From 1cb6bb4bbdfd7b6bbdd148c4a34c02066339806d Mon Sep 17 00:00:00 2001 From: Heiko Carstens Date: Sat, 26 Jan 2008 14:11:14 +0100 Subject: [PATCH] [S390] Allocate and free cpu lowcores and stacks when needed/possible. No need to preallocate the per cpu lowcores and stacks. Savings are 28-32k per offline cpu. Signed-off-by: Heiko Carstens Signed-off-by: Martin Schwidefsky --- arch/s390/kernel/smp.c | 106 ++++++++++++++++++++++++++++------------- 1 file changed, 72 insertions(+), 34 deletions(-) diff --git a/arch/s390/kernel/smp.c b/arch/s390/kernel/smp.c index d300a7fdf7..040406dbe9 100644 --- a/arch/s390/kernel/smp.c +++ b/arch/s390/kernel/smp.c @@ -589,8 +589,72 @@ static void __init smp_create_idle(unsigned int cpu) spin_lock_init(&(&per_cpu(s390_idle, cpu))->lock); } +static int __cpuinit smp_alloc_lowcore(int cpu) +{ + unsigned long async_stack, panic_stack; + struct _lowcore *lowcore; + int lc_order; + + lc_order = sizeof(long) == 8 ? 1 : 0; + lowcore = (void *) __get_free_pages(GFP_KERNEL | GFP_DMA, lc_order); + if (!lowcore) + return -ENOMEM; + async_stack = __get_free_pages(GFP_KERNEL, ASYNC_ORDER); + if (!async_stack) + goto out_async_stack; + panic_stack = __get_free_page(GFP_KERNEL); + if (!panic_stack) + goto out_panic_stack; + + *lowcore = S390_lowcore; + lowcore->async_stack = async_stack + ASYNC_SIZE; + lowcore->panic_stack = panic_stack + PAGE_SIZE; + +#ifndef CONFIG_64BIT + if (MACHINE_HAS_IEEE) { + unsigned long save_area; + + save_area = get_zeroed_page(GFP_KERNEL); + if (!save_area) + goto out_save_area; + lowcore->extended_save_area_addr = (u32) save_area; + } +#endif + lowcore_ptr[cpu] = lowcore; + return 0; + +#ifndef CONFIG_64BIT +out_save_area: + free_page(panic_stack); +#endif +out_panic_stack: + free_pages(async_stack, ASYNC_ORDER); +out_async_stack: + free_pages((unsigned long) lowcore, lc_order); + return -ENOMEM; +} + +#ifdef CONFIG_HOTPLUG_CPU +static void smp_free_lowcore(int cpu) +{ + struct _lowcore *lowcore; + int lc_order; + + lc_order = sizeof(long) == 8 ? 1 : 0; + lowcore = lowcore_ptr[cpu]; +#ifndef CONFIG_64BIT + if (MACHINE_HAS_IEEE) + free_page((unsigned long) lowcore->extended_save_area_addr); +#endif + free_page(lowcore->panic_stack - PAGE_SIZE); + free_pages(lowcore->async_stack - ASYNC_SIZE, ASYNC_ORDER); + free_pages((unsigned long) lowcore, lc_order); + lowcore_ptr[cpu] = NULL; +} +#endif /* CONFIG_HOTPLUG_CPU */ + /* Upping and downing of CPUs */ -int __cpu_up(unsigned int cpu) +int __cpuinit __cpu_up(unsigned int cpu) { struct task_struct *idle; struct _lowcore *cpu_lowcore; @@ -599,6 +663,8 @@ int __cpu_up(unsigned int cpu) if (smp_cpu_state[cpu] != CPU_STATE_CONFIGURED) return -EIO; + if (smp_alloc_lowcore(cpu)) + return -ENOMEM; ccode = signal_processor_p((__u32)(unsigned long)(lowcore_ptr[cpu]), cpu, sigp_set_prefix); @@ -613,6 +679,7 @@ int __cpu_up(unsigned int cpu) cpu_lowcore = lowcore_ptr[cpu]; cpu_lowcore->kernel_stack = (unsigned long) task_stack_page(idle) + THREAD_SIZE; + cpu_lowcore->thread_info = (unsigned long) task_thread_info(idle); sf = (struct stack_frame *) (cpu_lowcore->kernel_stack - sizeof(struct pt_regs) - sizeof(struct stack_frame)); @@ -626,6 +693,8 @@ int __cpu_up(unsigned int cpu) cpu_lowcore->percpu_offset = __per_cpu_offset[cpu]; cpu_lowcore->current_task = (unsigned long) idle; cpu_lowcore->cpu_data.cpu_nr = cpu; + cpu_lowcore->softirq_pending = 0; + cpu_lowcore->ext_call_fast = 0; eieio(); while (signal_processor(cpu, sigp_restart) == sigp_busy) @@ -686,6 +755,7 @@ void __cpu_die(unsigned int cpu) /* Wait until target cpu is down */ while (!smp_cpu_not_running(cpu)) cpu_relax(); + smp_free_lowcore(cpu); printk(KERN_INFO "Processor %d spun down\n", cpu); } @@ -699,15 +769,9 @@ void cpu_die(void) #endif /* CONFIG_HOTPLUG_CPU */ -/* - * Cycle through the processors and setup structures. - */ - void __init smp_prepare_cpus(unsigned int max_cpus) { - unsigned long stack; unsigned int cpu; - int i; smp_detect_cpus(); @@ -715,35 +779,9 @@ void __init smp_prepare_cpus(unsigned int max_cpus) if (register_external_interrupt(0x1201, do_ext_call_interrupt) != 0) panic("Couldn't request external interrupt 0x1201"); memset(lowcore_ptr, 0, sizeof(lowcore_ptr)); - /* - * Initialize prefix pages and stacks for all possible cpus - */ print_cpu_info(&S390_lowcore.cpu_data); + smp_alloc_lowcore(smp_processor_id()); - for_each_possible_cpu(i) { - lowcore_ptr[i] = (struct _lowcore *) - __get_free_pages(GFP_KERNEL | GFP_DMA, - sizeof(void*) == 8 ? 1 : 0); - stack = __get_free_pages(GFP_KERNEL, ASYNC_ORDER); - if (!lowcore_ptr[i] || !stack) - panic("smp_boot_cpus failed to allocate memory\n"); - - *(lowcore_ptr[i]) = S390_lowcore; - lowcore_ptr[i]->async_stack = stack + ASYNC_SIZE; - stack = __get_free_pages(GFP_KERNEL, 0); - if (!stack) - panic("smp_boot_cpus failed to allocate memory\n"); - lowcore_ptr[i]->panic_stack = stack + PAGE_SIZE; -#ifndef CONFIG_64BIT - if (MACHINE_HAS_IEEE) { - lowcore_ptr[i]->extended_save_area_addr = - (__u32) __get_free_pages(GFP_KERNEL, 0); - if (!lowcore_ptr[i]->extended_save_area_addr) - panic("smp_boot_cpus failed to " - "allocate memory\n"); - } -#endif - } #ifndef CONFIG_64BIT if (MACHINE_HAS_IEEE) ctl_set_bit(14, 29); /* enable extended save area */ -- 2.39.5