From 4f8b02b4e5c6896e073bed736136d420bd44b627 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Fri, 3 Sep 2010 18:22:47 +0200 Subject: vmalloc: pcpu_get/free_vm_areas() aren't needed on UP These functions are used only by percpu memory allocator on SMP. Don't build them on UP. Signed-off-by: Tejun Heo Cc: Nick Piggin Reviewed-by: Chrsitoph Lameter diff --git a/include/linux/vmalloc.h b/include/linux/vmalloc.h index 01c2145..63a4fe6 100644 --- a/include/linux/vmalloc.h +++ b/include/linux/vmalloc.h @@ -117,10 +117,12 @@ extern rwlock_t vmlist_lock; extern struct vm_struct *vmlist; extern __init void vm_area_register_early(struct vm_struct *vm, size_t align); +#ifdef CONFIG_SMP struct vm_struct **pcpu_get_vm_areas(const unsigned long *offsets, const size_t *sizes, int nr_vms, size_t align, gfp_t gfp_mask); void pcpu_free_vm_areas(struct vm_struct **vms, int nr_vms); +#endif #endif /* _LINUX_VMALLOC_H */ diff --git a/mm/vmalloc.c b/mm/vmalloc.c index 6b8889d..c623e0c 100644 --- a/mm/vmalloc.c +++ b/mm/vmalloc.c @@ -2056,6 +2056,7 @@ void free_vm_area(struct vm_struct *area) } EXPORT_SYMBOL_GPL(free_vm_area); +#ifdef CONFIG_SMP static struct vmap_area *node_to_va(struct rb_node *n) { return n ? rb_entry(n, struct vmap_area, rb_node) : NULL; @@ -2336,6 +2337,7 @@ void pcpu_free_vm_areas(struct vm_struct **vms, int nr_vms) free_vm_area(vms[i]); kfree(vms); } +#endif /* CONFIG_SMP */ #ifdef CONFIG_PROC_FS static void *s_start(struct seq_file *m, loff_t *pos) -- cgit v0.10.2 From 6abad5acac09921f4944af77d3860f82d49f528d Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Fri, 3 Sep 2010 18:22:47 +0200 Subject: percpu: reduce PCPU_MIN_UNIT_SIZE to 32k In preparation of enabling percpu allocator for UP, reduce PCPU_MIN_UNIT_SIZE to 32k. On UP, the first chunk doesn't have to include static percpu variables and chunk size can be smaller which is important as UP percpu allocator will use contiguous kernel memory to populate chunks. PCPU_MIN_UNIT_SIZE also determines the maximum supported allocation size but 32k should still be enough. Signed-off-by: Tejun Heo Reviewed-by: Christoph Lameter diff --git a/include/linux/percpu.h b/include/linux/percpu.h index 49466b1..fc8130a 100644 --- a/include/linux/percpu.h +++ b/include/linux/percpu.h @@ -42,7 +42,7 @@ #ifdef CONFIG_SMP /* minimum unit size, also is the maximum supported allocation size */ -#define PCPU_MIN_UNIT_SIZE PFN_ALIGN(64 << 10) +#define PCPU_MIN_UNIT_SIZE PFN_ALIGN(32 << 10) /* * Percpu allocator can serve percpu allocations before slab is -- cgit v0.10.2 From bbddff0545878a8649c091a9dd7c43ce91516734 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Fri, 3 Sep 2010 18:22:48 +0200 Subject: percpu: use percpu allocator on UP too On UP, percpu allocations were redirected to kmalloc. This has the following problems. * For certain amount of allocations (determined by PERCPU_DYNAMIC_EARLY_SLOTS and PERCPU_DYNAMIC_EARLY_SIZE), percpu allocator can be used before the usual kernel memory allocator is brought online. On SMP, this is used to initialize the kernel memory allocator. * percpu allocator honors alignment upto PAGE_SIZE but kmalloc() doesn't. For example, workqueue makes use of larger alignments for cpu_workqueues. Currently, users of percpu allocators need to handle UP differently, which is somewhat fragile and ugly. Other than small amount of memory, there isn't much to lose by enabling percpu allocator on UP. It can simply use kernel memory based chunk allocation which was added for SMP archs w/o MMUs. This patch removes mm/percpu_up.c, builds mm/percpu.c on UP too and makes UP build use percpu-km. As percpu addresses and kernel addresses are always identity mapped and static percpu variables don't need any special treatment, nothing is arch dependent and mm/percpu.c implements generic setup_per_cpu_areas() for UP. Signed-off-by: