[PATCH 3/6] x86,percpu: generalize 4k first chunk allocator

Tejun Heo
2009-06-17T04:07:57Z

Generalize and move x86 setup_pcpu_4k() into pcpu_4k_first_chunk().
setup_pcpu_4k() now is a simple wrapper around the generalized
version. Other than taking size parameters and using arch supplied
callbacks to allocate/free memory, pcpu_4k_first_chunk() is identical
to the original implementation.

This simplifies arch code and will help converting more archs to
dynamic percpu allocator.

While at it, s/pcpu_populate_pte_fn_t/pcpu_fc_populate_pte_fn_t/ for
consistency.

[ Impact: code reorganization and generalization ]

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Ingo Molnar <mingo@elte.hu>
---
arch/x86/kernel/setup_percpu.c | 78 +++++++++---------------------------
include/linux/percpu.h | 12 +++++-
mm/percpu.c | 85 +++++++++++++++++++++++++++++++++++++++-
3 files changed, 113 insertions(+), 62 deletions(-)

diff --git a/arch/x86/kernel/setup_percpu.c b/arch/x86/kernel/setup_percpu.c
index 1472820..ab896b3 100644
--- a/arch/x86/kernel/setup_percpu.c
+++ b/arch/x86/kernel/setup_percpu.c
@@ -124,6 +124,19 @@ static void * __init pcpu_alloc_bootmem(unsigned int cpu, unsigned long size,
}

/*
+ * Helpers for first chunk memory allocation
+ */
+static void * __init pcpu_fc_alloc(unsigned int cpu, size_t size)
+{
+ return pcpu_alloc_bootmem(cpu, size, size);
+}
+
+static void __init pcpu_fc_free(void *ptr, size_t size)
+{
+ free_bootmem(__pa(ptr), size);
+}
+
+/*
* Large page remap allocator
*
* This allocator uses PMD page as unit. A PMD page is allocated for
@@ -346,22 +359,11 @@ static ssize_t __init setup_pcpu_embed(size_t static_size, bool chosen)
}

/*
- * 4k page allocator
+ * 4k allocator
*
- * This is the basic allocator. Static percpu area is allocated
- * page-by-page and most of initialization is done by the generic
- * setup function.
+ * Boring fallback 4k allocator. This allocator puts more pressure on
+ * PTE TLBs but other than that behaves nicely on both UMA and NUMA.
*/
-static struct page **pcpu4k_pages __initdata;
-static int pcpu4k_nr_static_pages __initdata;
-
-static struct page * __init pcpu4k_get_page(unsigned int cpu, int pageno)
-{
- if (pageno < pcpu4k_nr_static_pages)
- return pcpu4k_pages[cpu * pcpu4k_nr_static_pages + pageno];
- return NULL;
-}
-
static void __init pcpu4k_populate_pte(unsigned long addr)
{
populate_extra_pte(addr);
@@ -369,51 +371,9 @@ static void __init pcpu4k_populate_pte(unsigned long addr)

static ssize_t __init setup_pcpu_4k(size_t static_size)
{
- size_t pages_size;
- unsigned int cpu;
- int i, j;
- ssize_t ret;
-
- pcpu4k_nr_static_pages = PFN_UP(static_size);
-
- /* unaligned allocations can't be freed, round up to page size */
- pages_size = PFN_ALIGN(pcpu4k_nr_static_pages * num_possible_cpus()
- * sizeof(pcpu4k_pages[0]));
- pcpu4k_pages = alloc_bootmem(pages_size);
-
- /* allocate and copy */
- j = 0;
- for_each_possible_cpu(cpu)
- for (i = 0; i < pcpu4k_nr_static_pages; i++) {
- void *ptr;
-
- ptr = pcpu_alloc_bootmem(cpu, PAGE_SIZE, PAGE_SIZE);
- if (!ptr) {
- pr_warning("PERCPU: failed to allocate "
- "4k page for cpu%u\n", cpu);
- goto enomem;
- }
-
- memcpy(ptr, __per_cpu_load + i * PAGE_SIZE, PAGE_SIZE);
- pcpu4k_pages[j++] = virt_to_page(ptr);
- }
-
- /* we're ready, commit */
- pr_info("PERCPU: Allocated %d 4k pages, static data %zu bytes\n",
- pcpu4k_nr_static_pages, static_size);
-
- ret = pcpu_setup_first_chunk(pcpu4k_get_page, static_size,
- PERCPU_FIRST_CHUNK_RESERVE, -1,
- -1, NULL, pcpu4k_populate_pte);
- goto out_free_ar;
-
-enomem:
- while (--j >= 0)
- free_bootmem(__pa(page_address(pcpu4k_pages[j])), PAGE_SIZE);
- ret = -ENOMEM;
-out_free_ar:
- free_bootmem(__pa(pcpu4k_pages), pages_size);
- return ret;
+ return pcpu_4k_first_chunk(static_size, PERCPU_FIRST_CHUNK_RESERVE,
+ pcpu_fc_alloc, pcpu_fc_free,
+ pcpu4k_populate_pte);
}

