[PATCH 05/20] percpu: generalize first chunk allocator selection

Tejun Heo
2009-07-21T10:26:04Z

Now that all first chunk allocators are in mm/percpu.c, it makes sense
to make generalize percpu_alloc kernel parameter. Define PCPU_FC_*
and set pcpu_chosen_fc using early_param() in mm/percpu.c. Arch code
can use the set value to determine which first chunk allocator to use.

Signed-off-by: Tejun Heo <tj@kernel.org>
---
Documentation/kernel-parameters.txt | 11 ++++++-----
arch/x86/kernel/setup_percpu.c | 24 ++++++------------------
include/linux/percpu.h | 12 ++++++++++++
mm/percpu.c | 32 ++++++++++++++++++++++++++++++++
4 files changed, 56 insertions(+), 23 deletions(-)

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index faa7178..89b7568 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -1915,11 +1915,12 @@ and is between 256 and 4096 characters. It is defined in the file
Format: { 0 | 1 }
See arch/parisc/kernel/pdc_chassis.c

- percpu_alloc= [X86] Select which percpu first chunk allocator to use.
- Allowed values are one of "lpage", "embed" and "page".
- See comments in arch/x86/kernel/setup_percpu.c for
- details on each allocator. This parameter is primarily
- for debugging and performance comparison.
+ percpu_alloc= Select which percpu first chunk allocator to use.
+ Currently supported values are "embed", "page" and
+ "lpage". Archs may support subset or none of the
+ selections. See comments in mm/percpu.c for details
+ on each allocator. This parameter is primarily for
+ debugging and performance comparison.

pf. [PARIDE]
See Documentation/blockdev/paride.txt.
diff --git a/arch/x86/kernel/setup_percpu.c b/arch/x86/kernel/setup_percpu.c
index 3c943b4..7f1e09b 100644
--- a/arch/x86/kernel/setup_percpu.c
+++ b/arch/x86/kernel/setup_percpu.c
@@ -267,16 +267,6 @@ static ssize_t __init setup_pcpu_page(size_t static_size)
pcpup_populate_pte);
}

-/* for explicit first chunk allocator selection */
-static char pcpu_chosen_alloc[16] __initdata;
-
-static int __init percpu_alloc_setup(char *str)
-{
- strncpy(pcpu_chosen_alloc, str, sizeof(pcpu_chosen_alloc) - 1);
- return 0;
-}
-early_param("percpu_alloc", percpu_alloc_setup);
-
static inline void setup_percpu_segment(int cpu)
{
#ifdef CONFIG_X86_32
@@ -307,19 +297,17 @@ void __init setup_per_cpu_areas(void)
* each allocator for details.
*/
ret = -EINVAL;
- if (strlen(pcpu_chosen_alloc)) {
- if (strcmp(pcpu_chosen_alloc, "page")) {
- if (!strcmp(pcpu_chosen_alloc, "lpage"))
+ if (pcpu_chosen_fc != PCPU_FC_AUTO) {
+ if (pcpu_chosen_fc != PCPU_FC_PAGE) {
+ if (pcpu_chosen_fc == PCPU_FC_LPAGE)
ret = setup_pcpu_lpage(static_size, true);
- else if (!strcmp(pcpu_chosen_alloc, "embed"))
- ret = setup_pcpu_embed(static_size, true);
else
- pr_warning("PERCPU: unknown allocator %s "
- "specified\n", pcpu_chosen_alloc);
+ ret = setup_pcpu_embed(static_size, true);
+
if (ret < 0)
pr_warning("PERCPU: %s allocator failed (%zd), "
"falling back to page\n",
- pcpu_chosen_alloc, ret);
+ pcpu_fc_names[pcpu_chosen_fc], ret);
}
} else {
ret = setup_pcpu_lpage(static_size, false);
diff --git a/include/linux/percpu.h b/include/linux/percpu.h
index e26788e..9be05cb 100644
--- a/include/linux/percpu.h
+++ b/include/linux/percpu.h
@@ -59,6 +59,18 @@
extern void *pcpu_base_addr;
extern const int *pcpu_unit_map;

+enum pcpu_fc {
+ PCPU_FC_AUTO,
+ PCPU_FC_EMBED,
+ PCPU_FC_PAGE,
+ PCPU_FC_LPAGE,
+
+ PCPU_FC_NR,
+};
+extern const char *pcpu_fc_names[PCPU_FC_NR];
+
+extern enum pcpu_fc pcpu_chosen_fc;
+
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);
diff --git a/mm/percpu.c b/mm/percpu.c
index 4d926d3..6617020 100644
--- a/mm/percpu.c
+++ b/mm/percpu.c
@@ -1414,6 +1414,38 @@ size_t __init pcpu_setup_first_chunk(size_t static_size, size_t reserved_size,
return pcpu_unit_size;
}

+const char *pcpu_fc_names[PCPU_FC_NR] __initdata = {
+ [PCPU_FC_AUTO] = "auto",
+ [PCPU_FC_EMBED] = "embed",
+ [PCPU_FC_PAGE] = "page",
+ [PCPU_FC_LPAGE] = "lpage",
+};
+
+enum pcpu_fc pcpu_chosen_fc __initdata = PCPU_FC_AUTO;
+
+static int __init percpu_alloc_setup(char *str)
+{
+ if (0)
+ /* nada */;
+#ifdef CONFIG_NEED_PER_CPU_EMBED_FIRST_CHUNK
+ else if (!strcmp(str, "embed"))
+ pcpu_chosen_fc = PCPU_FC_EMBED;
+#endif
+#ifdef CONFIG_NEED_PER_CPU_PAGE_FIRST_CHUNK
+ else if (!strcmp(str, "page"))
+ pcpu_chosen_fc = PCPU_FC_PAGE;
+#endif
+#ifdef CONFIG_NEED_PER_CPU_LPAGE_FIRST_CHUNK
+ else if (!strcmp(str, "lpage"))
+ pcpu_chosen_fc = PCPU_FC_LPAGE;
+#endif
+ else
+ pr_warning("PERCPU: unknown allocator %s specified\n", str);
+
+ return 0;
+}
+early_param("percpu_alloc", percpu_alloc_setup);
+
static inline size_t pcpu_calc_fc_sizes(size_t static_size,
size_t reserved_size,
ssize_t *dyn_sizep)
--
1.6.0.2