Tejun Heo Reviewed-by: Christoph Lameter Acked-by: Pekka Enberg diff --git a/include/linux/percpu.h b/include/linux/percpu.h index fc8130a..aeeeef1 100644 --- a/include/linux/percpu.h +++ b/include/linux/percpu.h @@ -39,8 +39,6 @@ preempt_enable(); \ } while (0) -#ifdef CONFIG_SMP - /* minimum unit size, also is the maximum supported allocation size */ #define PCPU_MIN_UNIT_SIZE PFN_ALIGN(32 << 10) @@ -137,37 +135,20 @@ extern int __init pcpu_page_first_chunk(size_t reserved_size, * dynamically allocated. Non-atomic access to the current CPU's * version should probably be combined with get_cpu()/put_cpu(). */ +#ifdef CONFIG_SMP #define per_cpu_ptr(ptr, cpu) SHIFT_PERCPU_PTR((ptr), per_cpu_offset((cpu))) +#else +#define per_cpu_ptr(ptr, cpu) ({ (void)(cpu); VERIFY_PERCPU_PTR((ptr)); }) +#endif extern void __percpu *__alloc_reserved_percpu(size_t size, size_t align); extern bool is_kernel_percpu_address(unsigned long addr); -#ifndef CONFIG_HAVE_SETUP_PER_CPU_AREA +#if !defined(CONFIG_SMP) || !defined(CONFIG_HAVE_SETUP_PER_CPU_AREA) extern void __init setup_per_cpu_areas(void); #endif extern void __init percpu_init_late(void); -#else /* CONFIG_SMP */ - -#define per_cpu_ptr(ptr, cpu) ({ (void)(cpu); VERIFY_PERCPU_PTR((ptr)); }) - -/* can't distinguish from other static vars, always false */ -static inline bool is_kernel_percpu_address(unsigned long addr) -{ - return false; -} - -static inline void __init setup_per_cpu_areas(void) { } - -static inline void __init percpu_init_late(void) { } - -static inline void *pcpu_lpage_remapped(void *kaddr) -{ - return NULL; -} - -#endif /* CONFIG_SMP */ - extern void __percpu *__alloc_percpu(size_t size, size_t align); extern void free_percpu(void __percpu *__pdata); extern phys_addr_t per_cpu_ptr_to_phys(void *addr); diff --git a/mm/Kconfig b/mm/Kconfig index f4e516e..01a5744 100644 --- a/mm/Kconfig +++ b/mm/Kconfig @@ -301,3 +301,11 @@ config NOMMU_INITIAL_TRIM_EXCESS of 1 says that all excess pages should be trimmed. See Documentation/nommu-mmap.txt for more information. + +# +# UP and nommu archs use km based percpu allocator +# +config NEED_PER_CPU_KM + depends on !SMP + bool + default y diff --git a/mm/Makefile b/mm/Makefile index 34b2546..f73f75a 100644 --- a/mm/Makefile +++ b/mm/Makefile @@ -11,7 +11,7 @@ obj-y := bootmem.o filemap.o mempool.o oom_kill.o fadvise.o \ maccess.o page_alloc.o page-writeback.o \ readahead.o swap.o truncate.o vmscan.o shmem.o \ prio_tree.o util.o mmzone.o vmstat.o backing-dev.o \ - page_isolation.o mm_init.o mmu_context.o \ + page_isolation.o mm_init.o mmu_context.o percpu.o \ $(mmu-y) obj-y += init-mm.o @@ -36,11 +36,6 @@ obj-$(CONFIG_FAILSLAB) += failslab.o obj-$(CONFIG_MEMORY_HOTPLUG) += memory_hotplug.o obj-$(CONFIG_FS_XIP) += filemap_xip.o obj-$(CONFIG_MIGRATION) += migrate.o -ifdef CONFIG_SMP -obj-y += percpu.o -else -obj-y += percpu_up.o -endif obj-$(CONFIG_QUICKLIST) += quicklist.o obj-$(CONFIG_CGROUP_MEM_RES_CTLR) += memcontrol.o page_cgroup.o obj-$(CONFIG_MEMORY_FAILURE) += memory-failure.o diff --git a/mm/percpu-km.c b/mm/percpu-km.c index df68085..7037bc7 100644 --- a/mm/percpu-km.c +++ b/mm/percpu-km.c @@ -27,7 +27,7 @@ * chunk size is not aligned. percpu-km code will whine about it. */ -#ifdef CONFIG_NEED_PER_CPU_PAGE_FIRST_CHUNK +#if defined(CONFIG_SMP) && defined(CONFIG_NEED_PER_CPU_PAGE_FIRST_CHUNK) #error "contiguous percpu allocation is incompatible with paged first chunk" #endif diff --git a/mm/percpu.c b/mm/percpu.c index 58c572b..fa70122 100644 --- a/mm/percpu.c +++ b/mm/percpu.c @@ -76,6 +76,7 @@ #define PCPU_SLOT_BASE_SHIFT 5 /* 1-31 shares the same slot */ #define PCPU_DFL_MAP_ALLOC 16 /* start a map with 16 ents */ +#ifdef CONFIG_SMP /* default addr <-> pcpu_ptr mapping, override in asm/percpu.h if necessary */ #ifndef __addr_to_pcpu_ptr #define __addr_to_pcpu_ptr(addr) \ @@ -89,6 +90,11 @@ (unsigned long)pcpu_base_addr - \ (unsigned long)__per_cpu_start) #endif +#else /* CONFIG_SMP */ +/* on UP, it's always identity mapped */ +#define __addr_to_pcpu_ptr(addr) (void __percpu *)(addr) +#define __pcpu_ptr_to_addr(ptr) (void __force *)(ptr) +#endif /* CONFIG_SMP */ struct pcpu_chunk { struct list_head list; /* linked to pcpu_slot lists */ @@ -949,6 +955,7 @@ EXPORT_SYMBOL_GPL(free_percpu); */ bool is_kernel_percpu_address(unsigned long addr) { +#ifdef CONFIG_SMP const size_t static_size = __per_cpu_end - __per_cpu_start; void __percpu *base = __addr_to_pcpu_ptr(pcpu_base_addr); unsigned int cpu; @@ -959,6 +966,8 @@ bool is_kernel_percpu_address(unsigned long addr) if ((void *)addr >= start && (void *)addr < start + static_size) return true; } +#endif + /* on UP, can't distinguish from other static vars, always false */ return false; } @@ -1066,6 +1075,8 @@ void __init pcpu_free_alloc_info(struct pcpu_alloc_info *ai) free_bootmem(__pa(ai), ai->__ai_size); } +#if defined(CONFIG_SMP) && (defined(CONFIG_NEED_PER_CPU_EMBED_FIRST_CHUNK) || \ + defined(CONFIG_NEED_PER_CPU_PAGE_FIRST_CHUNK)) /** * pcpu_build_alloc_info - build alloc_info considering distances between CPUs * @reserved_size: the size of reserved percpu area in bytes @@ -1220,6 +1231,8 @@ static struct pcpu_alloc_info * __init pcpu_build_alloc_info( return ai; } +#endif /* CONFIG_SMP && (CONFIG_NEED_PER_CPU_EMBED_FIRST_CHUNK || + CONFIG_NEED_PER_CPU_PAGE_FIRST_CHUNK) */ /** * pcpu_dump_alloc_info - print out information about pcpu_alloc_info @@ -1363,7 +1376,9 @@ int __init pcpu_setup_first_chunk(const struct pcpu_alloc_info *ai, /* sanity checks */ PCPU_SETUP_BUG_ON(ai->nr_groups <= 0); +#ifdef CONFIG_SMP PCPU_SETUP_BUG_ON(!ai->static_size); +#endif PCPU_SETUP_BUG_ON(!base_addr); PCPU_SETUP_BUG_ON(ai->unit_size < size_sum); PCPU_SETUP_BUG_ON(ai->unit_size & ~PAGE_MASK); @@ -1488,6 +1503,8 @@ int __init pcpu_setup_first_chunk(const struct pcpu_alloc_info *ai, return 0; } +#ifdef CONFIG_SMP + const char *pcpu_fc_names[PCPU_FC_NR] __initdata = { [PCPU_FC_AUTO] = "auto", [PCPU_FC_EMBED] = "embed", @@ -1758,8 +1775,9 @@ out_free_ar: } #endif /* CONFIG_NEED_PER_CPU_PAGE_FIRST_CHUNK */ +#ifndef CONFIG_HAVE_SETUP_PER_CPU_AREA /* - * Generic percpu area setup. + * Generic SMP percpu area setup. * * The embedding helper is used because its behavior closely resembles * the original non-dynamic generic percpu area setup. This is @@ -1770,7 +1788,6 @@ out_free_ar: * on the physical linear memory mapping which uses large page * mappings on applicable archs. */ -#ifndef CONFIG_HAVE_SETUP_PER_CPU_AREA unsigned long __per_cpu_offset[NR_CPUS] __read_mostly; EXPORT_SYMBOL(__per_cpu_offset); @@ -1799,13 +1816,48 @@ void __init setup_per_cpu_areas(void) PERCPU_DYNAMIC_RESERVE, PAGE_SIZE, NULL, pcpu_dfl_fc_alloc, pcpu_dfl_fc_free); if (rc < 0) - panic("Failed to initialized percpu areas."); + panic("Failed to initialize percpu areas."); delta = (unsigned long)pcpu_base_addr - (unsigned long)__per_cpu_start; for_each_possible_cpu(cpu) __per_cpu_offset[cpu] = delta + pcpu_unit_offsets[cpu]; } -#endif /* CONFIG_HAVE_SETUP_PER_CPU_AREA */ +#endif /* CONFIG_HAVE_SETUP_PER_CPU_AREA */ + +#else /* CONFIG_SMP */ + +/* + * UP percpu area setup. + * + * UP always uses km-based percpu allocator with identity mapping. + * Static percpu variables are indistinguishable from the usual static + * variables and don't require any special preparation. + */ +void __init setup_per_cpu_areas(void) +{ + const size_t unit_size = + roundup_pow_of_two(max_t(size_t, PCPU_MIN_UNIT_SIZE, + PERCPU_DYNAMIC_RESERVE)); + struct pcpu_alloc_info *ai; + void *fc; + + ai = pcpu_alloc_alloc_info(1, 1); + fc = __alloc_bootmem(unit_size, PAGE_SIZE, __pa(MAX_DMA_ADDRESS)); + if (!ai || !fc) + panic("Failed to allocate memory for percpu areas."); + + ai->dyn_size = unit_size; + ai->unit_size = unit_size; + ai->atom_size = unit_size; + ai->alloc_size = unit_size; + ai->groups[0].nr_units = 1; + ai->groups[0].cpu_map[0] = 0; + + if (pcpu_setup_first_chunk(ai, fc) < 0) + panic("Failed to initialize percpu areas."); +} + +#endif /* CONFIG_SMP */ /* * First and reserved chunks are initialized with temporary allocation diff --git a/mm/percpu_up.c b/mm/percpu_up.c deleted file mode 100644 index db884fa..0000000 --- a/mm/percpu_up.c +++ /dev/null @@ -1,30 +0,0 @@ -/* - * mm/percpu_up.c - dummy percpu memory allocator implementation for UP - */ - -#include -#include -#include - -void __percpu *__alloc_percpu(size_t size, size_t align) -{ - /* - * Can't easily make larger alignment work with kmalloc. WARN - * on it. Larger alignment should only be used for module - * percpu sections on SMP for which this path isn't used. - */ - WARN_ON_ONCE(align > SMP_CACHE_BYTES); - return (void __percpu __force *)kzalloc(size, GFP_KERNEL); -} -EXPORT_SYMBOL_GPL(__alloc_percpu); - -void free_percpu(void __percpu *p) -{ - kfree(this_cpu_ptr(p)); -} -EXPORT_SYMBOL_GPL(free_percpu); - -phys_addr_t per_cpu_ptr_to_phys(void *addr) -{ - return __pa(addr); -} -- cgit v0.10.2 From 3c9a024fde58b08745680863859d1483def64f74 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Thu, 9 Sep 2010 18:00:15 +0200 Subject: percpu: fix build breakage on s390 and cleanup build configuration tests Commit bbddff05 (percpu: use percpu allocator on UP too) incorrectly excluded pcpu_build_alloc_info() on SMP configurations which use generic setup_per_cpu_area() like s390. The config ifdefs are becoming confusing. Fix and clean it up by, * Move pcpu_build_alloc_info() right on top of its two users - pcpu_{embed|page}_first_chunk() which are already in CONFIG_SMP block. * Define BUILD_{EMBED|PAGE}_FIRST_CHUNK which indicate whether each first chunk function needs to be included and use them to control inclusion of the three functions to reduce confusion. Signed-off-by: Tejun Heo Reported-by: Sachin Sant diff --git a/mm/percpu.c b/mm/percpu.c index fa70122..0cd4bf6 100644 --- a/mm/percpu.c +++ b/mm/percpu.c @@ -1075,165 +1075,6 @@ void __init pcpu_free_alloc_info(struct pcpu_alloc_info *ai) free_bootmem(__pa(ai), ai->__ai_size); } -#if defined(CONFIG_SMP) && (defined(CONFIG_NEED_PER_CPU_EMBED_FIRST_CHUNK) || \ - defined(CONFIG_NEED_PER_CPU_PAGE_FIRST_CHUNK)) -/** - * pcpu_build_alloc_info - build alloc_info considering distances between CPUs - * @reserved_size: the size of reserved percpu area in bytes - * @dyn_size: minimum free size for dynamic allocation in bytes - * @atom_size: allocation atom size - * @cpu_distance_fn: callback to determine distance between cpus, optional - * - * This function determines grouping of units, their mappings to cpus - * and other parameters considering needed percpu size, allocation - * atom size and distances between CPUs. - * - * Groups are always mutliples of atom size and CPUs which are of - * LOCAL_DISTANCE both ways are grouped together and share space for - * units in the same group. The returned configuration is guaranteed - * to have CPUs on different nodes on different groups and >=75% usage - * of allocated virtual address space. - * - * RETURNS: - * On success, pointer to the new allocation_info is returned. On - * failure, ERR_PTR value is returned. - */ -static struct pcpu_alloc_info * __init pcpu_build_alloc_info( - size_t reserved_size, size_t dyn_size, - size_t atom_size, - pcpu_fc_cpu_distance_fn_t cpu_distance_fn) -{ - static int group_map[NR_CPUS] __initdata; - static int group_cnt[NR_CPUS] __initdata; - const size_t static_size = __per_cpu_end - __per_cpu_start; - int nr_groups = 1, nr_units = 0; - size_t size_sum, min_unit_size, alloc_size; - int upa, max_upa, uninitialized_var(best_upa); /* units_per_alloc */ - int last_allocs, group, unit; - unsigned int