From 7df1027542c9353bef4d027cb4ab8e99f69017b7 Mon Sep 17 00:00:00 2001 From: Anton Blanchard Date: Wed, 23 Nov 2011 20:07:22 +0000 Subject: [PATCH] powerpc/time: Optimise decrementer_check_overflow decrementer_check_overflow is called from arch_local_irq_restore so we want to make it as light weight as possible. As such, turn decrementer_check_overflow into an inline function. To avoid a circular mess of includes, separate out the two components of struct decrementer_clock and keep the struct clock_event_device part local to time.c. The fast path improves from: arch_local_irq_restore 0: mflr r0 4: std r0,16(r1) 8: stdu r1,-112(r1) c: stb r3,578(r13) 10: cmpdi cr7,r3,0 14: beq- cr7,24 <.arch_local_irq_restore+0x24> ... 24: addi r1,r1,112 28: ld r0,16(r1) 2c: mtlr r0 30: blr to: arch_local_irq_restore 0: std r30,-16(r1) 4: ld r30,0(r2) 8: stb r3,578(r13) c: cmpdi cr7,r3,0 10: beq- cr7,6c <.arch_local_irq_restore+0x6c> ... 6c: ld r30,-16(r1) 70: blr Unfortunately we still setup a local TOC (due to -mminimal-toc). Yet another sign we should be moving to -mcmodel=medium. Signed-off-by: Anton Blanchard Signed-off-by: Benjamin Herrenschmidt --- arch/powerpc/include/asm/time.h | 2 +- arch/powerpc/kernel/irq.c | 9 +++++++++ arch/powerpc/kernel/time.c | 27 +++++++-------------------- 3 files changed, 17 insertions(+), 21 deletions(-) diff --git a/arch/powerpc/include/asm/time.h b/arch/powerpc/include/asm/time.h index bc3c745cb906..7eb10fb96cd0 100644 --- a/arch/powerpc/include/asm/time.h +++ b/arch/powerpc/include/asm/time.h @@ -219,7 +219,7 @@ DECLARE_PER_CPU(struct cpu_usage, cpu_usage_array); extern void secondary_cpu_time_init(void); extern void iSeries_time_init_early(void); -extern void decrementer_check_overflow(void); +DECLARE_PER_CPU(u64, decrementers_next_tb); #endif /* __KERNEL__ */ #endif /* __POWERPC_TIME_H */ diff --git a/arch/powerpc/kernel/irq.c b/arch/powerpc/kernel/irq.c index 745c1e7c10fd..2ff4f5e59620 100644 --- a/arch/powerpc/kernel/irq.c +++ b/arch/powerpc/kernel/irq.c @@ -115,6 +115,15 @@ static inline notrace void set_soft_enabled(unsigned long enable) : : "r" (enable), "i" (offsetof(struct paca_struct, soft_enabled))); } +static inline notrace void decrementer_check_overflow(void) +{ + u64 now = get_tb_or_rtc(); + u64 *next_tb = &__get_cpu_var(decrementers_next_tb); + + if (now >= *next_tb) + set_dec(1); +} + notrace void arch_local_irq_restore(unsigned long en) { /* diff --git a/arch/powerpc/kernel/time.c b/arch/powerpc/kernel/time.c index b1990b987e2c..9754743db8b9 100644 --- a/arch/powerpc/kernel/time.c +++ b/arch/powerpc/kernel/time.c @@ -114,12 +114,8 @@ static struct clock_event_device decrementer_clockevent = { .features = CLOCK_EVT_FEAT_ONESHOT, }; -struct decrementer_clock { - struct clock_event_device event; - u64 next_tb; -}; - -static DEFINE_PER_CPU(struct decrementer_clock, decrementers); +DEFINE_PER_CPU(u64, decrementers_next_tb); +static DEFINE_PER_CPU(struct clock_event_device, decrementers); #ifdef CONFIG_PPC_ISERIES static unsigned long __initdata iSeries_recal_titan; @@ -570,8 +566,8 @@ void arch_irq_work_raise(void) void timer_interrupt(struct pt_regs * regs) { struct pt_regs *old_regs; - struct decrementer_clock *decrementer = &__get_cpu_var(decrementers); - struct clock_event_device *evt = &decrementer->event; + u64 *next_tb = &__get_cpu_var(decrementers_next_tb); + struct clock_event_device *evt = &__get_cpu_var(decrementers); /* Ensure a positive value is written to the decrementer, or else * some CPUs will continue to take decrementer exceptions. @@ -606,7 +602,7 @@ void timer_interrupt(struct pt_regs * regs) get_lppaca()->int_dword.fields.decr_int = 0; #endif - decrementer->next_tb = ~(u64)0; + *next_tb = ~(u64)0; if (evt->event_handler) evt->event_handler(evt); @@ -872,19 +868,10 @@ static void __init clocksource_init(void) clock->name, clock->mult, clock->shift); } -void decrementer_check_overflow(void) -{ - u64 now = get_tb_or_rtc(); - struct decrementer_clock *decrementer = &__get_cpu_var(decrementers); - - if (now >= decrementer->next_tb) - set_dec(1); -} - static int decrementer_set_next_event(unsigned long evt, struct clock_event_device *dev) { - __get_cpu_var(decrementers).next_tb = get_tb_or_rtc() + evt; + __get_cpu_var(decrementers_next_tb) = get_tb_or_rtc() + evt; set_dec(evt); return 0; } @@ -898,7 +885,7 @@ static void decrementer_set_mode(enum clock_event_mode mode, static void register_decrementer_clockevent(int cpu) { - struct clock_event_device *dec = &per_cpu(decrementers, cpu).event; + struct clock_event_device *dec = &per_cpu(decrementers, cpu); *dec = decrementer_clockevent; dec->cpumask = cpumask_of(cpu); -- 2.20.1