From 22b737f4c75197372d64afc6ed1bccd58c00e549 Mon Sep 17 00:00:00 2001 From: WANG Cong Date: Tue, 1 Dec 2009 23:28:10 +0900 Subject: percpu: refactor the code in pcpu_[de]populate_chunk() Using break statement at the end of a for loop is confusing, refactor it by replacing the for loop. Signed-off-by: WANG Cong Signed-off-by: Tejun Heo --- mm/percpu.c | 18 ++++++++---------- 1 file changed, 8 insertions(+), 10 deletions(-) (limited to 'mm') diff --git a/mm/percpu.c b/mm/percpu.c index e2e80fc7860..77c6f7994a4 100644 --- a/mm/percpu.c +++ b/mm/percpu.c @@ -886,11 +886,10 @@ static void pcpu_depopulate_chunk(struct pcpu_chunk *chunk, int off, int size) int rs, re; /* quick path, check whether it's empty already */ - pcpu_for_each_unpop_region(chunk, rs, re, page_start, page_end) { - if (rs == page_start && re == page_end) - return; - break; - } + rs = page_start; + pcpu_next_unpop(chunk, &rs, &re, page_end); + if (rs == page_start && re == page_end) + return; /* immutable chunks can't be depopulated */ WARN_ON(chunk->immutable); @@ -941,11 +940,10 @@ static int pcpu_populate_chunk(struct pcpu_chunk *chunk, int off, int size) int rs, re, rc; /* quick path, check whether all pages are already there */ - pcpu_for_each_pop_region(chunk, rs, re, page_start, page_end) { - if (rs == page_start && re == page_end) - goto clear; - break; - } + rs = page_start; + pcpu_next_pop(chunk, &rs, &re, page_end); + if (rs == page_start && re == page_end) + goto clear; /* need to allocate and map pages, this chunk can't be immutable */ WARN_ON(chunk->immutable); -- cgit v1.2.3 From 99dcc3e5a94ed491fbef402831d8c0bbb267f995 Mon Sep 17 00:00:00 2001 From: Christoph Lameter Date: Tue, 5 Jan 2010 15:34:51 +0900 Subject: this_cpu: Page allocator conversion Use the per cpu allocator functionality to avoid per cpu arrays in struct zone. This drastically reduces the size of struct zone for systems with large amounts of processors and allows placement of critical variables of struct zone in one cacheline even on very large systems. Another effect is that the pagesets of one processor are placed near one another. If multiple pagesets from different zones fit into one cacheline then additional cacheline fetches can be avoided on the hot paths when allocating memory from multiple zones. Bootstrap becomes simpler if we use the same scheme for UP, SMP, NUMA. #ifdefs are reduced and we can drop the zone_pcp macro. Hotplug handling is also simplified since cpu alloc can bring up and shut down cpu areas for a specific cpu as a whole. So there is no need to allocate or free individual pagesets. V7-V8: - Explain chicken egg dilemmna with percpu allocator. V4-V5: - Fix up cases where per_cpu_ptr is called before irq disable - Integrate the bootstrap logic that was separate before. tj: Build failure in pageset_cpuup_callback() due to missing ret variable fixed. Reviewed-by: Mel Gorman Signed-off-by: Christoph Lameter Signed-off-by: Tejun Heo --- mm/page_alloc.c | 202 ++++++++++++++++++++------------------------------------ mm/vmstat.c | 14 ++-- 2 files changed, 79 insertions(+), 137 deletions(-) (limited to 'mm') diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 4e9f5cc5fb5..6849e870de5 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -1008,10 +1008,10 @@ static void drain_pages(unsigned int cpu) struct per_cpu_pageset *pset; struct per_cpu_pages *pcp; - pset = zone_pcp(zone, cpu); + local_irq_save(flags); + pset = per_cpu_ptr(zone->pageset, cpu); pcp = &pset->pcp; - local_irq_save(flags); free_pcppages_bulk(zone, pcp->count, pcp); pcp->count = 0; local_irq_restore(flags); @@ -1095,7 +1095,6 @@ static void free_hot_cold_page(struct page *page, int cold) arch_free_page(page, 0); kernel_map_pages(page, 1, 0); - pcp = &zone_pcp(zone, get_cpu())->pcp; migratetype = get_pageblock_migratetype(page); set_page_private(page, migratetype); local_irq_save(flags); @@ -1118,6 +1117,7 @@ static void free_hot_cold_page(struct page *page, int cold) migratetype = MIGRATE_MOVABLE; } + pcp = &this_cpu_ptr(zone->pageset)->pcp; if (cold) list_add_tail(&page->lru, &pcp->lists[migratetype]); else @@ -1130,7 +1130,6 @@ static void free_hot_cold_page(struct page *page, int cold) out: local_irq_restore(flags); - put_cpu(); } void free_hot_page(struct page *page) @@ -1180,17 +1179,15 @@ struct page *buffered_rmqueue(struct zone *preferred_zone, unsigned long flags; struct page *page; int cold = !!(gfp_flags & __GFP_COLD); - int cpu; again: - cpu = get_cpu(); if (likely(order == 0)) { struct per_cpu_pages *pcp; struct list_head *list; - pcp = &zone_pcp(zone, cpu)->pcp; - list = &pcp->lists[migratetype]; local_irq_save(flags); + pcp = &this_cpu_ptr(zone->pageset)->pcp; + list = &pcp->lists[migratetype]; if (list_empty(list)) { pcp->count += rmqueue_bulk(zone, 0, pcp->batch, list, @@ -1231,7 +1228,6 @@ again: __count_zone_vm_events(PGALLOC, zone, 1 << order); zone_statistics(preferred_zone, zone); local_irq_restore(flags); - put_cpu(); VM_BUG_ON(bad_range(zone, page)); if (prep_new_page(page, order, gfp_flags)) @@ -1240,7 +1236,6 @@ again: failed: local_irq_restore(flags); - put_cpu(); return NULL; } @@ -2179,7 +2174,7 @@ void show_free_areas(void) for_each_online_cpu(cpu) { struct per_cpu_pageset *pageset; - pageset = zone_pcp(zone, cpu); + pageset = per_cpu_ptr(zone->pageset, cpu); printk("CPU %4d: hi:%5d, btch:%4d usd:%4d\n", cpu, pageset->pcp.high, @@ -2744,10 +2739,29 @@ static void build_zonelist_cache(pg_data_t *pgdat) #endif /* CONFIG_NUMA */ +/* + * Boot pageset table. One per cpu which is going to be used for all + * zones and all nodes. The parameters will be set in such a way + * that an item put on a list will immediately be handed over to + * the buddy list. This is safe since pageset manipulation is done + * with interrupts disabled. + * + * The boot_pagesets must be kept even after bootup is complete for + * unused processors and/or zones. They do play a role for bootstrapping + * hotplugged processors. + * + * zoneinfo_show() and maybe other functions do + * not check if the processor is online before following the pageset pointer. + * Other parts of the kernel may not check if the zone is available. + */ +static void setup_pageset(struct per_cpu_pageset *p, unsigned long batch); +static DEFINE_PER_CPU(struct per_cpu_pageset, boot_pageset); + /* return values int ....just for stop_machine() */ static int __build_all_zonelists(void *dummy) { int nid; + int cpu; #ifdef CONFIG_NUMA memset(node_load, 0, sizeof(node_load)); @@ -2758,6 +2772,23 @@ static int __build_all_zonelists(void *dummy) build_zonelists(pgdat); build_zonelist_cache(pgdat); } + + /* + * Initialize the boot_pagesets that are going to be used + * for bootstrapping processors. The real pagesets for + * each zone will be allocated later when the per cpu + * allocator is available. + * + * boot_pagesets are used also for bootstrapping offline + * cpus if the system is already booted because the pagesets + * are needed to initialize allocators on a specific cpu too. + * F.e. the percpu allocator needs the page allocator which + * needs the percpu allocator in order to allocate its pagesets + * (a chicken-egg dilemma). + */ + for_each_possible_cpu(cpu) + setup_pageset(&per_cpu(boot_pageset, cpu), 0); + return 0; } @@ -3095,121 +3126,33 @@ static void setup_pagelist_highmark(struct per_cpu_pageset *p, pcp->batch = PAGE_SHIFT * 8; } - -#ifdef CONFIG_NUMA -/* - * Boot pageset table. One per cpu which is going to be used for all - * zones and all nodes. The parameters will be set in such a way - * that an item put on a list will immediately be handed over to - * the buddy list. This is safe since pageset manipulation is done - * with interrupts disabled. - * - * Some NUMA counter updates may also be caught by the boot pagesets. - * - * The boot_pagesets must be kept even after bootup is complete for - * unused processors and/or zones. They do play a role for bootstrapping - * hotplugged processors. - * - * zoneinfo_show() and maybe other functions do - * not check if the processor is online before following the pageset pointer. - * Other parts of the kernel may not check if the zone is available. - */ -static struct per_cpu_pageset boot_pageset[NR_CPUS]; - /* - * Dynamically allocate memory for the - * per cpu pageset array in struct zone. + * Allocate per cpu pagesets and initialize them. + * Before this call only boot pagesets were available. + * Boot pagesets will no longer be used by this processorr + * after setup_per_cpu_pageset(). */ -static int __cpuinit process_zones(int cpu) +void __init setup_per_cpu_pageset(void) { - struct zone *zone, *dzone; - int node = cpu_to_node(cpu); - - node_set_state(node, N_CPU); /* this node has a cpu */ + struct zone *zone; + int cpu; for_each_populated_zone(zone) { - zone_pcp(zone, cpu) = kmalloc_node(sizeof(struct per_cpu_pageset), - GFP_KERNEL, node); - if (!zone_pcp(zone, cpu)) - goto bad; - - setup_pageset(zone_pcp(zone, cpu), zone_batchsize(zone)); - - if (percpu_pagelist_fraction) - setup_pagelist_highmark(zone_pcp(zone, cpu), - (zone->present_pages / percpu_pagelist_fraction)); - } - - return 0; -bad: - for_each_zone(dzone) { - if (!populated_zone(dzone)) - continue; - if (dzone == zone) - break; - kfree(zone_pcp(dzone, cpu)); - zone_pcp(dzone, cpu) = &boot_pageset[cpu]; - } - return -ENOMEM; -} + zone->pageset = alloc_percpu(struct per_cpu_pageset); -static inline void free_zone_pagesets(int cpu) -{ - struct zone *zone; - - for_each_zone(zone) { - struct per_cpu_pageset *pset = zone_pcp(zone, cpu); + for_each_possible_cpu(cpu) { + struct per_cpu_pageset *pcp = per_cpu_ptr(zone->pageset, cpu); - /* Free per_cpu_pageset if it is slab allocated */ - if (pset != &boot_pageset[cpu]) - kfree(pset); - zone_pcp(zone, cpu) = &boot_pageset[cpu]; - } -} + setup_pageset(pcp, zone_batchsize(zone)); -static int __cpuinit pageset_cpuup_callback(struct notifier_block *nfb, - unsigned long action, - void *hcpu) -{ - int cpu = (long)hcpu; - int ret = NOTIFY_OK; - - switch (action) { - case CPU_UP_PREPARE: - case CPU_UP_PREPARE_FROZEN: - if (process_zones(cpu)) - ret = NOTIFY_BAD; - break; - case CPU_UP_CANCELED: - case CPU_UP_CANCELED_FROZEN: - case CPU_DEAD: - case CPU_DEAD_FROZEN: - free_zone_pagesets(cpu); - break; - default: - break; + if (percpu_pagelist_fraction) + setup_pagelist_highmark(pcp, + (zone->present_pages / + percpu_pagelist_fraction)); + } } - return ret; } -static struct notifier_block __cpuinitdata pageset_notifier = - { &pageset_cpuup_callback, NULL, 0 }; - -void __init setup_per_cpu_pageset(void) -{ - int err; - - /* Initialize per_cpu_pageset for cpu 0. - * A cpuup callback will do this for every cpu - * as it comes online - */ - err = process_zones(smp_processor_id()); - BUG_ON(err); - register_cpu_notifier(&pageset_notifier); -} - -#endif - static noinline __init_refok int zone_wait_table_init(struct zone *zone, unsigned long zone_size_pages) { @@ -3263,7 +3206,7 @@ static int __zone_pcp_update(void *data) struct per_cpu_pageset *pset; struct per_cpu_pages *pcp; - pset = zone_pcp(zone, cpu); + pset = per_cpu_ptr(zone->pageset, cpu); pcp = &pset->pcp; local_irq_save(flags); @@ -3281,21 +3224,17 @@ void zone_pcp_update(struct zone *zone) static __meminit void zone_pcp_init(struct zone *zone) { - int cpu; - unsigned long batch = zone_batchsize(zone); + /* + * per cpu subsystem is not up at this point. The following code + * relies on the ability of the linker to provide the + * offset of a (static) per cpu variable into the per cpu area. + */ + zone->pageset = &boot_pageset; - for (cpu = 0; cpu < NR_CPUS; cpu++) { -#ifdef CONFIG_NUMA - /* Early boot. Slab allocator not functional yet */ - zone_pcp(zone, cpu) = &boot_pageset[cpu]; - setup_pageset(&boot_pageset[cpu],0); -#else - setup_pageset(zone_pcp(zone,cpu), batch); -#endif - } if (zone->present_pages) - printk(KERN_DEBUG " %s zone: %lu pages, LIFO batch:%lu\n", - zone->name, zone->present_pages, batch); + printk(KERN_DEBUG " %s zone: %lu pages, LIFO batch:%u\n", + zone->name, zone->present_pages, + zone_batchsize(zone)); } __meminit int init_currently_empty_zone(struct zone *zone, @@ -4809,10 +4748,11 @@ int percpu_pagelist_fraction_sysctl_handler(ctl_table *table, int write, if (!write || (ret == -EINVAL)) return ret; for_each_populated_zone(zone) { - for_each_online_cpu(cpu) { + for_each_possible_cpu(cpu) { unsigned long high; high = zone->present_pages / percpu_pagelist_fraction; - setup_pagelist_highmark(zone_pcp(zone, cpu), high); + setup_pagelist_highmark( + per_cpu_ptr(zone->pageset, cpu), high); } } return 0; diff --git a/mm/vmstat.c b/mm/vmstat.c index 6051fbab67b..1ba0bb7ad04 100644 --- a/mm/vmstat.c +++ b/mm/vmstat.c @@ -139,7 +139,8 @@ static void refresh_zone_stat_thresholds(void) threshold = calculate_threshold(zone); for_each_online_cpu(cpu) - zone_pcp(zone, cpu)->stat_threshold = threshold; + per_cpu_ptr(zone->pageset, cpu)->stat_threshold + = threshold; } } @@ -149,7 +150,8 @@ static void refresh_zone_stat_thresholds(void) void __mod_zone_page_state(struct zone *zone, enum zone_stat_item item, int delta) { - struct per_cpu_pageset *pcp = zone_pcp(zone, smp_processor_id()); + struct per_cpu_pageset *pcp = this_cpu_ptr(zone->pageset); + s8 *p = pcp->vm_stat_diff + item; long x; @@ -202,7 +204,7 @@ EXPORT_SYMBOL(mod_zone_page_state); */ void __inc_zone_state(struct zone *zone, enum zone_stat_item item) { - struct per_cpu_pageset *pcp = zone_pcp(zone, smp_processor_id()); + struct per_cpu_pageset *pcp = this_cpu_ptr(zone->pageset); s8 *p = pcp->vm_stat_diff + item; (*p)++; @@ -223,7 +225,7 @@ EXPORT_SYMBOL(__inc_zone_page_state); void __dec_zone_state(struct zone *zone, enum zone_stat_item item) { - struct per_cpu_pageset *pcp = zone_pcp(zone, smp_processor_id()); + struct per_cpu_pageset *pcp = this_cpu_ptr(zone->pageset); s8 *p = pcp->vm_stat_diff + item; (*p)--; @@ -300,7 +302,7 @@ void refresh_cpu_vm_stats(int cpu) for_each_populated_zone(zone) { struct per_cpu_pageset *p; - p = zone_pcp(zone, cpu); + p = per_cpu_ptr(zone->pageset, cpu); for (i = 0; i < NR_VM_ZONE_STAT_ITEMS; i++) if (p->vm_stat_diff[i]) { @@ -741,7 +743,7 @@ static void zoneinfo_show_print(struct seq_file *m, pg_data_t *pgdat, for_each_online_cpu(i) { struct per_cpu_pageset *pageset; - pageset = zone_pcp(zone, i); + pageset = per_cpu_ptr(zone->pageset, i); seq_printf(m, "\n cpu: %i" "\n count: %i" -- cgit v1.2.3 From ad596925eaf9a48ed61bc9210088828f1f8e0552 Mon Sep 17 00:00:00 2001 From: Christoph Lameter Date: Tue, 5 Jan 2010 15:34:51 +0900 Subject: this_cpu: Remove pageset_notifier Remove the pageset notifier since it only marks that a processor exists on a specific node. Move that code into the vmstat notifier. Signed-off-by: Christoph Lameter Signed-off-by: Tejun Heo --- mm/vmstat.c | 1 + 1 file changed, 1 insertion(+) (limited to 'mm') diff --git a/mm/vmstat.c b/mm/vmstat.c index 1ba0bb7ad04..fc5aa183bc4 100644 --- a/mm/vmstat.c +++ b/mm/vmstat.c @@ -908,6 +908,7 @@ static int __cpuinit vmstat_cpuup_callback(struct notifier_block *nfb, case CPU_ONLINE: case CPU_ONLINE_FROZEN: start_cpu_timer(cpu); + node_set_state(cpu_to_node(cpu), N_CPU); break; case CPU_DOWN_PREPARE: case CPU_DOWN_PREPARE_FROZEN: -- cgit v1.2.3 From 43cf38eb5cea91245502df3fcee4dbfc1c74dd1c Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Tue, 2 Feb 2010 14:38:57 +0900 Subject: percpu: add __percpu sparse annotations to core kernel subsystems Add __percpu sparse annotations to core subsystems. These annotations are to make sparse consider percpu variables to be in a different address space and warn if accessed without going through percpu accessors. This patch doesn't affect normal builds. Signed-off-by: Tejun Heo Reviewed-by: Christoph Lameter Acked-by: Paul E. McKenney Cc: Jens Axboe Cc: linux-mm@kvack.org Cc: Rusty Russell Cc: Dipankar Sarma Cc: Peter Zijlstra Cc: Andrew Morton Cc: Eric Biederman --- mm/percpu.c | 18 ++++++++++-------- 1 file changed, 10 insertions(+), 8 deletions(-) (limited to 'mm') diff --git a/mm/percpu.c b/mm/percpu.c index b336638d20e..768419d44ad 100644 --- a/mm/percpu.c +++ b/mm/percpu.c @@ -80,13 +80,15 @@ /* default addr <-> pcpu_ptr mapping, override in asm/percpu.h if necessary */ #ifndef __addr_to_pcpu_ptr #define __addr_to_pcpu_ptr(addr) \ - (void *)((unsigned long)(addr) - (unsigned long)pcpu_base_addr \ - + (unsigned long)__per_cpu_start) + (void __percpu *)((unsigned long)(addr) - \ + (unsigned long)pcpu_base_addr + \ + (unsigned long)__per_cpu_start) #endif #ifndef __pcpu_ptr_to_addr #define __pcpu_ptr_to_addr(ptr) \ - (void *)((unsigned long)(ptr) + (unsigned long)pcpu_base_addr \ - - (unsigned long)__per_cpu_start) + (void __force *)((unsigned long)(ptr) + \ + (unsigned long)pcpu_base_addr - \ + (unsigned long)__per_cpu_start) #endif struct pcpu_chunk { @@ -1065,7 +1067,7 @@ static struct pcpu_chunk *alloc_pcpu_chunk(void) * RETURNS: * Percpu pointer to the allocated area on success, NULL on failure. */ -static void *pcpu_alloc(size_t size, size_t align, bool reserved) +static void __percpu *pcpu_alloc(size_t size, size_t align, bool reserved) { static int warn_limit = 10; struct pcpu_chunk *chunk; @@ -1194,7 +1196,7 @@ fail_unlock_mutex: * RETURNS: * Percpu pointer to the allocated area on success, NULL on failure. */ -void *__alloc_percpu(size_t size, size_t align) +void __percpu *__alloc_percpu(size_t size, size_t align) { return pcpu_alloc(size, align, false); } @@ -1215,7 +1217,7 @@ EXPORT_SYMBOL_GPL(__alloc_percpu); * RETURNS: * Percpu pointer to the allocated area on success, NULL on failure. */ -void *__alloc_reserved_percpu(size_t size, size_t align) +void __percpu *__alloc_reserved_percpu(size_t size, size_t align) { return pcpu_alloc(size, align, true); } @@ -1267,7 +1269,7 @@ static void pcpu_reclaim(struct work_struct *work) * CONTEXT: * Can be called from atomic context. */ -void free_percpu(void *ptr) +void free_percpu(void __percpu *ptr) { void *addr; struct pcpu_chunk *chunk; -- cgit v1.2.3