cpu, tcpu; - struct pcpu_alloc_info *ai; - unsigned int *cpu_map; - - /* this function may be called multiple times */ - memset(group_map, 0, sizeof(group_map)); - memset(group_cnt, 0, sizeof(group_cnt)); - - /* calculate size_sum and ensure dyn_size is enough for early alloc */ - size_sum = PFN_ALIGN(static_size + reserved_size + - max_t(size_t, dyn_size, PERCPU_DYNAMIC_EARLY_SIZE)); - dyn_size = size_sum - static_size - reserved_size; - - /* - * Determine min_unit_size, alloc_size and max_upa such that - * alloc_size is multiple of atom_size and is the smallest - * which can accomodate 4k aligned segments which are equal to - * or larger than min_unit_size. - */ - min_unit_size = max_t(size_t, size_sum, PCPU_MIN_UNIT_SIZE); - - alloc_size = roundup(min_unit_size, atom_size); - upa = alloc_size / min_unit_size; - while (alloc_size % upa || ((alloc_size / upa) & ~PAGE_MASK)) - upa--; - max_upa = upa; - - /* group cpus according to their proximity */ - for_each_possible_cpu(cpu) { - group = 0; - next_group: - for_each_possible_cpu(tcpu) { - if (cpu == tcpu) - break; - if (group_map[tcpu] == group && cpu_distance_fn && - (cpu_distance_fn(cpu, tcpu) > LOCAL_DISTANCE || - cpu_distance_fn(tcpu, cpu) > LOCAL_DISTANCE)) { - group++; - nr_groups = max(nr_groups, group + 1); - goto next_group; - } - } - group_map[cpu] = group; - group_cnt[group]++; - } - - /* - * Expand unit size until address space usage goes over 75% - * and then as much as possible without using more address - * space. - */ - last_allocs = INT_MAX; - for (upa = max_upa; upa; upa--) { - int allocs = 0, wasted = 0; - - if (alloc_size % upa || ((alloc_size / upa) & ~PAGE_MASK)) - continue; - - for (group = 0; group < nr_groups; group++) { - int this_allocs = DIV_ROUND_UP(group_cnt[group], upa); - allocs += this_allocs; - wasted += this_allocs * upa - group_cnt[group]; - } - - /* - * Don't accept if wastage is over 1/3. The - * greater-than comparison ensures upa==1 always - * passes the following check. - */ - if (wasted > num_possible_cpus() / 3) - continue; - - /* and then don't consume more memory */ - if (allocs > last_allocs) - break; - last_allocs = allocs; - best_upa = upa; - } - upa = best_upa; - - /* allocate and fill alloc_info */ - for (group = 0; group < nr_groups; group++) - nr_units += roundup(group_cnt[group], upa); - - ai = pcpu_alloc_alloc_info(nr_groups, nr_units); - if (!ai) - return ERR_PTR(-ENOMEM); - cpu_map = ai->groups[0].cpu_map; - - for (group = 0; group < nr_groups; group++) { - ai->groups[group].cpu_map = cpu_map; - cpu_map += roundup(group_cnt[group], upa); - } - - ai->static_size = static_size; - ai->reserved_size = reserved_size; - ai->dyn_size = dyn_size; - ai->unit_size = alloc_size / upa; - ai->atom_size = atom_size; - ai->alloc_size = alloc_size; - - for (group = 0, unit = 0; group_cnt[group]; group++) { - struct pcpu_group_info *gi = &ai->groups[group]; - - /* - * Initialize base_offset as if all groups are located - * back-to-back. The caller should update this to - * reflect actual allocation. - */ - gi->base_offset = unit * ai->unit_size; - - for_each_possible_cpu(cpu) - if (group_map[cpu] == group) - gi->cpu_map[gi->nr_units++] = cpu; - gi->nr_units = roundup(gi->nr_units, upa); - unit += gi->nr_units; - } - BUG_ON(unit != nr_units); - - return ai; -} -#endif /* CONFIG_SMP && (CONFIG_NEED_PER_CPU_EMBED_FIRST_CHUNK || - CONFIG_NEED_PER_CPU_PAGE_FIRST_CHUNK) */ - /** * pcpu_dump_alloc_info - print out information about pcpu_alloc_info * @lvl: loglevel @@ -1532,8 +1373,180 @@ static int __init percpu_alloc_setup(char *str) } early_param("percpu_alloc", percpu_alloc_setup); +/* + * pcpu_embed_first_chunk() is used by the generic percpu setup. + * Build it if needed by the arch config or the generic setup is going + * to be used. + */ #if defined(CONFIG_NEED_PER_CPU_EMBED_FIRST_CHUNK) || \ !defined(CONFIG_HAVE_SETUP_PER_CPU_AREA) +#define BUILD_EMBED_FIRST_CHUNK +#endif + +/* build pcpu_page_first_chunk() iff needed by the arch config */ +#if defined(CONFIG_NEED_PER_CPU_PAGE_FIRST_CHUNK) +#define BUILD_PAGE_FIRST_CHUNK +#endif + +/* pcpu_build_alloc_info() is used by both embed and page first chunk */ +#if defined(BUILD_EMBED_FIRST_CHUNK) || defined(BUILD_PAGE_FIRST_CHUNK) +/** + * pcpu_build_alloc_info - build alloc_info considering distances between CPUs + * @reserved_size: the size of reserved percpu area in bytes + * @dyn_size: minimum free size for dynamic allocation in bytes + * @atom_size: allocation atom size + * @cpu_distance_fn: callback to determine distance between cpus, optional + * + * This function determines grouping of units, their mappings to cpus + * and other parameters considering needed percpu size, allocation + * atom size and distances between CPUs. + * + * Groups are always mutliples of atom size and CPUs which are of + * LOCAL_DISTANCE both ways are grouped together and share space for + * units in the same group. The returned configuration is guaranteed + * to have CPUs on different nodes on different groups and >=75% usage + * of allocated virtual address space. + * + * RETURNS: + * On success, pointer to the new allocation_info is returned. On + * failure, ERR_PTR value is returned. + */ +static struct pcpu_alloc_info * __init pcpu_build_alloc_info( + size_t reserved_size, size_t dyn_size, + size_t atom_size, + pcpu_fc_cpu_distance_fn_t cpu_distance_fn) +{ + static int group_map[NR_CPUS] __initdata; + static int group_cnt[NR_CPUS] __initdata; + const size_t static_size = __per_cpu_end - __per_cpu_start; + int nr_groups = 1, nr_units = 0; + size_t size_sum, min_unit_size, alloc_size; + int upa, max_upa, uninitialized_var(best_upa); /* units_per_alloc */ + int last_allocs, group, unit; + unsigned int cpu, tcpu; + struct pcpu_alloc_info *ai; + unsigned int *cpu_map; + + /* this function may be called multiple times */ + memset(group_map, 0, sizeof(group_map)); + memset(group_cnt, 0, sizeof(group_cnt)); + + /* calculate size_sum and ensure dyn_size is enough for early alloc */ + size_sum = PFN_ALIGN(static_size + reserved_size + + max_t(size_t, dyn_size, PERCPU_DYNAMIC_EARLY_SIZE)); + dyn_size = size_sum - static_size - reserved_size; + + /* + * Determine min_unit_size, alloc_size and max_upa such that + * alloc_size is multiple of atom_size and is the smallest + * which can accomodate 4k aligned segments which are equal to + * or larger than min_unit_size. + */ + min_unit_size = max_t(size_t, size_sum, PCPU_MIN_UNIT_SIZE); + + alloc_size = roundup(min_unit_size, atom_size); + upa = alloc_size / min_unit_size; + while (alloc_size % upa || ((alloc_size / upa) & ~PAGE_MASK)) + upa--; + max_upa = upa; + + /* group cpus according to their proximity */ + for_each_possible_cpu(cpu) { + group = 0; + next_group: + for_each_possible_cpu(tcpu) { + if (cpu == tcpu) + break; + if (group_map[tcpu] == group && cpu_distance_fn && + (cpu_distance_fn(cpu, tcpu) > LOCAL_DISTANCE || + cpu_distance_fn(tcpu, cpu) > LOCAL_DISTANCE)) { + group++; + nr_groups = max(nr_groups, group + 1); + goto next_group; + } + } + group_map[cpu] = group; + group_cnt[group]++; + } + + /* + * Expand unit size until address space usage goes over 75% + * and then as much as possible without using more address + * space. + */ + last_allocs = INT_MAX; + for (upa = max_upa; upa; upa--) { + int allocs = 0, wasted = 0; + + if (alloc_size % upa || ((alloc_size / upa) & ~PAGE_MASK)) + continue; + + for (group = 0; group < nr_groups; group++) { + int this_allocs = DIV_ROUND_UP(group_cnt[group], upa); + allocs += this_allocs; + wasted += this_allocs * upa - group_cnt[group]; + } + + /* + * Don't accept if wastage is over 1/3. The + * greater-than comparison ensures upa==1 always + * passes the following check. + */ + if (wasted > num_possible_cpus() / 3) + continue; + + /* and then don't consume more memory */ + if (allocs > last_allocs) + break; + last_allocs = allocs; + best_upa = upa; + } + upa = best_upa; + + /* allocate and fill alloc_info */ + for (group = 0; group < nr_groups; group++) + nr_units += roundup(group_cnt[group], upa); + + ai = pcpu_alloc_alloc_info(nr_groups, nr_units); + if (!ai) + return ERR_PTR(-ENOMEM); + cpu_map = ai->groups[0].cpu_map; + + for (group = 0; group < nr_groups; group++) { + ai->groups[group].cpu_map = cpu_map; + cpu_map += roundup(group_cnt[group], upa); + } + + ai->static_size = static_size; + ai->reserved_size = reserved_size; + ai->dyn_size = dyn_size; + ai->unit_size = alloc_size / upa; + ai->atom_size = atom_size; + ai->alloc_size = alloc_size; + + for (group = 0, unit = 0; group_cnt[group]; group++) { + struct pcpu_group_info *gi = &ai->groups[group]; + + /* + * Initialize base_offset as if all groups are located + * back-to-back. The caller should update this to + * reflect actual allocation. + */ + gi->base_offset = unit * ai->unit_size; + + for_each_possible_cpu(cpu) + if (group_map[cpu] == group) + gi->cpu_map[gi->nr_units++] = cpu; + gi->nr_units = roundup(gi->nr_units, upa); + unit += gi->nr_units; + } + BUG_ON(unit != nr_units); + + return ai; +} +#endif /* BUILD_EMBED_FIRST_CHUNK || BUILD_PAGE_FIRST_CHUNK */ + +#if defined(BUILD_EMBED_FIRST_CHUNK) /** * pcpu_embed_first_chunk - embed the first percpu chunk into bootmem * @reserved_size: the size of reserved percpu area in bytes @@ -1662,10 +1675,9 @@ out_free: free_bootmem(__pa(areas), areas_size); return rc; } -#endif /* CONFIG_NEED_PER_CPU_EMBED_FIRST_CHUNK || - !CONFIG_HAVE_SETUP_PER_CPU_AREA */ +#endif /* BUILD_EMBED_FIRST_CHUNK */ -#ifdef CONFIG_NEED_PER_CPU_PAGE_FIRST_CHUNK +#ifdef BUILD_PAGE_FIRST_CHUNK /** * pcpu_page_first_chunk - map the first chunk using PAGE_SIZE pages * @reserved_size: the size of reserved percpu area in bytes @@ -1773,7 +1785,7 @@ out_free_ar: pcpu_free_alloc_info(ai); return rc; } -#endif /* CONFIG_NEED_PER_CPU_PAGE_FIRST_CHUNK */ +#endif /* BUILD_PAGE_FIRST_CHUNK */ #ifndef CONFIG_HAVE_SETUP_PER_CPU_AREA /* -- cgit v0.10.2 From fc1481a956181d0360d3eb129965302489895a1b Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Fri, 10 Sep 2010 10:49:37 +0200 Subject: percpu: clear memory allocated with the km allocator Percpu allocator should clear memory before returning it but the km allocator forgot to do it. Fix it. Signed-off-by: Tejun Heo Reported-by: Peter Zijlstra Acked-by: Peter Zijlstra diff --git a/mm/percpu-km.c b/mm/percpu-km.c index 7037bc7..89633fe 100644 --- a/mm/percpu-km.c +++ b/mm/percpu-km.c @@ -35,7 +35,11 @@ static int pcpu_populate_chunk(struct pcpu_chunk *chunk, int off, int size) { - /* noop */ + unsigned int cpu; + + for_each_possible_cpu(cpu) + memset((void *)pcpu_chunk_addr(chunk, cpu, 0) + off, 0, size); + return 0; } -- cgit v0.10.2 From db7829c6cc32f3c0c9a324118d743acb1abff081 Mon Sep 17 00:00:00 2001 From: Brian Gerst Date: Thu, 9 Sep 2010 18:17:26 +0200 Subject: x86, percpu: Optimize this_cpu_ptr Allow arches to implement __this_cpu_ptr, and provide an x86 version. Before: movq $foo, %rax movq %gs:this_cpu_off, %rdx addq %rdx, %rax After: movq $foo, %rax addq %gs:this_cpu_off, %rax The benefit is doing it in one less instruction and not clobbering a temporary register. tj: * Beefed up the comment a bit and renamed in-macro temp variable to match neighboring macros. * Folded fix for const pointer case found in linux-next. * Fixed sparse notation. Signed-off-by: Brian Gerst Signed-off-by: Tejun Heo diff --git a/arch/x86/include/asm/percpu.h b/arch/x86/include/asm/percpu.h index cd28f9a..f899e01 100644 --- a/arch/x86/include/asm/percpu.h +++ b/arch/x86/include/asm/percpu.h @@ -47,6 +47,20 @@ #ifdef CONFIG_SMP #define __percpu_arg(x) "%%"__stringify(__percpu_seg)":%P" #x #define __my_cpu_offset percpu_read(this_cpu_off) + +/* + * Compared to the generic __my_cpu_offset version, the following + * saves one instruction and avoids clobbering a temp register. + */ +#define __this_cpu_ptr(ptr) \ +({ \ + unsigned long tcp_ptr__; \ + __verify_pcpu_ptr(ptr); \ + asm volatile("add " __percpu_arg(1) ", %0" \ + : "=r" (tcp_ptr__) \ + : "m" (this_cpu_off), "0" (ptr)); \ + (typeof(*(ptr)) __kernel __force *)tcp_ptr__; \ +}) #else #define __percpu_arg(x) "%P" #x #endif diff --git a/include/asm-generic/percpu.h b/include/asm-generic/percpu.h index 08923b6..ec64311 100644 --- a/include/asm-generic/percpu.h +++ b/include/asm-generic/percpu.h @@ -60,9 +60,14 @@ extern unsigned long __per_cpu_offset[NR_CPUS]; #define __raw_get_cpu_var(var) \ (*SHIFT_PERCPU_PTR(&(var), __my_cpu_offset)) -#define this_cpu_ptr(ptr) SHIFT_PERCPU_PTR(ptr, my_cpu_offset) +#ifndef __this_cpu_ptr #define __this_cpu_ptr(ptr) SHIFT_PERCPU_PTR(ptr, __my_cpu_offset) - +#endif +#ifdef CONFIG_DEBUG_PREEMPT +#define this_cpu_ptr(ptr) SHIFT_PERCPU_PTR(ptr, my_cpu_offset) +#else +#define this_cpu_ptr(ptr) __this_cpu_ptr(ptr) +#endif #ifdef CONFIG_HAVE_SETUP_PER_CPU_AREA extern void setup_per_cpu_areas(void); -- cgit v0.10.2 From 677243d7494d09bfa782425f063a6013de53c35b Mon Sep 17 00:00:00 2001 From: Brian Gerst Date: Thu, 9 Sep 2010 18:17:26 +0200 Subject: percpu: Optimize __get_cpu_var() Redefine __get_cpu_var() using this_cpu_ptr() which can be arch-optimized. Signed-off-by: Brian Gerst Signed-off-by: Tejun Heo diff --git a/include/asm-generic/percpu.h b/include/asm-generic/percpu.h index ec64311..d17784e 100644 --- a/include/asm-generic/percpu.h +++ b/include/asm-generic/percpu.h @@ -55,10 +55,6 @@ extern unsigned long __per_cpu_offset[NR_CPUS]; */ #define per_cpu(var, cpu) \ (*SHIFT_PERCPU_PTR(&(var), per_cpu_offset(cpu))) -#define __get_cpu_var(var) \ - (*SHIFT_PERCPU_PTR(&(var), my_cpu_offset)) -#define __raw_get_cpu_var(var) \ - (*SHIFT_PERCPU_PTR(&(var), __my_cpu_offset)) #ifndef __this_cpu_ptr #define __this_cpu_ptr(ptr) SHIFT_PERCPU_PTR(ptr, __my_cpu_offset) @@ -69,6 +65,9 @@ extern unsigned long __per_cpu_offset[NR_CPUS]; #define this_cpu_ptr(ptr) __this_cpu_ptr(ptr) #endif +#define __get_cpu_var(var) (*this_cpu_ptr(&(var))) +#define __raw_get_cpu_var(var) (*__this_cpu_ptr(&(var))) + #ifdef CONFIG_HAVE_SETUP_PER_CPU_AREA extern void setup_per_cpu_areas(void); #endif -- cgit v0.10.2 From 9329ba9704f6bd51a735982e0d4a3eed72c3294f Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Fri, 10 Sep 2010 11:01:56 +0200 Subject: percpu: update comments to reflect that percpu allocations are always zero-filled Signed-off-by: Tejun Heo Reported-by: Stephane Eranian diff --git a/mm/percpu.c b/mm/percpu.c index 0cd4bf6..12dea33 100644 --- a/mm/percpu.c +++ b/mm/percpu.c @@ -826,8 +826,8 @@ fail_unlock_mutex: * @size: size of area to allocate in bytes * @align: alignment of area (max PAGE_SIZE) * - * Allocate percpu area of @size bytes aligned at @align. Might - * sleep. Might trigger writeouts. + * Allocate zero-filled percpu area of @size bytes aligned at @align. + * Might sleep. Might trigger writeouts. * * CONTEXT: * Does GFP_KERNEL allocation. @@ -846,9 +846,10 @@ EXPORT_SYMBOL_GPL(__alloc_percpu); * @size: size of area to allocate in bytes * @align: alignment of area (max PAGE_SIZE) * - * Allocate percpu area of @size bytes aligned at @align from reserved - * percpu area if arch has set it up; otherwise, allocation is served - * from the same dynamic area. Might sleep. Might trigger writeouts. + * Allocate zero-filled percpu area of @size bytes aligned at @align + * from reserved percpu area if arch has set it up; otherwise, + * allocation is served from the same dynamic area. Might sleep. + * Might trigger writeouts. * * CONTEXT: * Does GFP_KERNEL allocation. -- cgit v0.10.2