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Commit c323d95f authored by Yong Wang's avatar Yong Wang Committed by Ingo Molnar
Browse files

perf_counter/x86: Always use NMI for performance-monitoring interrupt 



Always use NMI for performance-monitoring interrupt as there could be
racy situations if we switch between irq and nmi mode frequently.

Signed-off-by: default avatarYong Wang <yong.y.wang@intel.com>
LKML-Reference: <20090529052835.GA13657@ywang-moblin2.bj.intel.com>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent da417a75

arch/x86/include/asm/perf_counter.h

+2 −2
Original line number Diff line number Diff line
@@ -91,10 +91,10 @@ extern void set_perf_counter_pending(void); 


#ifdef CONFIG_PERF_COUNTERS

extern void init_hw_perf_counters(void);

extern void perf_counters_lapic_init(int nmi);

extern void perf_counters_lapic_init(void);

#else

static inline void init_hw_perf_counters(void)		{ }

static inline void perf_counters_lapic_init(int nmi)	{ }

static inline void perf_counters_lapic_init(void)	{ }

#endif



#endif /* _ASM_X86_PERF_COUNTER_H */

arch/x86/kernel/apic/apic.c

+1 −1
Original line number Diff line number Diff line
@@ -1135,7 +1135,7 @@ void __cpuinit setup_local_APIC(void) 
		apic_write(APIC_ESR, 0);

	}

#endif

	perf_counters_lapic_init(0);

	perf_counters_lapic_init();



	preempt_disable();

arch/x86/kernel/cpu/perf_counter.c

+5 −14
Original line number Diff line number Diff line
@@ -604,7 +604,7 @@ static int x86_pmu_enable(struct perf_counter *counter) 
		hwc->counter_base = x86_pmu.perfctr;

	}



	perf_counters_lapic_init(hwc->nmi);

	perf_counters_lapic_init();



	x86_pmu.disable(hwc, idx);
@@ -863,24 +863,15 @@ void set_perf_counter_pending(void) 
	apic->send_IPI_self(LOCAL_PENDING_VECTOR);

}



void perf_counters_lapic_init(int nmi)

void perf_counters_lapic_init(void)

{

	u32 apic_val;



	if (!x86_pmu_initialized())

		return;



	/*

	 * Enable the performance counter vector in the APIC LVT:

	 * Always use NMI for PMU

	 */

	apic_val = apic_read(APIC_LVTERR);



	apic_write(APIC_LVTERR, apic_val | APIC_LVT_MASKED);

	if (nmi)

	apic_write(APIC_LVTPC, APIC_DM_NMI);

	else

		apic_write(APIC_LVTPC, LOCAL_PERF_VECTOR);

	apic_write(APIC_LVTERR, apic_val);

}



static int __kprobes
@@ -1054,7 +1045,7 @@ void __init init_hw_perf_counters(void) 


	pr_info("... counter mask:    %016Lx\n", perf_counter_mask);



	perf_counters_lapic_init(0);

	perf_counters_lapic_init();

	register_die_notifier(&perf_counter_nmi_notifier);

}