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Commit 3f7f95c6 authored by Christian Ehrhardt's avatar Christian Ehrhardt Committed by Avi Kivity
Browse files

KVM: kvmtrace: replace get_cycles with ktime_get v3 



The current kvmtrace code uses get_cycles() while the interpretation would be
easier using using nanoseconds. ktime_get() should give at least the same
accuracy as get_cycles on all architectures (even better on 32bit archs) but
at a better unit (e.g. comparable between hosts with different frequencies.

[avi: avoid ktime_t in public header]

Signed-off-by: default avatarChristian Ehrhardt <ehrhardt@linux.vnet.ibm.com>
Acked-by: default avatarChristian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: default avatarAvi Kivity <avi@qumranet.com>
parent e32c8f2c

include/linux/kvm.h

+3 −3
Original line number Diff line number Diff line
@@ -322,12 +322,12 @@ struct kvm_trace_rec { 
	__u32 vcpu_id;

	union {

		struct {

			__u64 cycle_u64;

			__u64 timestamp;

			__u32 extra_u32[KVM_TRC_EXTRA_MAX];

		} __attribute__((packed)) cycle;

		} __attribute__((packed)) timestamp;

		struct {

			__u32 extra_u32[KVM_TRC_EXTRA_MAX];

		} nocycle;

		} notimestamp;

	} u;

};

virt/kvm/kvm_trace.c

+10 −9
Original line number Diff line number Diff line
@@ -17,6 +17,7 @@ 
#include <linux/module.h>

#include <linux/relay.h>

#include <linux/debugfs.h>

#include <linux/ktime.h>



#include <linux/kvm_host.h>
@@ -35,16 +36,16 @@ static struct kvm_trace *kvm_trace; 
struct kvm_trace_probe {

	const char *name;

	const char *format;

	u32 cycle_in;

	u32 timestamp_in;

	marker_probe_func *probe_func;

};



static inline int calc_rec_size(int cycle, int extra)

static inline int calc_rec_size(int timestamp, int extra)

{

	int rec_size = KVM_TRC_HEAD_SIZE;



	rec_size += extra;

	return cycle ? rec_size += KVM_TRC_CYCLE_SIZE : rec_size;

	return timestamp ? rec_size += KVM_TRC_CYCLE_SIZE : rec_size;

}



static void kvm_add_trace(void *probe_private, void *call_data,
@@ -69,20 +70,20 @@ static void kvm_add_trace(void *probe_private, void *call_data, 
	WARN_ON(!(extra <= KVM_TRC_EXTRA_MAX));

	extra 		= min_t(u32, extra, KVM_TRC_EXTRA_MAX);



	rec.rec_val |= TRACE_REC_TCS(p->cycle_in)

	rec.rec_val |= TRACE_REC_TCS(p->timestamp_in)

			| TRACE_REC_NUM_DATA_ARGS(extra);



	if (p->cycle_in) {

		rec.u.cycle.cycle_u64 = get_cycles();

	if (p->timestamp_in) {

		rec.u.timestamp.timestamp = ktime_to_ns(ktime_get());



		for (i = 0; i < extra; i++)

			rec.u.cycle.extra_u32[i] = va_arg(*args, u32);

			rec.u.timestamp.extra_u32[i] = va_arg(*args, u32);

	} else {

		for (i = 0; i < extra; i++)

			rec.u.nocycle.extra_u32[i] = va_arg(*args, u32);

			rec.u.notimestamp.extra_u32[i] = va_arg(*args, u32);

	}



	size = calc_rec_size(p->cycle_in, extra * sizeof(u32));

	size = calc_rec_size(p->timestamp_in, extra * sizeof(u32));

	relay_write(kt->rchan, &rec, size);

}