/* for explicit first chunk allocator selection */
diff --git a/include/linux/percpu.h b/include/linux/percpu.h
index 83bff05..41b5bfa 100644
--- a/include/linux/percpu.h
+++ b/include/linux/percpu.h
@@ -59,18 +59,26 @@
extern void *pcpu_base_addr;

typedef struct page * (*pcpu_get_page_fn_t)(unsigned int cpu, int pageno);
-typedef void (*pcpu_populate_pte_fn_t)(unsigned long addr);
+typedef void * (*pcpu_fc_alloc_fn_t)(unsigned int cpu, size_t size);
+typedef void (*pcpu_fc_free_fn_t)(void *ptr, size_t size);
+typedef void (*pcpu_fc_populate_pte_fn_t)(unsigned long addr);

extern size_t __init pcpu_setup_first_chunk(pcpu_get_page_fn_t get_page_fn,
size_t static_size, size_t reserved_size,
ssize_t dyn_size, ssize_t unit_size,
void *base_addr,
- pcpu_populate_pte_fn_t populate_pte_fn);
+ pcpu_fc_populate_pte_fn_t populate_pte_fn);

extern ssize_t __init pcpu_embed_first_chunk(
size_t static_size, size_t reserved_size,
ssize_t dyn_size);

+extern ssize_t __init pcpu_4k_first_chunk(
+ size_t static_size, size_t reserved_size,
+ pcpu_fc_alloc_fn_t alloc_fn,
+ pcpu_fc_free_fn_t free_fn,
+ pcpu_fc_populate_pte_fn_t populate_pte_fn);
+
/*
* Use this to get to a cpu's version of the per-cpu object
* dynamically allocated. Non-atomic access to the current CPU's
diff --git a/mm/percpu.c b/mm/percpu.c
index fe34b6b..39f4022 100644
--- a/mm/percpu.c
+++ b/mm/percpu.c
@@ -1037,7 +1037,7 @@ size_t __init pcpu_setup_first_chunk(pcpu_get_page_fn_t get_page_fn,
size_t static_size, size_t reserved_size,
ssize_t dyn_size, ssize_t unit_size,
void *base_addr,
- pcpu_populate_pte_fn_t populate_pte_fn)
+ pcpu_fc_populate_pte_fn_t populate_pte_fn)
{
static struct vm_struct first_vm;
static int smap[2], dmap[2];
@@ -1271,6 +1271,89 @@ ssize_t __init pcpu_embed_first_chunk(size_t static_size, size_t reserved_size,
}

/*
+ * 4k page first chunk setup helper.
+ */
+static struct page **pcpu4k_pages __initdata;
+static int pcpu4k_nr_static_pages __initdata;
+
+static struct page * __init pcpu4k_get_page(unsigned int cpu, int pageno)
+{
+ if (pageno < pcpu4k_nr_static_pages)
+ return pcpu4k_pages[cpu * pcpu4k_nr_static_pages + pageno];
+ return NULL;
+}
+
+/**
+ * pcpu_4k_first_chunk - map the first chunk using PAGE_SIZE pages
+ * @static_size: the size of static percpu area in bytes
+ * @reserved_size: the size of reserved percpu area in bytes
+ * @alloc_fn: function to allocate percpu page, always called with PAGE_SIZE
+ * @free_fn: funtion to free percpu page, always called with PAGE_SIZE
+ * @populate_pte_fn: function to populate pte
+ *
+ * This is a helper to ease setting up embedded first percpu chunk and
+ * can be called where pcpu_setup_first_chunk() is expected.
+ *
+ * This is the basic allocator. Static percpu area is allocated
+ * page-by-page into vmalloc area.
+ *
+ * RETURNS:
+ * The determined pcpu_unit_size which can be used to initialize
+ * percpu access on success, -errno on failure.
+ */
+ssize_t __init pcpu_4k_first_chunk(size_t static_size, size_t reserved_size,
+ pcpu_fc_alloc_fn_t alloc_fn,
+ pcpu_fc_free_fn_t free_fn,
+ pcpu_fc_populate_pte_fn_t populate_pte_fn)
+{
+ size_t pages_size;
+ unsigned int cpu;
+ int i, j;
+ ssize_t ret;
+
+ pcpu4k_nr_static_pages = PFN_UP(static_size);
+
+ /* unaligned allocations can't be freed, round up to page size */
+ pages_size = PFN_ALIGN(pcpu4k_nr_static_pages * num_possible_cpus() *
+ sizeof(pcpu4k_pages[0]));
+ pcpu4k_pages = alloc_bootmem(pages_size);
+
+ /* allocate and copy */
+ j = 0;
+ for_each_possible_cpu(cpu)
+ for (i = 0; i < pcpu4k_nr_static_pages; i++) {
+ void *ptr;
+
+ ptr = alloc_fn(cpu, PAGE_SIZE);
+ if (!ptr) {
+ pr_warning("PERCPU: failed to allocate "
+ "4k page for cpu%u\n", cpu);
+ goto enomem;
+ }
+
+ memcpy(ptr, __per_cpu_load + i * PAGE_SIZE, PAGE_SIZE);
+ pcpu4k_pages[j++] = virt_to_page(ptr);
+ }
+
+ /* we're ready, commit */
+ pr_info("PERCPU: Allocated %d 4k pages, static data %zu bytes\n",
+ pcpu4k_nr_static_pages, static_size);
+
+ ret = pcpu_setup_first_chunk(pcpu4k_get_page, static_size,
+ reserved_size, -1,
+ -1, NULL, populate_pte_fn);
+ goto out_free_ar;
+
+enomem:
+ while (--j >= 0)
+ free_fn(page_address(pcpu4k_pages[j]), PAGE_SIZE);
+ ret = -ENOMEM;
+out_free_ar:
+ free_bootmem(__pa(pcpu4k_pages), pages_size);
+ return ret;
+}
+
+/*
* Generic percpu area setup.
*
* The embedding helper is used because its behavior closely resembles
--
1.6.0.2