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Commit 43858b4f authored by Andy Lutomirski's avatar Andy Lutomirski Committed by Ingo Molnar
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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: default avatarAndy Lutomirski <luto@kernel.org>
Reviewed-by: default avatarNadav Amit <nadav.amit@gmail.com>
Reviewed-by: default avatarBorislav Petkov <bp@suse.de>
Reviewed-by: default avatarThomas Gleixner <tglx@linutronix.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: linux-mm@kvack.org
Link: http://lkml.kernel.org/r/03c699cfd6021e467be650d6b73deaccfe4b4bd7.1498751203.git.luto@kernel.org


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent 94b1b03b

arch/ia64/include/asm/acpi.h

+0 −2
Original line number Diff line number Diff line
@@ -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)  \

arch/x86/include/asm/acpi.h

+0 −2
Original line number Diff line number Diff line
@@ -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)

{

arch/x86/mm/tlb.c

+3 −17
Original line number Diff line number Diff line
@@ -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)
@@ -117,14 +116,7 @@ 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,

			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);

drivers/acpi/processor_idle.c

+0 −2
Original line number Diff line number Diff line
@@ -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 !

drivers/idle/intel_idle.c

+4 −5
Original line number Diff line number Diff line
@@ -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();