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trace: remove global 'uint16 dstate[]' array 

Instead of having a global dstate array, declare a single
'uint16 TRACE_${EVENT_NAME}_DSTATE' variable for each
trace event. Record a pointer to this variable in the
TraceEvent struct too.

By turning trace_event_get_state_dynamic_by_id into a
macro, this still hits the fast path, and cache affinity
is ensured by declaring all the uint16 vars adjacent to
each other.

Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Lluís Vilanova <vilanova@ac.upc.edu>
Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
Message-id: 1475588159-30598-7-git-send-email-berrange@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
This commit is contained in:
Daniel P. Berrange 2016-10-04 14:35:45 +01:00 committed by Stefan Hajnoczi
parent 599ab2f241
commit 9397740244
8 changed files with 37 additions and 39 deletions
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3
scripts/tracetool/__init__.py
View File

@ -265,11 +265,12 @@ class Event(object):
QEMU_TRACE = "trace_%(name)s"
QEMU_TRACE_TCG = QEMU_TRACE + "_tcg"
QEMU_DSTATE = "_TRACE_%(NAME)s_DSTATE"
def api(self, fmt=None):
if fmt is None:
fmt = Event.QEMU_TRACE
return fmt % {"name": self.name}
return fmt % {"name": self.name, "NAME": self.name.upper()}
def transform(self, *trans):
"""Return a new Event with transformed Arguments."""

9
scripts/tracetool/format/events_c.py
View File

@ -25,6 +25,9 @@ def generate(events, backend):
'#include "trace/control.h"',
'')
for e in events:
out('uint16_t %s;' % e.api(e.QEMU_DSTATE))
out('TraceEvent trace_events[TRACE_EVENT_COUNT] = {')
for e in events:
@ -34,11 +37,13 @@ def generate(events, backend):
vcpu_id = "TRACE_VCPU_EVENT_COUNT"
out(' { .id = %(id)s, .vcpu_id = %(vcpu_id)s,'
' .name = \"%(name)s\",'
' .sstate = %(sstate)s },',
' .sstate = %(sstate)s,',
' .dstate = &%(dstate)s, }, ',
id = "TRACE_" + e.name.upper(),
vcpu_id = vcpu_id,
name = e.name,
sstate = "TRACE_%s_ENABLED" % e.name.upper())
sstate = "TRACE_%s_ENABLED" % e.name.upper(),
dstate = e.api(e.QEMU_DSTATE))
out('};',
'')

3
scripts/tracetool/format/events_h.py
View File

@ -32,6 +32,9 @@ def generate(events, backend):
out(' TRACE_EVENT_COUNT',
'} TraceEventID;')
for e in events:
out('extern uint16_t %s;' % e.api(e.QEMU_DSTATE))
# per-vCPU event identifiers
out('typedef enum {')

9
stubs/trace-control.c
View File

@ -18,22 +18,21 @@ void trace_event_set_state_dynamic_init(TraceEvent *ev, bool state)
void trace_event_set_state_dynamic(TraceEvent *ev, bool state)
{
TraceEventID id;
bool state_pre;
assert(trace_event_get_state_static(ev));
id = trace_event_get_id(ev);
/*
* We ignore the "vcpu" property here, since there's no target code. Then
* dstate can only be 1 or 0.
*/
state_pre = trace_events_dstate[id];
state_pre = *(ev->dstate);
if (state_pre != state) {
if (state) {
trace_events_enabled_count++;
trace_events_dstate[id] = 1;
*(ev->dstate) = 1;
} else {
trace_events_enabled_count--;
trace_events_dstate[id] = 0;
*(ev->dstate) = 0;
}
}
}

14
trace/control-internal.h
View File

@ -16,7 +16,6 @@
extern TraceEvent trace_events[];
extern uint16_t trace_events_dstate[];
extern int trace_events_enabled_count;
@ -54,18 +53,13 @@ static inline bool trace_event_get_state_static(TraceEvent *ev)
return ev->sstate;
}
static inline bool trace_event_get_state_dynamic_by_id(TraceEventID id)
{
/* it's on fast path, avoid consistency checks (asserts) */
return unlikely(trace_events_enabled_count) && trace_events_dstate[id];
}
/* it's on fast path, avoid consistency checks (asserts) */
#define trace_event_get_state_dynamic_by_id(id) \
(unlikely(trace_events_enabled_count) && _ ## id ## _DSTATE)
static inline bool trace_event_get_state_dynamic(TraceEvent *ev)
{
TraceEventID id;
assert(trace_event_get_state_static(ev));
id = trace_event_get_id(ev);
return trace_event_get_state_dynamic_by_id(id);
return unlikely(trace_events_enabled_count) && *ev->dstate;
}
static inline bool trace_event_get_vcpu_state_dynamic_by_vcpu_id(CPUState *vcpu,

