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-rw-r--r--Documentation/kernel-parameters.txt6
-rw-r--r--arch/x86/kernel/setup_percpu.c69
-rw-r--r--mm/percpu.c13
3 files changed, 65 insertions, 23 deletions
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 08def8deb5f..ecad946920d 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -1882,6 +1882,12 @@ 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 "4k".
+ See comments in arch/x86/kernel/setup_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 bad2fd22311..165ebd5ba83 100644
--- a/arch/x86/kernel/setup_percpu.c
+++ b/arch/x86/kernel/setup_percpu.c
@@ -156,20 +156,23 @@ static struct page * __init pcpul_get_page(unsigned int cpu, int pageno)
return virt_to_page(pcpul_map[cpu].ptr + off);
}
-static ssize_t __init setup_pcpu_lpage(size_t static_size)
+static ssize_t __init setup_pcpu_lpage(size_t static_size, bool chosen)
{
size_t map_size, dyn_size;
unsigned int cpu;
int i, j;
ssize_t ret;
- /*
- * If large page isn't supported, there's no benefit in doing
- * this. Also, on non-NUMA, embedding is better.
- */
- if (!cpu_has_pse || !pcpu_need_numa())
+ /* on non-NUMA, embedding is better */
+ if (!chosen && !pcpu_need_numa())
return -EINVAL;
+ /* need PSE */
+ if (!cpu_has_pse) {
+ pr_warning("PERCPU: lpage allocator requires PSE\n");
+ return -EINVAL;
+ }
+
/*
* Currently supports only single page. Supporting multiple
* pages won't be too difficult if it ever becomes necessary.
@@ -191,8 +194,11 @@ static ssize_t __init setup_pcpu_lpage(size_t static_size)
pcpul_map[cpu].cpu = cpu;
pcpul_map[cpu].ptr = pcpu_alloc_bootmem(cpu, PMD_SIZE,
PMD_SIZE);
- if (!pcpul_map[cpu].ptr)
+ if (!pcpul_map[cpu].ptr) {
+ pr_warning("PERCPU: failed to allocate large page "
+ "for cpu%u\n", cpu);
goto enomem;
+ }
/*
* Only use pcpul_size bytes and give back the rest.
@@ -297,7 +303,7 @@ void *pcpu_lpage_remapped(void *kaddr)
return NULL;
}
#else
-static ssize_t __init setup_pcpu_lpage(size_t static_size)
+static ssize_t __init setup_pcpu_lpage(size_t static_size, bool chosen)
{
return -EINVAL;
}
@@ -311,7 +317,7 @@ static ssize_t __init setup_pcpu_lpage(size_t static_size)
* mapping so that it can use PMD mapping without additional TLB
* pressure.
*/
-static ssize_t __init setup_pcpu_embed(size_t static_size)
+static ssize_t __init setup_pcpu_embed(size_t static_size, bool chosen)
{
size_t reserve = PERCPU_MODULE_RESERVE + PERCPU_DYNAMIC_RESERVE;
@@ -320,7 +326,7 @@ static ssize_t __init setup_pcpu_embed(size_t static_size)
* this. Also, embedding allocation doesn't play well with
* NUMA.
*/
- if (!cpu_has_pse || pcpu_need_numa())
+ if (!chosen && (!cpu_has_pse || pcpu_need_numa()))
return -EINVAL;
return pcpu_embed_first_chunk(static_size, PERCPU_FIRST_CHUNK_RESERVE,
@@ -370,8 +376,11 @@ static ssize_t __init setup_pcpu_4k(size_t static_size)
void *ptr;
ptr = pcpu_alloc_bootmem(cpu, PAGE_SIZE, PAGE_SIZE);
- if (!ptr)
+ 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);
@@ -395,6 +404,16 @@ out_free_ar:
return ret;
}
+/* 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
@@ -408,11 +427,6 @@ static inline void setup_percpu_segment(int cpu)
#endif
}
-/*
- * Great future plan:
- * Declare PDA itself and support (irqstack,tss,pgd) as per cpu data.
- * Always point %gs to its beginning
- */
void __init setup_per_cpu_areas(void)
{
size_t static_size = __per_cpu_end - __per_cpu_start;
@@ -429,9 +443,26 @@ void __init setup_per_cpu_areas(void)
* of large page mappings. Please read comments on top of
* each allocator for details.
*/
- ret = setup_pcpu_lpage(static_size);
- if (ret < 0)
- ret = setup_pcpu_embed(static_size);
+ ret = -EINVAL;
+ if (strlen(pcpu_chosen_alloc)) {
+ if (strcmp(pcpu_chosen_alloc, "4k")) {
+ if (!strcmp(pcpu_chosen_alloc, "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);
+ if (ret < 0)
+ pr_warning("PERCPU: %s allocator failed (%zd), "
+ "falling back to 4k\n",
+ pcpu_chosen_alloc, ret);
+ }
+ } else {
+ ret = setup_pcpu_lpage(static_size, false);
+ if (ret < 0)
+ ret = setup_pcpu_embed(static_size, false);
+ }
if (ret < 0)
ret = setup_pcpu_4k(static_size);
if (ret < 0)
diff --git a/mm/percpu.c b/mm/percpu.c
index d06f4748271..b70f2acd885 100644
--- a/mm/percpu.c
+++ b/mm/percpu.c
@@ -1233,6 +1233,7 @@ static struct page * __init pcpue_get_page(unsigned int cpu, int pageno)
ssize_t __init pcpu_embed_first_chunk(size_t static_size, size_t reserved_size,
ssize_t dyn_size, ssize_t unit_size)
{
+ size_t chunk_size;
unsigned int cpu;
/* determine parameters and allocate */
@@ -1247,11 +1248,15 @@ ssize_t __init pcpu_embed_first_chunk(size_t static_size, size_t reserved_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)
+ chunk_size = pcpue_unit_size * num_possible_cpus();
+
+ pcpue_ptr = __alloc_bootmem_nopanic(chunk_size, PAGE_SIZE,
+ __pa(MAX_DMA_ADDRESS));
+ if (!pcpue_ptr) {
+ pr_warning("PERCPU: failed to allocate %zu bytes for "
+ "embedding\n", chunk_size);
return -ENOMEM;
+ }
/* return the leftover and copy */
for_each_possible_cpu(cpu) {