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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>
hifive-unleashed-5.1
Chris Wilson 2016-05-20 16:57:38 -07:00 committed by Linus Torvalds
parent f705ac4b39
commit 80c4bd7a5e
2 changed files with 21 additions and 21 deletions
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3
include/linux/vmalloc.h
View File

@ -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;
};

39
mm/vmalloc.c
View File

@ -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();
}