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authorChris Wilson <chris@chris-wilson.co.uk>2016-05-20 16:57:38 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2016-05-20 17:58:30 -0700
commit80c4bd7a5e4368b680e0aeb57050a1b06eb573d8 (patch)
tree248bfb6e975a03f0a164e38de844f48053980158
parentf705ac4b39f30a6a5f8411a42114758f4d4655bc (diff)
mm/vmalloc: keep a separate lazy-free list
When mixing lots of vmallocs and set_memory_*() (which calls vm_unmap_aliases()) I encountered situations where the performance degraded severely due to the walking of the entire vmap_area list each invocation. One simple improvement is to add the lazily freed vmap_area to a separate lockless free list, such that we then avoid having to walk the full list on each purge. Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk> Reviewed-by: Roman Pen <r.peniaev@gmail.com> Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com> Cc: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com> Cc: Daniel Vetter <daniel.vetter@ffwll.ch> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Roman Pen <r.peniaev@gmail.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Toshi Kani <toshi.kani@hp.com> Cc: Shawn Lin <shawn.lin@rock-chips.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--include/linux/vmalloc.h3
-rw-r--r--mm/vmalloc.c39
2 files changed, 21 insertions, 21 deletions
diff --git a/include/linux/vmalloc.h b/include/linux/vmalloc.h
index d1f1d338af20..957adb741b6f 100644
--- a/include/linux/vmalloc.h
+++ b/include/linux/vmalloc.h
@@ -4,6 +4,7 @@
#include <linux/spinlock.h>
#include <linux/init.h>
#include <linux/list.h>
+#include <linux/llist.h>
#include <asm/page.h> /* pgprot_t */
#include <linux/rbtree.h>
@@ -44,7 +45,7 @@ struct vmap_area {
unsigned long flags;
struct rb_node rb_node; /* address sorted rbtree */
struct list_head list; /* address sorted list */
- struct list_head purge_list; /* "lazy purge" list */
+ struct llist_node purge_list; /* "lazy purge" list */
struct vm_struct *vm;
struct rcu_head rcu_head;
};
diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index ae7d20b447ff..6e3291882739 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -274,13 +274,12 @@ EXPORT_SYMBOL(vmalloc_to_pfn);
/*** Global kva allocator ***/
-#define VM_LAZY_FREE 0x01
-#define VM_LAZY_FREEING 0x02
#define VM_VM_AREA 0x04
static DEFINE_SPINLOCK(vmap_area_lock);
/* Export for kexec only */
LIST_HEAD(vmap_area_list);
+static LLIST_HEAD(vmap_purge_list);
static struct rb_root vmap_area_root = RB_ROOT;
/* The vmap cache globals are protected by vmap_area_lock */
@@ -601,7 +600,7 @@ static void __purge_vmap_area_lazy(unsigned long *start, unsigned long *end,
int sync, int force_flush)
{
static DEFINE_SPINLOCK(purge_lock);
- LIST_HEAD(valist);
+ struct llist_node *valist;
struct vmap_area *va;
struct vmap_area *n_va;
int nr = 0;
@@ -620,20 +619,14 @@ static void __purge_vmap_area_lazy(unsigned long *start, unsigned long *end,
if (sync)
purge_fragmented_blocks_allcpus();
- rcu_read_lock();
- list_for_each_entry_rcu(va, &vmap_area_list, list) {
- if (va->flags & VM_LAZY_FREE) {
- if (va->va_start < *start)
- *start = va->va_start;
- if (va->va_end > *end)
- *end = va->va_end;
- nr += (va->va_end - va->va_start) >> PAGE_SHIFT;
- list_add_tail(&va->purge_list, &valist);
- va->flags |= VM_LAZY_FREEING;
- va->flags &= ~VM_LAZY_FREE;
- }
+ valist = llist_del_all(&vmap_purge_list);
+ llist_for_each_entry(va, valist, purge_list) {
+ if (va->va_start < *start)
+ *start = va->va_start;
+ if (va->va_end > *end)
+ *end = va->va_end;
+ nr += (va->va_end - va->va_start) >> PAGE_SHIFT;
}
- rcu_read_unlock();
if (nr)
atomic_sub(nr, &vmap_lazy_nr);
@@ -643,7 +636,7 @@ static void __purge_vmap_area_lazy(unsigned long *start, unsigned long *end,
if (nr) {
spin_lock(&vmap_area_lock);
- list_for_each_entry_safe(va, n_va, &valist, purge_list)
+ llist_for_each_entry_safe(va, n_va, valist, purge_list)
__free_vmap_area(va);
spin_unlock(&vmap_area_lock);
}
@@ -678,9 +671,15 @@ static void purge_vmap_area_lazy(void)
*/
static void free_vmap_area_noflush(struct vmap_area *va)
{
- va->flags |= VM_LAZY_FREE;
- atomic_add((va->va_end - va->va_start) >> PAGE_SHIFT, &vmap_lazy_nr);
- if (unlikely(atomic_read(&vmap_lazy_nr) > lazy_max_pages()))
+ int nr_lazy;
+
+ nr_lazy = atomic_add_return((va->va_end - va->va_start) >> PAGE_SHIFT,
+ &vmap_lazy_nr);
+
+ /* After this point, we may free va at any time */
+ llist_add(&va->purge_list, &vmap_purge_list);
+
+ if (unlikely(nr_lazy > lazy_max_pages()))
try_purge_vmap_area_lazy();
}