diff options
| -rw-r--r-- | mm/mempolicy.c | 167 |
1 files changed, 146 insertions, 21 deletions
diff --git a/mm/mempolicy.c b/mm/mempolicy.c index 73790188b0eb..27da6d5c77ba 100644 --- a/mm/mempolicy.c +++ b/mm/mempolicy.c @@ -95,6 +95,9 @@ #define MPOL_MF_INVERT (MPOL_MF_INTERNAL << 1) /* Invert check for nodemask */ #define MPOL_MF_STATS (MPOL_MF_INTERNAL << 2) /* Gather statistics */ +/* The number of pages to migrate per call to migrate_pages() */ +#define MIGRATE_CHUNK_SIZE 256 + static kmem_cache_t *policy_cache; static kmem_cache_t *sn_cache; @@ -543,24 +546,91 @@ static void migrate_page_add(struct page *page, struct list_head *pagelist, } } -static int swap_pages(struct list_head *pagelist) +/* + * Migrate the list 'pagelist' of pages to a certain destination. + * + * Specify destination with either non-NULL vma or dest_node >= 0 + * Return the number of pages not migrated or error code + */ +static int migrate_pages_to(struct list_head *pagelist, + struct vm_area_struct *vma, int dest) { + LIST_HEAD(newlist); LIST_HEAD(moved); LIST_HEAD(failed); - int n; + int err = 0; + int nr_pages; + struct page *page; + struct list_head *p; - n = migrate_pages(pagelist, NULL, &moved, &failed); - putback_lru_pages(&failed); - putback_lru_pages(&moved); +redo: + nr_pages = 0; + list_for_each(p, pagelist) { + if (vma) + page = alloc_page_vma(GFP_HIGHUSER, vma, vma->vm_start); + else + page = alloc_pages_node(dest, GFP_HIGHUSER, 0); - return n; + if (!page) { + err = -ENOMEM; + goto out; + } + list_add(&page->lru, &newlist); + nr_pages++; + if (nr_pages > MIGRATE_CHUNK_SIZE); + break; + } + err = migrate_pages(pagelist, &newlist, &moved, &failed); + + putback_lru_pages(&moved); /* Call release pages instead ?? */ + + if (err >= 0 && list_empty(&newlist) && !list_empty(pagelist)) + goto redo; +out: + /* Return leftover allocated pages */ + while (!list_empty(&newlist)) { + page = list_entry(newlist.next, struct page, lru); + list_del(&page->lru); + __free_page(page); + } + list_splice(&failed, pagelist); + if (err < 0) + return err; + + /* Calculate number of leftover pages */ + nr_pages = 0; + list_for_each(p, pagelist) + nr_pages++; + return nr_pages; +} + +/* + * Migrate pages from one node to a target node. + * Returns error or the number of pages not migrated. + */ +int migrate_to_node(struct mm_struct *mm, int source, int dest, int flags) +{ + nodemask_t nmask; + LIST_HEAD(pagelist); + int err = 0; + + nodes_clear(nmask); + node_set(source, nmask); + + check_range(mm, mm->mmap->vm_start, TASK_SIZE, &nmask, + flags | MPOL_MF_DISCONTIG_OK, &pagelist); + + if (!list_empty(&pagelist)) { + err = migrate_pages_to(&pagelist, NULL, dest); + if (!list_empty(&pagelist)) + putback_lru_pages(&pagelist); + } + return err; } /* - * For now migrate_pages simply swaps out the pages from nodes that are in - * the source set but not in the target set. In the future, we would - * want a function that moves pages between the two nodesets in such - * a way as to preserve the physical layout as much as possible. + * Move pages between the two nodesets so as to preserve the physical + * layout as much as possible. * * Returns the number of page that could not be moved. */ @@ -568,22 +638,76 @@ int do_migrate_pages(struct mm_struct *mm, const nodemask_t *from_nodes, const nodemask_t *to_nodes, int flags) { LIST_HEAD(pagelist); - int count = 0; - nodemask_t nodes; + int busy = 0; + int err = 0; + nodemask_t tmp; - nodes_andnot(nodes, *from_nodes, *to_nodes); + down_read(&mm->mmap_sem); - down_read(&mm->mmap_sem); - check_range(mm, mm->mmap->vm_start, TASK_SIZE, &nodes, - flags | MPOL_MF_DISCONTIG_OK, &pagelist); +/* + * Find a 'source' bit set in 'tmp' whose corresponding 'dest' + * bit in 'to' is not also set in 'tmp'. Clear the found 'source' + * bit in 'tmp', and return that <source, dest> pair for migration. + * The pair of nodemasks 'to' and 'from' define the map. + * + * If no pair of bits is found that way, fallback to picking some + * pair of 'source' and 'dest' bits that are not the same. If the + * 'source' and 'dest' bits are the same, this represents a node + * that will be migrating to itself, so no pages need move. + * + * If no bits are left in 'tmp', or if all remaining bits left + * in 'tmp' correspond to the same bit in 'to', return false + * (nothing left to migrate). + * + * This lets us pick a pair of nodes to migrate between, such that + * if possible the dest node is not already occupied by some other + * source node, minimizing the risk of overloading the memory on a + * node that would happen if we migrated incoming memory to a node + * before migrating outgoing memory source that same node. + * + * A single scan of tmp is sufficient. As we go, we remember the + * most recent <s, d> pair that moved (s != d). If we find a pair + * that not only moved, but what's better, moved to an empty slot + * (d is not set in tmp), then we break out then, with that pair. + * Otherwise when we finish scannng from_tmp, we at least have the + * most recent <s, d> pair that moved. If we get all the way through + * the scan of tmp without finding any node that moved, much less + * moved to an empty node, then there is nothing left worth migrating. + */ - if (!list_empty(&pagelist)) { - count = swap_pages(&pagelist); - putback_lru_pages(&pagelist); + tmp = *from_nodes; + while (!nodes_empty(tmp)) { + int s,d; + int source = -1; + int dest = 0; + + for_each_node_mask(s, tmp) { + d = node_remap(s, *from_nodes, *to_nodes); + if (s == d) + continue; + + source = s; /* Node moved. Memorize */ + dest = d; + + /* dest not in remaining from nodes? */ + if (!node_isset(dest, tmp)) + break; + } + if (source == -1) + break; + + node_clear(source, tmp); + err = migrate_to_node(mm, source, dest, flags); + if (err > 0) + busy += err; + if (err < 0) + break; } up_read(&mm->mmap_sem); - return count; + if (err < 0) + return err; + return busy; } long do_mbind(unsigned long start, unsigned long len, @@ -643,8 +767,9 @@ long do_mbind(unsigned long start, unsigned long len, int nr_failed = 0; err = mbind_range(vma, start, end, new); + if (!list_empty(&pagelist)) - nr_failed = swap_pages(&pagelist); + nr_failed = migrate_pages_to(&pagelist, vma, -1); if (!err && nr_failed && (flags & MPOL_MF_STRICT)) err = -EIO; |
