From 2f859d0dad818765117c1cecb24b3bc7f4592074 Mon Sep 17 00:00:00 2001 From: Heiko Carstens Date: Wed, 11 Feb 2015 12:31:03 +0100 Subject: [PATCH] s390/smp: reduce size of struct pcpu Reduce the size of struct pcpu, since the pcpu_devices array consists of NR_CPUS elements of type struct pcpu. For most machines this is just a waste of memory. So let's try to make it a bit smaller. This saves 16k with performance_defconfig. Signed-off-by: Heiko Carstens Signed-off-by: Martin Schwidefsky --- arch/s390/kernel/smp.c | 54 +++++++++++++++++++++--------------------- 1 file changed, 27 insertions(+), 27 deletions(-) diff --git a/arch/s390/kernel/smp.c b/arch/s390/kernel/smp.c index a668993ff577..db8f1115a3bf 100644 --- a/arch/s390/kernel/smp.c +++ b/arch/s390/kernel/smp.c @@ -59,14 +59,13 @@ enum { CPU_STATE_CONFIGURED, }; +static DEFINE_PER_CPU(struct cpu *, cpu_device); + struct pcpu { - struct cpu *cpu; struct _lowcore *lowcore; /* lowcore page(s) for the cpu */ - unsigned long async_stack; /* async stack for the cpu */ - unsigned long panic_stack; /* panic stack for the cpu */ unsigned long ec_mask; /* bit mask for ec_xxx functions */ - int state; /* physical cpu state */ - int polarization; /* physical polarization */ + signed char state; /* physical cpu state */ + signed char polarization; /* physical polarization */ u16 address; /* physical cpu address */ }; @@ -173,25 +172,30 @@ static void pcpu_ec_call(struct pcpu *pcpu, int ec_bit) pcpu_sigp_retry(pcpu, order, 0); } +#define ASYNC_FRAME_OFFSET (ASYNC_SIZE - STACK_FRAME_OVERHEAD - __PT_SIZE) +#define PANIC_FRAME_OFFSET (PAGE_SIZE - STACK_FRAME_OVERHEAD - __PT_SIZE) + static int pcpu_alloc_lowcore(struct pcpu *pcpu, int cpu) { + unsigned long async_stack, panic_stack; struct _lowcore *lc; if (pcpu != &pcpu_devices[0]) { pcpu->lowcore = (struct _lowcore *) __get_free_pages(GFP_KERNEL | GFP_DMA, LC_ORDER); - pcpu->async_stack = __get_free_pages(GFP_KERNEL, ASYNC_ORDER); - pcpu->panic_stack = __get_free_page(GFP_KERNEL); - if (!pcpu->lowcore || !pcpu->panic_stack || !pcpu->async_stack) + async_stack = __get_free_pages(GFP_KERNEL, ASYNC_ORDER); + panic_stack = __get_free_page(GFP_KERNEL); + if (!pcpu->lowcore || !panic_stack || !async_stack) goto out; + } else { + async_stack = pcpu->lowcore->async_stack - ASYNC_FRAME_OFFSET; + panic_stack = pcpu->lowcore->panic_stack - PANIC_FRAME_OFFSET; } lc = pcpu->lowcore; memcpy(lc, &S390_lowcore, 512); memset((char *) lc + 512, 0, sizeof(*lc) - 512); - lc->async_stack = pcpu->async_stack + ASYNC_SIZE - - STACK_FRAME_OVERHEAD - sizeof(struct pt_regs); - lc->panic_stack = pcpu->panic_stack + PAGE_SIZE - - STACK_FRAME_OVERHEAD - sizeof(struct pt_regs); + lc->async_stack = async_stack + ASYNC_FRAME_OFFSET; + lc->panic_stack = panic_stack + PANIC_FRAME_OFFSET; lc->cpu_nr = cpu; lc->spinlock_lockval = arch_spin_lockval(cpu); #ifndef CONFIG_64BIT @@ -212,8 +216,8 @@ static int pcpu_alloc_lowcore(struct pcpu *pcpu, int cpu) return 0; out: if (pcpu != &pcpu_devices[0]) { - free_page(pcpu->panic_stack); - free_pages(pcpu->async_stack, ASYNC_ORDER); + free_page(panic_stack); + free_pages(async_stack, ASYNC_ORDER); free_pages((unsigned long) pcpu->lowcore, LC_ORDER); } return -ENOMEM; @@ -235,11 +239,11 @@ static void pcpu_free_lowcore(struct pcpu *pcpu) #else vdso_free_per_cpu(pcpu->lowcore); #endif - if (pcpu != &pcpu_devices[0]) { - free_page(pcpu->panic_stack); - free_pages(pcpu->async_stack, ASYNC_ORDER); - free_pages((unsigned long) pcpu->lowcore, LC_ORDER); - } + if (pcpu == &pcpu_devices[0]) + return; + free_page(pcpu->lowcore->panic_stack-PANIC_FRAME_OFFSET); + free_pages(pcpu->lowcore->async_stack-ASYNC_FRAME_OFFSET, ASYNC_ORDER); + free_pages((unsigned long) pcpu->lowcore, LC_ORDER); } #endif /* CONFIG_HOTPLUG_CPU */ @@ -366,7 +370,8 @@ void smp_call_online_cpu(void (*func)(void *), void *data) void smp_call_ipl_cpu(void (*func)(void *), void *data) { pcpu_delegate(&pcpu_devices[0], func, data, - pcpu_devices->panic_stack + PAGE_SIZE); + pcpu_devices->lowcore->panic_stack - + PANIC_FRAME_OFFSET + PAGE_SIZE); } int smp_find_processor_id(u16 address) @@ -935,10 +940,6 @@ void __init smp_prepare_boot_cpu(void) pcpu->state = CPU_STATE_CONFIGURED; pcpu->address = stap(); pcpu->lowcore = (struct _lowcore *)(unsigned long) store_prefix(); - pcpu->async_stack = S390_lowcore.async_stack - ASYNC_SIZE - + STACK_FRAME_OVERHEAD + sizeof(struct pt_regs); - pcpu->panic_stack = S390_lowcore.panic_stack - PAGE_SIZE - + STACK_FRAME_OVERHEAD + sizeof(struct pt_regs); S390_lowcore.percpu_offset = __per_cpu_offset[0]; smp_cpu_set_polarization(0, POLARIZATION_UNKNOWN); set_cpu_present(0, true); @@ -1078,8 +1079,7 @@ static int smp_cpu_notify(struct notifier_block *self, unsigned long action, void *hcpu) { unsigned int cpu = (unsigned int)(long)hcpu; - struct cpu *c = pcpu_devices[cpu].cpu; - struct device *s = &c->dev; + struct device *s = &per_cpu(cpu_device, cpu)->dev; int err = 0; switch (action & ~CPU_TASKS_FROZEN) { @@ -1102,7 +1102,7 @@ static int smp_add_present_cpu(int cpu) c = kzalloc(sizeof(*c), GFP_KERNEL); if (!c) return -ENOMEM; - pcpu_devices[cpu].cpu = c; + per_cpu(cpu_device, cpu) = c; s = &c->dev; c->hotpluggable = 1; rc = register_cpu(c, cpu); -- 2.20.1