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authorLinus Torvalds <torvalds@linux-foundation.org>2010-10-22 17:31:36 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2010-10-22 17:31:36 -0700
commit0fc0531e0a2174377a86fd6953ecaa00287d8f70 (patch)
treeafe56978729300df96b002a064c9de927fadcfab /mm/percpu.c
parent91b745016c12d440386c40fb76ab69c8e08cbc06 (diff)
parent9329ba9704f6bd51a735982e0d4a3eed72c3294f (diff)
downloadvexpress-lsk-0fc0531e0a2174377a86fd6953ecaa00287d8f70.tar.gz
Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/percpu
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/percpu: percpu: update comments to reflect that percpu allocations are always zero-filled percpu: Optimize __get_cpu_var() x86, percpu: Optimize this_cpu_ptr percpu: clear memory allocated with the km allocator percpu: fix build breakage on s390 and cleanup build configuration tests percpu: use percpu allocator on UP too percpu: reduce PCPU_MIN_UNIT_SIZE to 32k vmalloc: pcpu_get/free_vm_areas() aren't needed on UP Fixed up trivial conflicts in include/linux/percpu.h
Diffstat (limited to 'mm/percpu.c')
-rw-r--r--mm/percpu.c401
1 files changed, 233 insertions, 168 deletions
diff --git a/mm/percpu.c b/mm/percpu.c
index c76ef3891e0..6fc9015534f 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 */
@@ -820,8 +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.
@@ -840,9 +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.
@@ -949,6 +956,7 @@ 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 +967,8 @@ 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;
}
@@ -1067,161 +1077,6 @@ void __init pcpu_free_alloc_info(struct pcpu_alloc_info *ai)
}
/**
- * 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;
-}
-
-/**
* pcpu_dump_alloc_info - print out information about pcpu_alloc_info
* @lvl: loglevel
* @ai: allocation info to dump
@@ -1363,7 +1218,9 @@ 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 +1345,8 @@ 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",
@@ -1515,8 +1374,180 @@ 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
@@ -1645,10 +1676,9 @@ 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
@@ -1756,10 +1786,11 @@ 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
/*
- * 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 +1801,6 @@ 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 +1829,48 @@ 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