25
trace/control-target.c
View File

@ -16,21 +16,20 @@
void trace_event_set_state_dynamic_init(TraceEvent *ev, bool state)
{
TraceEventID id = trace_event_get_id(ev);
bool state_pre;
assert(trace_event_get_state_static(ev));
/*
* We ignore the "vcpu" property here, since no vCPUs have been created
* yet. Then dstate can only be 1 or 0.
*/
state_pre = trace_events_dstate[id];
state_pre = *ev->dstate;
if (state_pre != state) {
if (state) {
trace_events_enabled_count++;
trace_events_dstate[id] = 1;
*ev->dstate = 1;
} else {
trace_events_enabled_count--;
trace_events_dstate[id] = 0;
*ev->dstate = 0;
}
}
}
@ -45,15 +44,14 @@ void trace_event_set_state_dynamic(TraceEvent *ev, bool state)
}
} else {
/* Without the "vcpu" property, dstate can only be 1 or 0 */
TraceEventID id = trace_event_get_id(ev);
bool state_pre = trace_events_dstate[id];
bool state_pre = *ev->dstate;
if (state_pre != state) {
if (state) {
trace_events_enabled_count++;
trace_events_dstate[id] = 1;
*ev->dstate = 1;
} else {
trace_events_enabled_count--;
trace_events_dstate[id] = 0;
*ev->dstate = 0;
}
}
}
@ -62,23 +60,21 @@ void trace_event_set_state_dynamic(TraceEvent *ev, bool state)
void trace_event_set_vcpu_state_dynamic(CPUState *vcpu,
TraceEvent *ev, bool state)
{
TraceEventID id;
TraceEventVCPUID vcpu_id;
bool state_pre;
assert(trace_event_get_state_static(ev));
assert(trace_event_is_vcpu(ev));
id = trace_event_get_id(ev);
vcpu_id = trace_event_get_vcpu_id(ev);
state_pre = test_bit(vcpu_id, vcpu->trace_dstate);
if (state_pre != state) {
if (state) {
trace_events_enabled_count++;
set_bit(vcpu_id, vcpu->trace_dstate);
trace_events_dstate[id]++;
(*ev->dstate)++;
} else {
trace_events_enabled_count--;
clear_bit(vcpu_id, vcpu->trace_dstate);
trace_events_dstate[id]--;
(*ev->dstate)--;
}
}
}
@ -105,12 +101,11 @@ void trace_init_vcpu(CPUState *vcpu)
if (trace_event_is_vcpu(ev) &&
trace_event_get_state_static(ev) &&
trace_event_get_state_dynamic(ev)) {
TraceEventID id = trace_event_get_id(ev);
if (adding_first_cpu()) {
/* check preconditions */
assert(trace_events_dstate[id] == 1);
assert(*ev->dstate == 1);
/* disable early-init state ... */
trace_events_dstate[id] = 0;
*ev->dstate = 0;
trace_events_enabled_count--;
/* ... and properly re-enable */
trace_event_set_vcpu_state_dynamic(vcpu, ev, true);

6
trace/control.c
View File

@ -28,12 +28,6 @@
#include "monitor/monitor.h"
int trace_events_enabled_count;
/*
* Interpretation depends on wether the event has the 'vcpu' property:
* - false: Boolean value indicating whether the event is active.
* - true : Integral counting the number of vCPUs that have this event enabled.
*/
uint16_t trace_events_dstate[TRACE_EVENT_COUNT];
QemuOptsList qemu_trace_opts = {
.name = "trace",

7
trace/event-internal.h
View File

@ -19,6 +19,12 @@
* @vcpu_id: Unique per-vCPU event identifier.
* @name: Event name.
* @sstate: Static tracing state.
* @dstate: Dynamic tracing state
*
* Interpretation of @dstate depends on whether the event has the 'vcpu'
* property:
* - false: Boolean value indicating whether the event is active.
* - true : Integral counting the number of vCPUs that have this event enabled.
*
* Opaque generic description of a tracing event.
*/
@ -27,6 +33,7 @@ typedef struct TraceEvent {
TraceEventVCPUID vcpu_id;
const char * name;
const bool sstate;
uint16_t *dstate;
} TraceEvent;
void trace_event_set_state_dynamic_init(TraceEvent *ev, bool state);