Messages in this thread | | | Date | Fri, 29 Oct 2010 11:55:10 +0800 | Subject | Re: [RFC][PATCH 3/3] a big contig memory allocator | From | Bob Liu <> |
| |
On Tue, Oct 26, 2010 at 6:08 PM, KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> wrote: > From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> > > Add an function to allocate contiguous memory larger than MAX_ORDER. > The main difference between usual page allocator is that this uses > memory offline technique (Isolate pages and migrate remaining pages.). > > I think this is not 100% solution because we can't avoid fragmentation, > but we have kernelcore= boot option and can create MOVABLE zone. That > helps us to allow allocate a contiguous range on demand. > > The new function is > > alloc_contig_pages(base, end, nr_pages, alignment) > > This function will allocate contiguous pages of nr_pages from the range > [base, end). If [base, end) is bigger than nr_pages, some pfn which > meats alignment will be allocated. If alignment is smaller than MAX_ORDER, > it will be raised to be MAX_ORDER. > > __alloc_contig_pages() has much more arguments. > > Some drivers allocates contig pages by bootmem or hiding some memory > from the kernel at boot. But if contig pages are necessary only in some > situation, kernelcore= boot option and using page migration is a choice. > > Note: I'm not 100% sure __GFP_HARDWALL check is required or not.. > > > Changelog: 2010-10-26 > - support gfp_t > - support zonelist/nodemask > - support [base, end) > - support alignment > > Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> > --- > include/linux/page-isolation.h | 15 ++ > mm/page_alloc.c | 29 ++++ > mm/page_isolation.c | 239 +++++++++++++++++++++++++++++++++++++++++ > 3 files changed, 283 insertions(+) > > Index: mmotm-1024/mm/page_isolation.c > =================================================================== > --- mmotm-1024.orig/mm/page_isolation.c > +++ mmotm-1024/mm/page_isolation.c > @@ -5,6 +5,7 @@ > #include <linux/mm.h> > #include <linux/page-isolation.h> > #include <linux/pageblock-flags.h> > +#include <linux/swap.h> > #include <linux/memcontrol.h> > #include <linux/migrate.h> > #include <linux/memory_hotplug.h> > @@ -398,3 +399,241 @@ retry: > } > return 0; > } > + > +/* > + * Comparing user specified [user_start, user_end) with physical memory layout > + * [phys_start, phys_end). If no intersection of length nr_pages, return 1. > + * If there is an intersection, return 0 and fill range in [*start, *end) > + */ > +static int > +__calc_search_range(unsigned long user_start, unsigned long user_end, > + unsigned long nr_pages, > + unsigned long phys_start, unsigned long phys_end, > + unsigned long *start, unsigned long *end) > +{ > + if ((user_start >= phys_end) || (user_end <= phys_start)) > + return 1; > + if (user_start <= phys_start) { > + *start = phys_start; > + *end = min(user_end, phys_end); > + } else { > + *start = user_start; > + *end = min(user_end, phys_end); > + } > + if (*end - *start < nr_pages) > + return 1; > + return 0; > +} > + > + > +/** > + * __alloc_contig_pages - allocate a contiguous physical pages > + * @base: the lowest pfn which caller wants. > + * @end: the highest pfn which caller wants. > + * @nr_pages: the length of a chunk of pages to be allocated. > + * @align_order: alignment of start address of returned chunk in order. > + * Returned' page's order will be aligned to (1 << align_order).If smaller > + * than MAX_ORDER, it's raised to MAX_ORDER. > + * @node: allocate near memory to the node, If -1, current node is used. > + * @gfpflag: used to specify what zone the memory should be from. > + * @nodemask: allocate memory within the nodemask. > + * > + * Search a memory range [base, end) and allocates physically contiguous > + * pages. If end - base is larger than nr_pages, a chunk in [base, end) will > + * be allocated > + * > + * This returns a page of the beginning of contiguous block. At failure, NULL > + * is returned. > + * > + * Limitation: at allocation, nr_pages may be increased to be aligned to > + * MAX_ORDER before searching a range. So, even if there is a enough chunk > + * for nr_pages, it may not be able to be allocated. Extra tail pages of > + * allocated chunk is returned to buddy allocator before returning the caller. > + */ > + > +#define MIGRATION_RETRY (5) > +struct page *__alloc_contig_pages(unsigned long base, unsigned long end, > + unsigned long nr_pages, int align_order, > + int node, gfp_t gfpflag, nodemask_t *mask) > +{ > + unsigned long found, aligned_pages, start; > + struct page *ret = NULL; > + int migration_failed; > + bool no_search = false; > + unsigned long align_mask; > + struct zoneref *z; > + struct zone *zone; > + struct zonelist *zonelist; > + enum zone_type highzone_idx = gfp_zone(gfpflag); > + unsigned long zone_start, zone_end, rs, re, pos; > + > + if (node == -1) > + node = numa_node_id(); > + > + /* check unsupported flags */ > + if (gfpflag & __GFP_NORETRY) > + return NULL; > + if ((gfpflag & (__GFP_WAIT | __GFP_IO | __GFP_FS | __GFP_HARDWALL)) != > + (__GFP_WAIT | __GFP_IO | __GFP_FS | __GFP_HARDWALL)) > + return NULL; > + > + if (gfpflag & __GFP_THISNODE) > + zonelist = &NODE_DATA(node)->node_zonelists[1]; > + else > + zonelist = &NODE_DATA(node)->node_zonelists[0]; > + /* > + * Base/nr_page/end should be aligned to MAX_ORDER > + */ > + found = 0; > + > + if (align_order < MAX_ORDER) > + align_order = MAX_ORDER; > + > + align_mask = (1 << align_order) - 1; > + if (end - base == nr_pages) > + no_search = true;
no_search is not used ?
