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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: Christian Ehrhardt <ehrhardt@linux.vnet.ibm.com>
Acked-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>
This commit is contained in:
Christian Ehrhardt 2008-07-14 14:00:01 +02:00 committed by Avi Kivity
parent e32c8f2c07
commit 3f7f95c65e
2 changed files with 13 additions and 12 deletions
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6
include/linux/kvm.h
View File

@ -322,12 +322,12 @@ struct kvm_trace_rec {
__u32 vcpu_id; __u32 vcpu_id;
union { union {
struct { struct {
__u64 cycle_u64; __u64 timestamp;
__u32 extra_u32[KVM_TRC_EXTRA_MAX]; __u32 extra_u32[KVM_TRC_EXTRA_MAX];
} __attribute__((packed)) cycle; } __attribute__((packed)) timestamp;
struct { struct {
__u32 extra_u32[KVM_TRC_EXTRA_MAX]; __u32 extra_u32[KVM_TRC_EXTRA_MAX];
} nocycle; } notimestamp;
} u; } u;
}; };

19
virt/kvm/kvm_trace.c
View File

@ -17,6 +17,7 @@
#include <linux/module.h> #include <linux/module.h>
#include <linux/relay.h> #include <linux/relay.h>
#include <linux/debugfs.h> #include <linux/debugfs.h>
#include <linux/ktime.h>
#include <linux/kvm_host.h> #include <linux/kvm_host.h>
@ -35,16 +36,16 @@ static struct kvm_trace *kvm_trace;
struct kvm_trace_probe { struct kvm_trace_probe {
const char *name; const char *name;
const char *format; const char *format;
u32 cycle_in; u32 timestamp_in;
marker_probe_func *probe_func; 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; int rec_size = KVM_TRC_HEAD_SIZE;
rec_size += extra; 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, 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)); WARN_ON(!(extra <= KVM_TRC_EXTRA_MAX));
extra = min_t(u32, 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); | TRACE_REC_NUM_DATA_ARGS(extra);
if (p->cycle_in) { if (p->timestamp_in) {
rec.u.cycle.cycle_u64 = get_cycles(); rec.u.timestamp.timestamp = ktime_to_ns(ktime_get());
for (i = 0; i < extra; i++) 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 { } else {
for (i = 0; i < extra; i++) 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); relay_write(kt->rchan, &rec, size);
} }