From 43858b4f25cf0adc5c2ca9cf5ce5fdf2532941e5 Mon Sep 17 00:00:00 2001 From: Andy Lutomirski Date: Thu, 29 Jun 2017 08:53:18 -0700 Subject: [PATCH] x86/mm: Stop calling leave_mm() in idle code Now that lazy TLB suppresses all flush IPIs (as opposed to all but the first), there's no need to leave_mm() when going idle. This means we can get rid of the rcuidle hack in switch_mm_irqs_off() and we can unexport leave_mm(). This also removes acpi_unlazy_tlb() from the x86 and ia64 headers, since it has no callers any more. Signed-off-by: Andy Lutomirski Reviewed-by: Nadav Amit Reviewed-by: Borislav Petkov Reviewed-by: Thomas Gleixner Cc: Andrew Morton Cc: Arjan van de Ven Cc: Borislav Petkov Cc: Dave Hansen Cc: Linus Torvalds Cc: Mel Gorman Cc: Peter Zijlstra Cc: Rik van Riel Cc: linux-mm@kvack.org Link: http://lkml.kernel.org/r/03c699cfd6021e467be650d6b73deaccfe4b4bd7.1498751203.git.luto@kernel.org Signed-off-by: Ingo Molnar --- arch/ia64/include/asm/acpi.h | 2 -- arch/x86/include/asm/acpi.h | 2 -- arch/x86/mm/tlb.c | 20 +++----------------- drivers/acpi/processor_idle.c | 2 -- drivers/idle/intel_idle.c | 9 ++++----- 5 files changed, 7 insertions(+), 28 deletions(-) diff --git a/arch/ia64/include/asm/acpi.h b/arch/ia64/include/asm/acpi.h index a3d0211970e9..c86a947f5368 100644 --- a/arch/ia64/include/asm/acpi.h +++ b/arch/ia64/include/asm/acpi.h @@ -112,8 +112,6 @@ static inline void arch_acpi_set_pdc_bits(u32 *buf) buf[2] |= ACPI_PDC_EST_CAPABILITY_SMP; } -#define acpi_unlazy_tlb(x) - #ifdef CONFIG_ACPI_NUMA extern cpumask_t early_cpu_possible_map; #define for_each_possible_early_cpu(cpu) \ diff --git a/arch/x86/include/asm/acpi.h b/arch/x86/include/asm/acpi.h index 2efc768e4362..562286fa151f 100644 --- a/arch/x86/include/asm/acpi.h +++ b/arch/x86/include/asm/acpi.h @@ -150,8 +150,6 @@ static inline void disable_acpi(void) { } extern int x86_acpi_numa_init(void); #endif /* CONFIG_ACPI_NUMA */ -#define acpi_unlazy_tlb(x) leave_mm(x) - #ifdef CONFIG_ACPI_APEI static inline pgprot_t arch_apei_get_mem_attribute(phys_addr_t addr) { diff --git a/arch/x86/mm/tlb.c b/arch/x86/mm/tlb.c index 0982c997d36f..2c1b8881e9d3 100644 --- a/arch/x86/mm/tlb.c +++ b/arch/x86/mm/tlb.c @@ -50,7 +50,6 @@ void leave_mm(int cpu) switch_mm(NULL, &init_mm, NULL); } -EXPORT_SYMBOL_GPL(leave_mm); void switch_mm(struct mm_struct *prev, struct mm_struct *next, struct task_struct *tsk) @@ -117,15 +116,8 @@ void switch_mm_irqs_off(struct mm_struct *prev, struct mm_struct *next, this_cpu_write(cpu_tlbstate.ctxs[0].tlb_gen, next_tlb_gen); write_cr3(__pa(next->pgd)); - - /* - * This gets called via leave_mm() in the idle path - * where RCU functions differently. Tracing normally - * uses RCU, so we have to call the tracepoint - * specially here. - */ - trace_tlb_flush_rcuidle(TLB_FLUSH_ON_TASK_SWITCH, - TLB_FLUSH_ALL); + trace_tlb_flush(TLB_FLUSH_ON_TASK_SWITCH, + TLB_FLUSH_ALL); } /* @@ -167,13 +159,7 @@ void switch_mm_irqs_off(struct mm_struct *prev, struct mm_struct *next, this_cpu_write(cpu_tlbstate.loaded_mm, next); write_cr3(__pa(next->pgd)); - /* - * This gets called via leave_mm() in the idle path where RCU - * functions differently. Tracing normally uses RCU, so we - * have to call the tracepoint specially here. - */ - trace_tlb_flush_rcuidle(TLB_FLUSH_ON_TASK_SWITCH, - TLB_FLUSH_ALL); + trace_tlb_flush(TLB_FLUSH_ON_TASK_SWITCH, TLB_FLUSH_ALL); } load_mm_cr4(next); diff --git a/drivers/acpi/processor_idle.c b/drivers/acpi/processor_idle.c index 5c8aa9cf62d7..fe3d2a40f311 100644 --- a/drivers/acpi/processor_idle.c +++ b/drivers/acpi/processor_idle.c @@ -708,8 +708,6 @@ static DEFINE_RAW_SPINLOCK(c3_lock); static void acpi_idle_enter_bm(struct acpi_processor *pr, struct acpi_processor_cx *cx, bool timer_bc) { - acpi_unlazy_tlb(smp_processor_id()); - /* * Must be done before busmaster disable as we might need to * access HPET ! diff --git a/drivers/idle/intel_idle.c b/drivers/idle/intel_idle.c index 216d7ec88c0c..2ae43f59091d 100644 --- a/drivers/idle/intel_idle.c +++ b/drivers/idle/intel_idle.c @@ -912,16 +912,15 @@ static __cpuidle int intel_idle(struct cpuidle_device *dev, struct cpuidle_state *state = &drv->states[index]; unsigned long eax = flg2MWAIT(state->flags); unsigned int cstate; - int cpu = smp_processor_id(); cstate = (((eax) >> MWAIT_SUBSTATE_SIZE) & MWAIT_CSTATE_MASK) + 1; /* - * leave_mm() to avoid costly and often unnecessary wakeups - * for flushing the user TLB's associated with the active mm. + * NB: if CPUIDLE_FLAG_TLB_FLUSHED is set, this idle transition + * will probably flush the TLB. It's not guaranteed to flush + * the TLB, though, so it's not clear that we can do anything + * useful with this knowledge. */ - if (state->flags & CPUIDLE_FLAG_TLB_FLUSHED) - leave_mm(cpu); if (!(lapic_timer_reliable_states & (1 << (cstate)))) tick_broadcast_enter(); -- 2.20.1