> + /* > + * We allocates MAX_ORDER aligned pages and cut tail pages later. > + */ > + aligned_pages = ALIGN(nr_pages, (1 << MAX_ORDER)); > + /* > + * If end - base == nr_pages, we can't search range. base must be > + * aligned. > + */ > + if ((end - base == nr_pages) && (base & align_mask)) > + return NULL; > + > + base = ALIGN(base, (1 << align_order)); > + if ((end <= base) || (end - base < aligned_pages)) > + return NULL; > + > + /* > + * searching contig memory range within [pos, end). > + * pos is updated at migration failure to find next chunk in zone. > + * pos is reset to the base at searching next zone. > + * (see for_each_zone_zonelist_nodemask in mmzone.h) > + * > + * Note: we cannot assume zones/nodes are in linear memory layout. > + */ > + z = first_zones_zonelist(zonelist, highzone_idx, mask, &zone); > + pos = base; > +retry: > + if (!zone) > + return NULL; > + > + zone_start = ALIGN(zone->zone_start_pfn, 1 << align_order); > + zone_end = zone->zone_start_pfn + zone->spanned_pages; > + > + /* check [pos, end) is in this zone. */ > + if ((pos >= end) || > + (__calc_search_range(pos, end, aligned_pages, > + zone_start, zone_end, &rs, &re))) { > +next_zone: > + /* go to the next zone */ > + z = next_zones_zonelist(++z, highzone_idx, mask, &zone); > + /* reset the pos */ > + pos = base; > + goto retry; > + } > + /* [pos, end) is trimmed to [rs, re) in this zone. */ > + pos = rs; > + > + found = find_contig_block(rs, re, aligned_pages, align_order, zone); > + if (!found) > + goto next_zone; > + > + /* > + * OK, here, we have contiguous pageblock marked as "isolated" > + * try migration. > + */ > + drain_all_pages(); > + lru_add_drain_all(); > + > + /* > + * scan_lru_pages() finds the next PG_lru page in the range > + * scan_lru_pages() returns 0 when it reaches the end. > + */ > + migration_failed = 0; > + rs = found; > + re = found + aligned_pages; > + for (rs = scan_lru_pages(rs, re); > + rs && rs < re; > + rs = scan_lru_pages(rs, re)) { > + if (do_migrate_range(rs, re)) { > + /* it's better to try another block ? */ > + if (++migration_failed >= MIGRATION_RETRY) > + break; > + /* take a rest and synchronize LRU etc. */ > + drain_all_pages(); > + lru_add_drain_all(); > + } else /* reset migration_failure counter */ > + migration_failed = 0; > + } > + > + if (!migration_failed) { > + drain_all_pages(); > + lru_add_drain_all(); > + } > + /* Check all pages are isolated */ > + if (test_pages_isolated(found, found + aligned_pages)) { > + undo_isolate_page_range(found, aligned_pages); > + /* > + * We failed at [found...found+aligned_pages) migration. > + * "rs" is the last pfn scan_lru_pages() found that the page > + * is LRU page. Update pos and try next chunk. > + */ > + pos = ALIGN(rs + 1, (1 << align_order)); > + goto retry; /* goto next chunk */ > + } > + /* > + * OK, here, [found...found+pages) memory are isolated. > + * All pages in the range will be moved into the list with > + * page_count(page)=1. > + */ > + ret = pfn_to_page(found); > + alloc_contig_freed_pages(found, found + aligned_pages, gfpflag); > + /* unset ISOLATE */ > + undo_isolate_page_range(found, aligned_pages); > + /* Free unnecessary pages in tail */ > + for (start = found + nr_pages; start < found + aligned_pages; start++) > + __free_page(pfn_to_page(start)); > + return ret; > + > +} > +EXPORT_SYMBOL_GPL(__alloc_contig_pages); > + > +void free_contig_pages(struct page *page, int nr_pages) > +{ > + int i; > + for (i = 0; i < nr_pages; i++) > + __free_page(page + i); > +} > +EXPORT_SYMBOL_GPL(free_contig_pages); > + > +/* > + * Allocated