diff options
| -rw-r--r-- | Documentation/kernel-parameters.txt | 6 | ||||
| -rw-r--r-- | arch/x86/kernel/setup_percpu.c | 69 | ||||
| -rw-r--r-- | mm/percpu.c | 13 |
3 files changed, 65 insertions, 23 deletions
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt index 08def8d..ecad946 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 bad2fd2..165ebd5 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 d06f474..b70f2ac 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) { |