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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: Andy Lutomirski <luto@kernel.org>
Reviewed-by: Nadav Amit <nadav.amit@gmail.com>
Reviewed-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Thomas 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: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Andy Lutomirski 2017-06-29 08:53:18 -07:00 committed by Ingo Molnar
parent 94b1b03b51
commit 43858b4f25
5 changed files with 7 additions and 28 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
arch/ia64/include/asm/acpi.h
View File

@ -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) \

2
arch/x86/include/asm/acpi.h
View File

@ -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)
{

20
arch/x86/mm/tlb.c
View File

@ -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);

2
drivers/acpi/processor_idle.c
View File

@ -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 !

9
drivers/idle/intel_idle.c
View File

@ -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();