pages will not be MOVABLE but MOVABLE zone is a suitable > + * for allocating big chunk. So, using ZONE_MOVABLE is a default. > + */ > + > +struct page *alloc_contig_pages(unsigned long base, unsigned long end, > + unsigned long nr_pages, int align_order) > +{ > + return __alloc_contig_pages(base, end, nr_pages, align_order, -1, > + GFP_KERNEL | __GFP_MOVABLE, NULL); > +} > +EXPORT_SYMBOL_GPL(alloc_contig_pages); > + > +struct page *alloc_contig_pages_host(unsigned long nr_pages, int align_order) > +{ > + return __alloc_contig_pages(0, max_pfn, nr_pages, align_order, -1, > + GFP_KERNEL | __GFP_MOVABLE, NULL); > +} > +EXPORT_SYMBOL_GPL(alloc_contig_pages_host); > + > +struct page *alloc_contig_pages_node(int nid, unsigned long nr_pages, > + int align_order) > +{ > + return __alloc_contig_pages(0, max_pfn, nr_pages, align_order, nid, > + GFP_KERNEL | __GFP_THISNODE | __GFP_MOVABLE, NULL); > +} > +EXPORT_SYMBOL_GPL(alloc_contig_pages_node); > Index: mmotm-1024/include/linux/page-isolation.h > =================================================================== > --- mmotm-1024.orig/include/linux/page-isolation.h > +++ mmotm-1024/include/linux/page-isolation.h > @@ -32,6 +32,8 @@ test_pages_isolated(unsigned long start_ > */ > extern int set_migratetype_isolate(struct page *page); > extern void unset_migratetype_isolate(struct page *page); > +extern void alloc_contig_freed_pages(unsigned long pfn, > + unsigned long pages, gfp_t flag); > > /* > * For migration. > @@ -41,4 +43,17 @@ int test_pages_in_a_zone(unsigned long s > unsigned long scan_lru_pages(unsigned long start, unsigned long end); > int do_migrate_range(unsigned long start_pfn, unsigned long end_pfn); > > +/* > + * For large alloc. > + */ > +struct page *__alloc_contig_pages(unsigned long base, unsigned long end, > + unsigned long nr_pages, int align_order, > + int node, gfp_t flag, nodemask_t *mask); > +struct page *alloc_contig_pages(unsigned long base, unsigned long end, > + unsigned long nr_pages, int align_order); > +struct page *alloc_contig_pages_host(unsigned long nr_pages, int align_order); > +struct page *alloc_contig_pages_node(int nid, unsigned long nr_pages, > + int align_order); > +void free_contig_pages(struct page *page, int nr_pages); > + > #endif > Index: mmotm-1024/mm/page_alloc.c > =================================================================== > --- mmotm-1024.orig/mm/page_alloc.c > +++ mmotm-1024/mm/page_alloc.c > @@ -5430,6 +5430,35 @@ out: > spin_unlock_irqrestore(&zone->lock, flags); > } > > + > +void alloc_contig_freed_pages(unsigned long pfn, unsigned long end, gfp_t flag) > +{ > + struct page *page; > + struct zone *zone; > + int order; > + unsigned long start = pfn; > + > + zone = page_zone(pfn_to_page(pfn)); > + spin_lock_irq(&zone->lock); > + while (pfn < end) { > + VM_BUG_ON(!pfn_valid(pfn)); > + page = pfn_to_page(pfn); > + VM_BUG_ON(page_count(page)); > + VM_BUG_ON(!PageBuddy(page)); > + list_del(&page->lru); > + order = page_order(page); > + zone->free_area[order].nr_free--; > + rmv_page_order(page); > + __mod_zone_page_state(zone, NR_FREE_PAGES, -(1UL << order)); > + pfn += 1 << order; > + } > + spin_unlock_irq(&zone->lock); > + > + /*After this, pages in the range can be freed one be one */ > + for (pfn = start; pfn < end; pfn++) > + prep_new_page(pfn_to_page(pfn), 0, flag); > +} > + > #ifdef CONFIG_MEMORY_HOTREMOVE > /* > * All pages in the range must be isolated before calling this. > -- Thanks, --Bob -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |