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Commit e4074b30 authored by Vince Weaver's avatar Vince Weaver Committed by Ingo Molnar
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perf/x86: Enable overflow on Intel KNC with a custom knc_pmu_handle_irq() 



Although based on the Intel P6 design, the interrupt mechnanism
for KNC more closely resembles the Intel architectural
perfmon one.

We can't just re-use that code though, because KNC has different
MSR numbers for the status and ack registers.

In this case we just cut-and paste from perf_event_intel.c
with some minor changes, as it looks like it would not be
worth the trouble to change that code to be MSR-configurable.

Signed-off-by: default avatarVince Weaver <vincent.weaver@maine.edu>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
Cc: eranian@gmail.com
Cc: Meadows Lawrence F <lawrence.f.meadows@intel.com>
Link: http://lkml.kernel.org/r/alpine.DEB.2.02.1210171304410.23243@vincent-weaver-1.um.maine.edu


[ Small stylistic edits. ]
Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent 7d011962

arch/x86/kernel/cpu/perf_event_knc.c

+77 −1
Original line number Diff line number Diff line
@@ -3,6 +3,8 @@ 
#include <linux/perf_event.h>

#include <linux/types.h>



#include <asm/hardirq.h>



#include "perf_event.h"



static const u64 knc_perfmon_event_map[] =
@@ -193,6 +195,80 @@ static void knc_pmu_enable_event(struct perf_event *event) 
	(void)wrmsrl_safe(hwc->config_base + hwc->idx, val);

}



static inline u64 knc_pmu_get_status(void)

{

	u64 status;



	rdmsrl(MSR_KNC_IA32_PERF_GLOBAL_STATUS, status);



	return status;

}



static inline void knc_pmu_ack_status(u64 ack)

{

	wrmsrl(MSR_KNC_IA32_PERF_GLOBAL_OVF_CONTROL, ack);

}



static int knc_pmu_handle_irq(struct pt_regs *regs)

{

	struct perf_sample_data data;

	struct cpu_hw_events *cpuc;

	int handled = 0;

	int bit, loops;

	u64 status;



	cpuc = &__get_cpu_var(cpu_hw_events);



	knc_pmu_disable_all();



	status = knc_pmu_get_status();

	if (!status) {

		knc_pmu_enable_all(0);

		return handled;

	}



	loops = 0;

again:

	knc_pmu_ack_status(status);

	if (++loops > 100) {

		WARN_ONCE(1, "perf: irq loop stuck!\n");

		perf_event_print_debug();

		goto done;

	}



	inc_irq_stat(apic_perf_irqs);



	for_each_set_bit(bit, (unsigned long *)&status, X86_PMC_IDX_MAX) {

		struct perf_event *event = cpuc->events[bit];



		handled++;



		if (!test_bit(bit, cpuc->active_mask))

			continue;



		if (!intel_pmu_save_and_restart(event))

			continue;



		perf_sample_data_init(&data, 0, event->hw.last_period);



		if (perf_event_overflow(event, &data, regs))

			x86_pmu_stop(event, 0);

	}



	/*

	 * Repeat if there is more work to be done:

	 */

	status = knc_pmu_get_status();

	if (status)

		goto again;



done:

	knc_pmu_enable_all(0);



	return handled;

}





PMU_FORMAT_ATTR(event,	"config:0-7"	);

PMU_FORMAT_ATTR(umask,	"config:8-15"	);

PMU_FORMAT_ATTR(edge,	"config:18"	);
@@ -210,7 +286,7 @@ static struct attribute *intel_knc_formats_attr[] = { 


static __initconst struct x86_pmu knc_pmu = {

	.name			= "knc",

	.handle_irq		= x86_pmu_handle_irq,

	.handle_irq		= knc_pmu_handle_irq,

	.disable_all		= knc_pmu_disable_all,

	.enable_all		= knc_pmu_enable_all,

	.enable			= knc_pmu_enable_event,