diff options
Diffstat (limited to 'arch/x86_64/kernel/smp.c')
| -rw-r--r-- | arch/x86_64/kernel/smp.c | 129 |
1 files changed, 82 insertions, 47 deletions
diff --git a/arch/x86_64/kernel/smp.c b/arch/x86_64/kernel/smp.c index e5958220d6b..9db9dda161b 100644 --- a/arch/x86_64/kernel/smp.c +++ b/arch/x86_64/kernel/smp.c @@ -12,7 +12,6 @@ #include <linux/init.h> #include <linux/mm.h> -#include <linux/irq.h> #include <linux/delay.h> #include <linux/spinlock.h> #include <linux/smp_lock.h> @@ -29,6 +28,8 @@ #include <asm/proto.h> #include <asm/apicdef.h> +#define __cpuinit __init + /* * Smarter SMP flushing macros. * c/o Linus Torvalds. @@ -37,19 +38,41 @@ * writing to user space from interrupts. (Its not allowed anyway). * * Optimizations Manfred Spraul <manfred@colorfullife.com> + * + * More scalable flush, from Andi Kleen + * + * To avoid global state use 8 different call vectors. + * Each CPU uses a specific vector to trigger flushes on other + * CPUs. Depending on the received vector the target CPUs look into + * the right per cpu variable for the flush data. + * + * With more than 8 CPUs they are hashed to the 8 available + * vectors. The limited global vector space forces us to this right now. + * In future when interrupts are split into per CPU domains this could be + * fixed, at the cost of triggering multiple IPIs in some cases. */ -static cpumask_t flush_cpumask; -static struct mm_struct * flush_mm; -static unsigned long flush_va; -static DEFINE_SPINLOCK(tlbstate_lock); +union smp_flush_state { + struct { + cpumask_t flush_cpumask; + struct mm_struct *flush_mm; + unsigned long flush_va; #define FLUSH_ALL -1ULL + spinlock_t tlbstate_lock; + }; + char pad[SMP_CACHE_BYTES]; +} ____cacheline_aligned; + +/* State is put into the per CPU data section, but padded + to a full cache line because other CPUs can access it and we don't + want false sharing in the per cpu data segment. */ +static DEFINE_PER_CPU(union smp_flush_state, flush_state); /* * We cannot call mmdrop() because we are in interrupt context, * instead update mm->cpu_vm_mask. */ -static inline void leave_mm (unsigned long cpu) +static inline void leave_mm(int cpu) { if (read_pda(mmu_state) == TLBSTATE_OK) BUG(); @@ -101,15 +124,25 @@ static inline void leave_mm (unsigned long cpu) * * 1) Flush the tlb entries if the cpu uses the mm that's being flushed. * 2) Leave the mm if we are in the lazy tlb mode. + * + * Interrupts are disabled. */ -asmlinkage void smp_invalidate_interrupt (void) +asmlinkage void smp_invalidate_interrupt(struct pt_regs *regs) { - unsigned long cpu; + int cpu; + int sender; + union smp_flush_state *f; - cpu = get_cpu(); + cpu = smp_processor_id(); + /* + * orig_rax contains the interrupt vector - 256. + * Use that to determine where the sender put the data. + */ + sender = regs->orig_rax + 256 - INVALIDATE_TLB_VECTOR_START; + f = &per_cpu(flush_state, sender); - if (!cpu_isset(cpu, flush_cpumask)) + if (!cpu_isset(cpu, f->flush_cpumask)) goto out; /* * This was a BUG() but until someone can quote me the @@ -120,64 +153,63 @@ asmlinkage void smp_invalidate_interrupt (void) * BUG(); */ - if (flush_mm == read_pda(active_mm)) { + if (f->flush_mm == read_pda(active_mm)) { if (read_pda(mmu_state) == TLBSTATE_OK) { - if (flush_va == FLUSH_ALL) + if (f->flush_va == FLUSH_ALL) local_flush_tlb(); else - __flush_tlb_one(flush_va); + __flush_tlb_one(f->flush_va); } else leave_mm(cpu); } out: ack_APIC_irq(); - cpu_clear(cpu, flush_cpumask); - put_cpu_no_resched(); + cpu_clear(cpu, f->flush_cpumask); } static void flush_tlb_others(cpumask_t cpumask, struct mm_struct *mm, unsigned long va) { - cpumask_t tmp; - /* - * A couple of (to be removed) sanity checks: - * - * - we do not send IPIs to not-yet booted CPUs. - * - current CPU must not be in mask - * - mask must exist :) - */ - BUG_ON(cpus_empty(cpumask)); - cpus_and(tmp, cpumask, cpu_online_map); - BUG_ON(!cpus_equal(tmp, cpumask)); - BUG_ON(cpu_isset(smp_processor_id(), cpumask)); - if (!mm) - BUG(); + int sender; + union smp_flush_state *f; - /* - * I'm not happy about this global shared spinlock in the - * MM hot path, but we'll see how contended it is. - * Temporarily this turns IRQs off, so that lockups are - * detected by the NMI watchdog. - */ - spin_lock(&tlbstate_lock); - - flush_mm = mm; - flush_va = va; - cpus_or(flush_cpumask, cpumask, flush_cpumask); + /* Caller has disabled preemption */ + sender = smp_processor_id() % NUM_INVALIDATE_TLB_VECTORS; + f = &per_cpu(flush_state, sender); + + /* Could avoid this lock when + num_online_cpus() <= NUM_INVALIDATE_TLB_VECTORS, but it is + probably not worth checking this for a cache-hot lock. */ + spin_lock(&f->tlbstate_lock); + + f->flush_mm = mm; + f->flush_va = va; + cpus_or(f->flush_cpumask, cpumask, f->flush_cpumask); /* * We have to send the IPI only to * CPUs affected. */ - send_IPI_mask(cpumask, INVALIDATE_TLB_VECTOR); + send_IPI_mask(cpumask, INVALIDATE_TLB_VECTOR_START + sender); + + while (!cpus_empty(f->flush_cpumask)) + cpu_relax(); - while (!cpus_empty(flush_cpumask)) - mb(); /* nothing. lockup detection does not belong here */; + f->flush_mm = NULL; + f->flush_va = 0; + spin_unlock(&f->tlbstate_lock); +} - flush_mm = NULL; - flush_va = 0; - spin_unlock(&tlbstate_lock); +int __cpuinit init_smp_flush(void) +{ + int i; + for_each_cpu_mask(i, cpu_possible_map) { + spin_lock_init(&per_cpu(flush_state.tlbstate_lock, i)); + } + return 0; } + +core_initcall(init_smp_flush); void flush_tlb_current_task(void) { @@ -295,8 +327,11 @@ void unlock_ipi_call_lock(void) /* * this function sends a 'generic call function' IPI to one other CPU * in the system. + * + * cpu is a standard Linux logical CPU number. */ -static void __smp_call_function_single (int cpu, void (*func) (void *info), void *info, +static void +__smp_call_function_single(int cpu, void (*func) (void *info), void *info, int nonatomic, int wait) { struct call_data_struct data; |