Messages in this thread Patch in this message | | | From | Mel Gorman <> | Subject | [PATCH 4/5] Light Fragmentation Avoidance V20: 004_percpu | Date | Tue, 15 Nov 2005 16:50:09 +0000 (GMT) |
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The freelists for each allocation type can slowly become corrupted due to the per-cpu list. Consider what happens when the following happens
1. A 2^(MAX_ORDER-1) list is reserved for __GFP_EASYRCLM pages 2. An order-0 page is allocated from the newly reserved block 3. The page is freed and placed on the per-cpu list 4. alloc_page() is called with GFP_KERNEL as the gfp_mask 5. The per-cpu list is used to satisfy the allocation
This results in a kernel page is in the middle of a RCLM_EASY region. This means that over long periods of the time, the anti-fragmentation scheme slowly degrades to the standard allocator.
This patch divides the per-cpu lists into RCLM_TYPES number of lists.
Signed-off-by: Mel Gorman <mel@csn.ul.ie> diff -rup -X /usr/src/patchset-0.5/bin//dontdiff linux-2.6.14-mm2-003_fragcore/include/linux/mmzone.h linux-2.6.14-mm2-004_percpu/include/linux/mmzone.h --- linux-2.6.14-mm2-003_fragcore/include/linux/mmzone.h 2005-11-15 12:43:41.000000000 +0000 +++ linux-2.6.14-mm2-004_percpu/include/linux/mmzone.h 2005-11-15 12:44:23.000000000 +0000 @@ -56,11 +56,11 @@ struct zone_padding { #endif struct per_cpu_pages { - int count; /* number of pages in the list */ + int count[RCLM_TYPES]; /* Number of pages on the lists */ int low; /* low watermark, refill needed */ int high; /* high watermark, emptying needed */ int batch; /* chunk size for buddy add/remove */ - struct list_head list; /* the list of pages */ + struct list_head list[RCLM_TYPES]; /* the lists of pages */ }; struct per_cpu_pageset { @@ -75,6 +75,9 @@ struct per_cpu_pageset { #endif } ____cacheline_aligned_in_smp; +/* Helpers for per_cpu_pages */ +#define pcp_count(pcp) (pcp.count[RCLM_NORCLM] + pcp.count[RCLM_EASY]) + #ifdef CONFIG_NUMA #define zone_pcp(__z, __cpu) ((__z)->pageset[(__cpu)]) #else diff -rup -X /usr/src/patchset-0.5/bin//dontdiff linux-2.6.14-mm2-003_fragcore/mm/page_alloc.c linux-2.6.14-mm2-004_percpu/mm/page_alloc.c --- linux-2.6.14-mm2-003_fragcore/mm/page_alloc.c 2005-11-15 12:44:27.000000000 +0000 +++ linux-2.6.14-mm2-004_percpu/mm/page_alloc.c 2005-11-15 12:44:23.000000000 +0000 @@ -623,7 +623,7 @@ static int rmqueue_bulk(struct zone *zon void drain_remote_pages(void) { struct zone *zone; - int i; + int i, pindex; unsigned long flags; local_irq_save(flags); @@ -639,9 +639,16 @@ void drain_remote_pages(void) struct per_cpu_pages *pcp; pcp = &pset->pcp[i]; - if (pcp->count) - pcp->count -= free_pages_bulk(zone, pcp->count, - &pcp->list, 0); + for_each_rclmtype(pindex) { + if (!pcp->count[pindex]) + continue; + + /* Try remove all pages from the pcpu list */ + pcp->count[pindex] -= + free_pages_bulk(zone, + pcp->count[pindex], + &pcp->list[pindex], 0); + } } } local_irq_restore(flags); @@ -652,7 +659,7 @@ void drain_remote_pages(void) static void __drain_pages(unsigned int cpu) { struct zone *zone; - int i; + int i, pindex; for_each_zone(zone) { struct per_cpu_pageset *pset; @@ -662,8 +669,16 @@ static void __drain_pages(unsigned int c struct per_cpu_pages *pcp; pcp = &pset->pcp[i]; - pcp->count -= free_pages_bulk(zone, pcp->count, - &pcp->list, 0); + for_each_rclmtype(pindex) { + if (!pcp->count[pindex]) + continue; + + /* Try remove all pages from the pcpu