[PATCH 4/5] percpu: generalize embedding first chunk setup helper

Tejun Heo
2009-03-10T07:57:34Z

Impact: code reorganization

Separate out embedding first chunk setup helper from x86 embedding
first chunk allocator and put it in mm/percpu.c. This will be used by
the default percpu first chunk allocator and possibly by other archs.

Signed-off-by: Tejun Heo <tj@kernel.org>
---
arch/x86/kernel/setup_percpu.c | 54 +++----------------------
include/linux/percpu.h | 4 ++
mm/percpu.c | 86 ++++++++++++++++++++++++++++++++++++++++
3 files changed, 96 insertions(+), 48 deletions(-)

diff --git a/arch/x86/kernel/setup_percpu.c b/arch/x86/kernel/setup_percpu.c
index e41c51f..400331b 100644
--- a/arch/x86/kernel/setup_percpu.c
+++ b/arch/x86/kernel/setup_percpu.c
@@ -257,31 +257,13 @@ static ssize_t __init setup_pcpu_remap(size_t static_size)
* Embedding allocator
*
* The first chunk is sized to just contain the static area plus
- * module and dynamic reserves, and allocated as a contiguous area
- * using bootmem allocator and used as-is without being mapped into
- * vmalloc area. This enables the first chunk to piggy back on the
- * linear physical PMD mapping and doesn't add any additional pressure
- * to TLB. Note that if the needed size is smaller than the minimum
- * unit size, the leftover is returned to the bootmem allocator.
+ * module and dynamic reserves and embedded into linear physical
+ * mapping so that it can use PMD mapping without additional TLB
+ * pressure.
*/
-static void *pcpue_ptr __initdata;
-static size_t pcpue_size __initdata;
-static size_t pcpue_unit_size __initdata;
-
-static struct page * __init pcpue_get_page(unsigned int cpu, int pageno)
-{
- size_t off = (size_t)pageno << PAGE_SHIFT;
-
- if (off >= pcpue_size)
- return NULL;
-
- return virt_to_page(pcpue_ptr + cpu * pcpue_unit_size + off);
-}
-
static ssize_t __init setup_pcpu_embed(size_t static_size)
{
- unsigned int cpu;
- size_t dyn_size;
+ size_t reserve = PERCPU_MODULE_RESERVE + PERCPU_DYNAMIC_RESERVE;

/*
* If large page isn't supported, there's no benefit in doing
@@ -291,32 +273,8 @@ static ssize_t __init setup_pcpu_embed(size_t static_size)
if (!cpu_has_pse || pcpu_need_numa())
return -EINVAL;

- /* allocate and copy */
- pcpue_size = PFN_ALIGN(static_size + PERCPU_MODULE_RESERVE +
- PERCPU_DYNAMIC_RESERVE);
- pcpue_unit_size = max_t(size_t, pcpue_size, PCPU_MIN_UNIT_SIZE);
- dyn_size = pcpue_size - static_size - PERCPU_FIRST_CHUNK_RESERVE;
-
- pcpue_ptr = pcpu_alloc_bootmem(0, num_possible_cpus() * pcpue_unit_size,
- PAGE_SIZE);
- if (!pcpue_ptr)
- return -ENOMEM;
-
- for_each_possible_cpu(cpu) {
- void *ptr = pcpue_ptr + cpu * pcpue_unit_size;
-
- free_bootmem(__pa(ptr + pcpue_size),
- pcpue_unit_size - pcpue_size);
- memcpy(ptr, __per_cpu_load, static_size);
- }
-
- /* we're ready, commit */
- pr_info("PERCPU: Embedded %zu pages at %p, static data %zu bytes\n",
- pcpue_size >> PAGE_SHIFT, pcpue_ptr, static_size);
-
- return pcpu_setup_first_chunk(pcpue_get_page, static_size,
- PERCPU_FIRST_CHUNK_RESERVE, dyn_size,
- pcpue_unit_size, pcpue_ptr, NULL);
+ return pcpu_embed_first_chunk(static_size, PERCPU_FIRST_CHUNK_RESERVE,
+ reserve - PERCPU_FIRST_CHUNK_RESERVE, -1);
}

