwynne <[email protected]>
>
> the current tracking of free static map entries is done as hand
> rolled list manipulations using pointers in an rb_entry. it's really
> confusing to read.
>
> since its simple list manipulations, this replaces the hand rolled
> code with an SLIST.
>
> ok?
I like this. How does this change the way entries are recycled? The
new code will use the last entry that was freed. Was this the case
with the old code as well?
> Index: uvm.h
> ===================================================================
> RCS file: /cvs/src/sys/uvm/uvm.h,v
> retrieving revision 1.60
> diff -u -p -r1.60 uvm.h
> --- uvm.h 8 Oct 2015 15:58:38 -0000 1.60
> +++ uvm.h 8 Aug 2016 11:53:57 -0000
> @@ -69,7 +69,7 @@ struct uvm {
> struct mutex aiodoned_lock;
>
> /* static kernel map entry pool */
> - vm_map_entry_t kentry_free; /* free page pool */
> + SLIST_HEAD(, vm_map_entry) kentry_free; /* free page pool */
>
> /* aio_done is locked by uvm.aiodoned_lock. */
> TAILQ_HEAD(, buf) aio_done; /* done async i/o reqs */
> Index: uvm_map.c
> ===================================================================
> RCS file: /cvs/src/sys/uvm/uvm_map.c,v
> retrieving revision 1.219
> diff -u -p -r1.219 uvm_map.c
> --- uvm_map.c 30 Jul 2016 16:43:44 -0000 1.219
> +++ uvm_map.c 8 Aug 2016 11:53:57 -0000
> @@ -1669,25 +1669,23 @@ uvm_mapent_alloc(struct vm_map *map, int
>
> if (map->flags & VM_MAP_INTRSAFE || cold) {
> mtx_enter(&uvm_kmapent_mtx);
> - me = uvm.kentry_free;
> - if (me == NULL) {
> + if (SLIST_EMPTY(&uvm.kentry_free)) {
> ne = km_alloc(PAGE_SIZE, &kv_page, &kp_dirty,
> &kd_nowait);
> if (ne == NULL)
> panic("uvm_mapent_alloc: cannot allocate map "
> "entry");
> - for (i = 0;
> - i < PAGE_SIZE / sizeof(struct vm_map_entry) - 1;
> - i++)
> - RB_LEFT(&ne[i], daddrs.addr_entry) = &ne[i + 1];
> - RB_LEFT(&ne[i], daddrs.addr_entry) = NULL;
> - me = ne;
> + for (i = 0; i < PAGE_SIZE / sizeof(*ne); i++) {
> + SLIST_INSERT_HEAD(&uvm.kentry_free,
> + &ne[i], daddrs.addr_kentry);
> + }
> if (ratecheck(&uvm_kmapent_last_warn_time,
> &uvm_kmapent_warn_rate))
> printf("uvm_mapent_alloc: out of static "
> "map entries\n");
> }
> - uvm.kentry_free = RB_LEFT(me, daddrs.addr_entry);
> + me = SLIST_FIRST(&uvm.kentry_free);
> + SLIST_REMOVE_HEAD(&uvm.kentry_free, daddrs.addr_kentry);
> uvmexp.kmapent++;
> mtx_leave(&uvm_kmapent_mtx);
> me->flags = UVM_MAP_STATIC;
> @@ -1725,8 +1723,7 @@ uvm_mapent_free(struct vm_map_entry *me)
> {
> if (me->flags & UVM_MAP_STATIC) {
> mtx_enter(&uvm_kmapent_mtx);
> - RB_LEFT(me, daddrs.addr_entry) = uvm.kentry_free;
> - uvm.kentry_free = me;
> + SLIST_INSERT_HEAD(&uvm.kentry_free, me, daddrs.addr_kentry);
> uvmexp.kmapent--;
> mtx_leave(&uvm_kmapent_mtx);
> } else if (me->flags & UVM_MAP_KMEM) {
> @@ -2795,11 +2792,10 @@ uvm_map_init(void)
>
> /* now set up static pool of kernel map entries ... */
> mtx_init(&uvm_kmapent_mtx, IPL_VM);
> - uvm.kentry_free = NULL;
> + SLIST_INIT(&uvm.kentry_free);
> for (lcv = 0 ; lcv < MAX_KMAPENT ; lcv++) {
> - RB_LEFT(&kernel_map_entry[lcv], daddrs.addr_entry) =
> - uvm.kentry_free;
> - uvm.kentry_free = &kernel_map_entry[lcv];
> + SLIST_INSERT_HEAD(&uvm.kentry_free,
> + &kernel_map_entry[lcv], daddrs.addr_kentry);
> }
>
> /* initialize the map-related pools. */
> Index: uvm_map.h
> ===================================================================
> RCS file: /cvs/src/sys/uvm/uvm_map.h,v
> retrieving revision 1.55
> diff -u -p -r1.55 uvm_map.h
> --- uvm_map.h 9 Sep 2015 23:33:37 -0000 1.55
> +++ uvm_map.h 8 Aug 2016 11:53:57 -0000
> @@ -161,6 +161,7 @@ union vm_map_object {
> struct vm_map_entry {
> union {
> RB_ENTRY(vm_map_entry) addr_entry; /* address tree */
> + SLIST_ENTRY(vm_map_entry) addr_kentry;
> } daddrs;
>
> union {
>
>
