path: root/arch/x86/kernel/setup_percpu.c
diff options
authorTejun Heo <>2009-08-14 15:00:51 +0900
committerTejun Heo <>2009-08-14 15:00:51 +0900
commitfd1e8a1fe2b54df6c185b4fa65f181f50b9c4d4e (patch)
treed4411507baacaa33c68be7813ad6f9e0d93a74e2 /arch/x86/kernel/setup_percpu.c
parent033e48fb82958053113178264ddb9d5038d5e38b (diff)
percpu: introduce pcpu_alloc_info and pcpu_group_info
Till now, non-linear cpu->unit map was expressed using an integer array which maps each cpu to a unit and used only by lpage allocator. Although how many units have been placed in a single contiguos area (group) is known while building unit_map, the information is lost when the result is recorded into the unit_map array. For lpage allocator, as all allocations are done by lpages and whether two adjacent lpages are in the same group or not is irrelevant, this didn't cause any problem. Non-linear cpu->unit mapping will be used for sparse embedding and this grouping information is necessary for that. This patch introduces pcpu_alloc_info which contains all the information necessary for initializing percpu allocator. pcpu_alloc_info contains array of pcpu_group_info which describes how units are grouped and mapped to cpus. pcpu_group_info also has base_offset field to specify its offset from the chunk's base address. pcpu_build_alloc_info() initializes this field as if all groups are allocated back-to-back as is currently done but this will be used to sparsely place groups. pcpu_alloc_info is a rather complex data structure which contains a flexible array which in turn points to nested cpu_map arrays. * pcpu_alloc_alloc_info() and pcpu_free_alloc_info() are provided to help dealing with pcpu_alloc_info. * pcpu_lpage_build_unit_map() is updated to build pcpu_alloc_info, generalized and renamed to pcpu_build_alloc_info(). @cpu_distance_fn may be NULL indicating that all cpus are of LOCAL_DISTANCE. * pcpul_lpage_dump_cfg() is updated to process pcpu_alloc_info, generalized and renamed to pcpu_dump_alloc_info(). It now also prints which group each alloc unit belongs to. * pcpu_setup_first_chunk() now takes pcpu_alloc_info instead of the separate parameters. All first chunk allocators are updated to use pcpu_build_alloc_info() to build alloc_info and call pcpu_setup_first_chunk() with it. This has the side effect of packing units for sparse possible cpus. ie. if cpus 0, 2 and 4 are possible, they'll be assigned unit 0, 1 and 2 instead of 0, 2 and 4. * x86 setup_pcpu_lpage() is updated to deal with alloc_info. * sparc64 setup_per_cpu_areas() is updated to build alloc_info. Although the changes made by this patch are pretty pervasive, it doesn't cause any behavior difference other than packing of sparse cpus. It mostly changes how information is passed among initialization functions and makes room for more flexibility. Signed-off-by: Tejun Heo <> Cc: Ingo Molnar <> Cc: David Miller <>
Diffstat (limited to 'arch/x86/kernel/setup_percpu.c')
1 files changed, 15 insertions, 23 deletions
diff --git a/arch/x86/kernel/setup_percpu.c b/arch/x86/kernel/setup_percpu.c
index 660cde133141..db5f9c49fec5 100644
--- a/arch/x86/kernel/setup_percpu.c
+++ b/arch/x86/kernel/setup_percpu.c
@@ -161,9 +161,7 @@ static ssize_t __init setup_pcpu_lpage(bool chosen)
size_t dyn_size = reserve - PERCPU_FIRST_CHUNK_RESERVE;
- size_t unit_map_size, unit_size;
- int *unit_map;
- int nr_units;
+ struct pcpu_alloc_info *ai;
ssize_t ret;
/* on non-NUMA, embedding is better */
@@ -177,26 +175,22 @@ static ssize_t __init setup_pcpu_lpage(bool chosen)
/* allocate and build unit_map */
- unit_map_size = nr_cpu_ids * sizeof(int);
- unit_map = alloc_bootmem_nopanic(unit_map_size);
- if (!unit_map) {
- pr_warning("PERCPU: failed to allocate unit_map\n");
- return -ENOMEM;
+ ai = pcpu_build_alloc_info(PERCPU_FIRST_CHUNK_RESERVE, dyn_size,
+ PMD_SIZE, pcpu_lpage_cpu_distance);
+ if (IS_ERR(ai)) {
+ pr_warning("PERCPU: failed to build unit_map (%ld)\n",
+ PTR_ERR(ai));
+ return PTR_ERR(ai);
- ret = pcpu_lpage_build_unit_map(PERCPU_FIRST_CHUNK_RESERVE,
- &dyn_size, &unit_size, PMD_SIZE,
- unit_map, pcpu_lpage_cpu_distance);
- if (ret < 0) {
- pr_warning("PERCPU: failed to build unit_map\n");
- goto out_free;
- }
- nr_units = ret;
/* do the parameters look okay? */
if (!chosen) {
size_t vm_size = VMALLOC_END - VMALLOC_START;
- size_t tot_size = nr_units * unit_size;
+ size_t tot_size = 0;
+ int group;
+ for (group = 0; group < ai->nr_groups; group++)
+ tot_size += ai->unit_size * ai->groups[group].nr_units;
/* don't consume more than 20% of vmalloc area */
if (tot_size > vm_size / 5) {
@@ -207,12 +201,10 @@ static ssize_t __init setup_pcpu_lpage(bool chosen)
- ret = pcpu_lpage_first_chunk(PERCPU_FIRST_CHUNK_RESERVE, dyn_size,
- unit_size, PMD_SIZE, unit_map, nr_units,
- pcpu_fc_alloc, pcpu_fc_free, pcpul_map);
+ ret = pcpu_lpage_first_chunk(ai, pcpu_fc_alloc, pcpu_fc_free,
+ pcpul_map);
- if (ret < 0)
- free_bootmem(__pa(unit_map), unit_map_size);
+ pcpu_free_alloc_info(ai);
return ret;