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hugetlb: balance freeing of huge pages across nodes 

Free huges pages from nodes in round robin fashion in an attempt to keep
[persistent a.k.a static] hugepages balanced across nodes

New function free_pool_huge_page() is modeled on and performs roughly the
inverse of alloc_fresh_huge_page().  Replaces dequeue_huge_page() which
now has no callers, so this patch removes it.

Helper function hstate_next_node_to_free() uses new hstate member
next_to_free_nid to distribute "frees" across all nodes with huge pages.

Acked-by: David Rientjes <rientjes@google.com>
Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com>
Acked-by: Mel Gorman <mel@csn.ul.ie>
Cc: Nishanth Aravamudan <nacc@us.ibm.com>
Cc: Adam Litke <agl@us.ibm.com>
Cc: Andy Whitcroft <apw@canonical.com>
Cc: Eric Whitney <eric.whitney@hp.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Lee Schermerhorn 2009-09-21 17:01:22 -07:00 committed by Linus Torvalds
parent 55a4462af5
commit e8c5c82498
2 changed files with 88 additions and 47 deletions
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3
include/linux/hugetlb.h
View File

@ -185,7 +185,8 @@ unsigned long hugetlb_get_unmapped_area(struct file *file, unsigned long addr,
#define HSTATE_NAME_LEN 32
/* Defines one hugetlb page size */
struct hstate {
int hugetlb_next_nid;
int next_nid_to_alloc;
int next_nid_to_free;
unsigned int order;
unsigned long mask;
unsigned long max_huge_pages;