list */ + pcp->count[pindex] -= + free_pages_bulk(zone, + pcp->count[pindex], + &pcp->list[pindex], 0); + } } } } @@ -743,6 +758,7 @@ static void fastcall free_hot_cold_page( struct zone *zone = page_zone(page); struct per_cpu_pages *pcp; unsigned long flags; + int pindex; arch_free_page(page, 0); @@ -752,11 +768,14 @@ static void fastcall free_hot_cold_page( page->mapping = NULL; free_pages_check(__FUNCTION__, page); pcp = &zone_pcp(zone, get_cpu())->pcp[cold]; + local_irq_save(flags); - list_add(&page->lru, &pcp->list); - pcp->count++; - if (pcp->count >= pcp->high) - pcp->count -= free_pages_bulk(zone, pcp->batch, &pcp->list, 0); + pindex = get_pageblock_type(zone, page); + list_add(&page->lru, &pcp->list[pindex]); + pcp->count[pindex]++; + if (pcp->count[pindex] >= pcp->high) + pcp->count[pindex] -= free_pages_bulk(zone, pcp->batch, + &pcp->list[pindex], 0); local_irq_restore(flags); put_cpu(); } @@ -798,14 +817,16 @@ buffered_rmqueue(struct zone *zone, int pcp = &zone_pcp(zone, get_cpu())->pcp[cold]; local_irq_save(flags); - if (pcp->count <= pcp->low) - pcp->count += rmqueue_bulk(zone, 0, - pcp->batch, &pcp->list, + if (pcp->count[alloctype] <= pcp->low) + pcp->count[alloctype] += rmqueue_bulk(zone, 0, + pcp->batch, + &pcp->list[alloctype], alloctype); - if (pcp->count) { - page = list_entry(pcp->list.next, struct page, lru); + if (pcp->count[alloctype]) { + page = list_entry(pcp->list[alloctype].next, + struct page, lru); list_del(&page->lru); - pcp->count--; + pcp->count[alloctype]--; } local_irq_restore(flags); put_cpu(); @@ -847,9 +868,9 @@ int zone_watermark_ok(struct zone *z, in int o,t; if (alloc_flags & ALLOC_HIGH) - mark -= mark / 2; + mark /= 2; if (alloc_flags & ALLOC_HARDER) - mark -= mark / 4; + mark /= 4; if (free_pages <= mark + z->lowmem_reserve[classzone_idx]) goto out_failed; @@ -861,13 +882,13 @@ int zone_watermark_ok(struct zone *z, in * unavailable */ free_pages -= z->free_area_lists[t][o].nr_free << o; + } - /* Require fewer higher order pages to be free */ - min >>= 1; + /* Require fewer higher order pages to be free */ + min >>= 1; - if (free_pages <= min) - goto out_failed; - } + if (free_pages <= min) + goto out_failed; } return 1; @@ -1472,7 +1493,7 @@ void show_free_areas(void) pageset->pcp[temperature].low, pageset->pcp[temperature].high, pageset->pcp[temperature].batch, - pageset->pcp[temperature].count); + pcp_count(pageset->pcp[temperature])); } } @@ -1930,18 +1951,23 @@ inline void setup_pageset(struct per_cpu memset(p, 0, sizeof(*p)); pcp = &p->pcp[0]; /* hot */ - pcp->count = 0; + pcp->count[RCLM_NORCLM] = 0; + pcp->count[RCLM_EASY] = 0; pcp->low = 0; - pcp->high = 6 * batch; + pcp->high = 3 * batch; pcp->batch = max(1UL, 1 * batch); - INIT_LIST_HEAD(&pcp->list); + INIT_LIST_HEAD(&pcp->list[RCLM_NORCLM]); + INIT_LIST_HEAD(&pcp->list[RCLM_EASY]); pcp = &p->pcp[1]; /* cold*/ - pcp->count = 0; + + pcp->count[RCLM_NORCLM] = 0; + pcp->count[RCLM_EASY] = 0; pcp->low = 0; - pcp->high = 2 * batch; + pcp->high = batch; pcp->batch = max(1UL, batch/2); - INIT_LIST_HEAD(&pcp->list); + INIT_LIST_HEAD(&pcp->list[RCLM_NORCLM]); + INIT_LIST_HEAD(&pcp->list[RCLM_EASY]); } #ifndef CONFIG_SPARSEMEM @@ -2381,7 +2407,7 @@ static int zoneinfo_show(struct seq_file "\n high: %i" "\n batch: %i", i, j, - pageset->pcp[j].count, + pcp_count(pageset->pcp[j]), pageset->pcp[j].low, pageset->pcp[j].high, pageset->pcp[j].batch); 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