/*
diff --git a/include/linux/percpu.h b/include/linux/percpu.h
index fb455dc..ee5615d 100644
--- a/include/linux/percpu.h
+++ b/include/linux/percpu.h
@@ -111,6 +111,10 @@ extern size_t __init pcpu_setup_first_chunk(pcpu_get_page_fn_t get_page_fn,
void *base_addr,
pcpu_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, ssize_t unit_size);
+
/*
* 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 2f94661..1aa5d8f 100644
--- a/mm/percpu.c
+++ b/mm/percpu.c
@@ -1238,3 +1238,89 @@ size_t __init pcpu_setup_first_chunk(pcpu_get_page_fn_t get_page_fn,
pcpu_base_addr = (void *)pcpu_chunk_addr(schunk, 0, 0);
return pcpu_unit_size;
}
+
+/*
+ * Embedding first chunk setup helper.
+ */
+static void *pcpue_ptr __initdata;
+static size_t pcpue_size __initdata;
+static size_t pcpue_unit_size __initdata;
+
+static struct page * __init pcpue_get_page(unsigned int cpu, int pageno)
+{
+ size_t off = (size_t)pageno << PAGE_SHIFT;
+
+ if (off >= pcpue_size)
+ return NULL;
+
+ return virt_to_page(pcpue_ptr + cpu * pcpue_unit_size + off);
+}
+
+/**
+ * pcpu_embed_first_chunk - embed the first percpu chunk into bootmem
+ * @static_size: the size of static percpu area in bytes
+ * @reserved_size: the size of reserved percpu area in bytes
+ * @dyn_size: free size for dynamic allocation in bytes, -1 for auto
+ * @unit_size: unit size in bytes, must be multiple of PAGE_SIZE, -1 for auto
+ *
+ * This is a helper to ease setting up embedded first percpu chunk and
+ * can be called where pcpu_setup_first_chunk() is expected.
+ *
+ * If this function is used to setup the first chunk, it is allocated
+ * as a contiguous area using bootmem allocator and used as-is without
+ * being mapped into vmalloc area. This enables the first chunk to
+ * piggy back on the linear physical mapping which often uses larger
+ * page size.
+ *
+ * When @dyn_size is positive, dynamic area might be larger than
+ * specified to fill page alignment. Also, when @dyn_size is auto,
+ * @dyn_size does not fill the whole first chunk but only what's
+ * necessary for page alignment after static and reserved areas.
+ *
+ * If the needed size is smaller than the minimum or specified unit
+ * size, the leftover is returned to the bootmem allocator.
+ *
+ * RETURNS:
+ * The determined pcpu_unit_size which can be used to initialize
+ * percpu access on success, -errno on failure.
+ */
+ssize_t __init pcpu_embed_first_chunk(size_t static_size, size_t reserved_size,
+ ssize_t dyn_size, ssize_t unit_size)
+{
+ unsigned int cpu;
+
+ /* determine parameters and allocate */
+ pcpue_size = PFN_ALIGN(static_size + reserved_size +
+ (dyn_size >= 0 ? dyn_size : 0));
+ if (dyn_size != 0)
+ dyn_size = pcpue_size - static_size - reserved_size;
+
+ if (unit_size >= 0) {
+ BUG_ON(unit_size < pcpue_size);
+ pcpue_unit_size = unit_size;
+ } else
+ pcpue_unit_size = max_t(size_t, pcpue_size, PCPU_MIN_UNIT_SIZE);
+
+ pcpue_ptr = __alloc_bootmem_nopanic(
+ num_possible_cpus() * pcpue_unit_size,
+ PAGE_SIZE, __pa(MAX_DMA_ADDRESS));
+ if (!pcpue_ptr)
+ return -ENOMEM;
+
+ /* return the leftover and copy */
+ for_each_possible_cpu(cpu) {
+ void *ptr = pcpue_ptr + cpu * pcpue_unit_size;
+
+ free_bootmem(__pa(ptr + pcpue_size),
+ pcpue_unit_size - pcpue_size);
+ memcpy(ptr, __per_cpu_load, static_size);
+ }
+
+ /* we're ready, commit */
+ pr_info("PERCPU: Embedded %zu pages at %p, static data %zu bytes\n",
+ pcpue_size >> PAGE_SHIFT, pcpue_ptr, static_size);
+
+ return pcpu_setup_first_chunk(pcpue_get_page, static_size,
+ reserved_size, dyn_size,
+ pcpue_unit_size, pcpue_ptr, NULL);
+}
--
1.6.0.2