132
mm/hugetlb.c
View File

@ -456,24 +456,6 @@ static void enqueue_huge_page(struct hstate *h, struct page *page)
h->free_huge_pages_node[nid]++;
}
static struct page *dequeue_huge_page(struct hstate *h)
{
int nid;
struct page *page = NULL;
for (nid = 0; nid < MAX_NUMNODES; ++nid) {
if (!list_empty(&h->hugepage_freelists[nid])) {
page = list_entry(h->hugepage_freelists[nid].next,
struct page, lru);
list_del(&page->lru);
h->free_huge_pages--;
h->free_huge_pages_node[nid]--;
break;
}
}
return page;
}
static struct page *dequeue_huge_page_vma(struct hstate *h,
struct vm_area_struct *vma,
unsigned long address, int avoid_reserve)
@ -641,7 +623,7 @@ static struct page *alloc_fresh_huge_page_node(struct hstate *h, int nid)
/*
* Use a helper variable to find the next node and then
* copy it back to hugetlb_next_nid afterwards:
* copy it back to next_nid_to_alloc afterwards:
* otherwise there's a window in which a racer might
* pass invalid nid MAX_NUMNODES to alloc_pages_exact_node.
* But we don't need to use a spin_lock here: it really
@ -650,13 +632,13 @@ static struct page *alloc_fresh_huge_page_node(struct hstate *h, int nid)
* if we just successfully allocated a hugepage so that
* the next caller gets hugepages on the next node.
*/
static int hstate_next_node(struct hstate *h)
static int hstate_next_node_to_alloc(struct hstate *h)
{
int next_nid;
next_nid = next_node(h->hugetlb_next_nid, node_online_map);
next_nid = next_node(h->next_nid_to_alloc, node_online_map);
if (next_nid == MAX_NUMNODES)
next_nid = first_node(node_online_map);
h->hugetlb_next_nid = next_nid;
h->next_nid_to_alloc = next_nid;
return next_nid;
}
@ -667,14 +649,15 @@ static int alloc_fresh_huge_page(struct hstate *h)
int next_nid;
int ret = 0;
start_nid = h->hugetlb_next_nid;
start_nid = h->next_nid_to_alloc;
next_nid = start_nid;
do {
page = alloc_fresh_huge_page_node(h, h->hugetlb_next_nid);
page = alloc_fresh_huge_page_node(h, next_nid);
if (page)
ret = 1;
next_nid = hstate_next_node(h);
} while (!page && h->hugetlb_next_nid != start_nid);
next_nid = hstate_next_node_to_alloc(h);
} while (!page && next_nid != start_nid);
if (ret)
count_vm_event(HTLB_BUDDY_PGALLOC);
@ -684,6 +667,52 @@ static int alloc_fresh_huge_page(struct hstate *h)
return ret;
}
/*
* helper for free_pool_huge_page() - find next node
* from which to free a huge page
*/
static int hstate_next_node_to_free(struct hstate *h)
{
int next_nid;
next_nid = next_node(h->next_nid_to_free, node_online_map);
if (next_nid == MAX_NUMNODES)
next_nid = first_node(node_online_map);
h->next_nid_to_free = next_nid;
return next_nid;
}
/*
* Free huge page from pool from next node to free.
* Attempt to keep persistent huge pages more or less
* balanced over allowed nodes.
* Called with hugetlb_lock locked.
*/
static int free_pool_huge_page(struct hstate *h)
{
int start_nid;
int next_nid;
int ret = 0;
start_nid = h->next_nid_to_free;
next_nid = start_nid;
do {
if (!list_empty(&h->hugepage_freelists[next_nid])) {
struct page *page =
list_entry(h->hugepage_freelists[next_nid].next,
struct page, lru);
list_del(&page->lru);
h->free_huge_pages--;
h->free_huge_pages_node[next_nid]--;
update_and_free_page(h, page);
ret = 1;
}
next_nid = hstate_next_node_to_free(h);
} while (!ret && next_nid != start_nid);
return ret;
}
static struct page *alloc_buddy_huge_page(struct hstate *h,
struct vm_area_struct *vma, unsigned long address)
{
@ -1008,7 +1037,7 @@ int __weak alloc_bootmem_huge_page(struct hstate *h)
void *addr;
addr = __alloc_bootmem_node_nopanic(
NODE_DATA(h->hugetlb_next_nid),
NODE_DATA(h->next_nid_to_alloc),
huge_page_size(h), huge_page_size(h), 0);
if (addr) {
@ -1020,7 +1049,7 @@ int __weak alloc_bootmem_huge_page(struct hstate *h)
m = addr;
goto found;
}
hstate_next_node(h);
hstate_next_node_to_alloc(h);
nr_nodes--;
}
return 0;
@ -1141,31 +1170,43 @@ static inline void try_to_free_low(struct hstate *h, unsigned long count)
*/
static int adjust_pool_surplus(struct hstate *h, int delta)
{
static int prev_nid;
int nid = prev_nid;
int start_nid, next_nid;
int ret = 0;
VM_BUG_ON(delta != -1 && delta != 1);
do {
nid = next_node(nid, node_online_map);
if (nid == MAX_NUMNODES)
nid = first_node(node_online_map);
/* To shrink on this node, there must be a surplus page */
if (delta < 0 && !h->surplus_huge_pages_node[nid])
continue;
/* Surplus cannot exceed the total number of pages */
if (delta > 0 && h->surplus_huge_pages_node[nid] >=
if (delta < 0)
start_nid = h->next_nid_to_alloc;
else
start_nid = h->next_nid_to_free;
next_nid = start_nid;
do {
int nid = next_nid;
if (delta < 0) {
next_nid = hstate_next_node_to_alloc(h);
/*
* To shrink on this node, there must be a surplus page
*/
if (!h->surplus_huge_pages_node[nid])
continue;
}
if (delta > 0) {
next_nid = hstate_next_node_to_free(h);
/*
* Surplus cannot exceed the total number of pages
*/
if (h->surplus_huge_pages_node[nid] >=
h->nr_huge_pages_node[nid])
continue;
continue;
}
h->surplus_huge_pages += delta;
h->surplus_huge_pages_node[nid] += delta;
ret = 1;
break;
} while (nid != prev_nid);
} while (next_nid != start_nid);
prev_nid = nid;
return ret;
}
@ -1227,10 +1268,8 @@ static unsigned long set_max_huge_pages(struct hstate *h, unsigned long count)
min_count = max(count, min_count);
try_to_free_low(h, min_count);
while (min_count < persistent_huge_pages(h)) {
struct page *page = dequeue_huge_page(h);
if (!page)
if (!free_pool_huge_page(h))
break;
update_and_free_page(h, page);
}
while (count < persistent_huge_pages(h)) {
if (!adjust_pool_surplus(h, 1))
@ -1442,7 +1481,8 @@ void __init hugetlb_add_hstate(unsigned order)
h->free_huge_pages = 0;
for (i = 0; i < MAX_NUMNODES; ++i)
INIT_LIST_HEAD(&h->hugepage_freelists[i]);
h->hugetlb_next_nid = first_node(node_online_map);
h->next_nid_to_alloc = first_node(node_online_map);
h->next_nid_to_free = first_node(node_online_map);
snprintf(h->name, HSTATE_NAME_LEN, "hugepages-%lukB",
huge_page_size(h)/1024);