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trace: Allocate cpu->trace_dstate in place 

There's little point in dynamically allocating the bitmap if we
know at compile-time the max number of events we want to support.
Thus, make room in the struct for the bitmap, which will make things
easier later: this paves the way for upcoming changes, in which
we'll use a u32 to fully capture cpu->trace_dstate.

This change also increases performance by saving a dereference and
improving locality--note that this is important since upcoming work
makes reading this bitmap fairly common.

Signed-off-by: Emilio G. Cota <cota@braap.org>
Reviewed-by: Lluís Vilanova <vilanova@ac.upc.edu>
Signed-off-by: Lluís Vilanova <vilanova@ac.upc.edu>
Message-id: 149915725977.6295.15069969323605305641.stgit@frigg.lan
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
This commit is contained in:
Lluís Vilanova 2017-07-04 10:34:19 +02:00 committed by Stefan Hajnoczi
parent 4871b51b92
commit d01c05c955
3 changed files with 11 additions and 15 deletions
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9
include/qom/cpu.h
View File

@ -259,6 +259,7 @@ typedef void (*run_on_cpu_func)(CPUState *cpu, run_on_cpu_data data);
struct qemu_work_item;
#define CPU_UNSET_NUMA_NODE_ID -1
#define CPU_TRACE_DSTATE_MAX_EVENTS 32
/**
* CPUState:
@ -370,12 +371,8 @@ struct CPUState {
struct KVMState *kvm_state;
struct kvm_run *kvm_run;
/*
* Used for events with 'vcpu' and *without* the 'disabled' properties.
* Dynamically allocated based on bitmap requried to hold up to
* trace_get_vcpu_event_count() entries.
*/
unsigned long *trace_dstate;
/* Used for events with 'vcpu' and *without* the 'disabled' properties */
DECLARE_BITMAP(trace_dstate, CPU_TRACE_DSTATE_MAX_EVENTS);
/* TODO Move common fields from CPUArchState here. */
int cpu_index; /* used by alpha TCG */

8
qom/cpu.c
View File

@ -380,7 +380,6 @@ static void cpu_common_unrealizefn(DeviceState *dev, Error **errp)
static void cpu_common_initfn(Object *obj)
{
uint32_t count;
CPUState *cpu = CPU(obj);
CPUClass *cc = CPU_GET_CLASS(obj);
@ -395,18 +394,11 @@ static void cpu_common_initfn(Object *obj)
QTAILQ_INIT(&cpu->breakpoints);
QTAILQ_INIT(&cpu->watchpoints);
count = trace_get_vcpu_event_count();
if (count) {
cpu->trace_dstate = bitmap_new(count);
}
cpu_exec_initfn(cpu);
}
static void cpu_common_finalize(Object *obj)
{
CPUState *cpu = CPU(obj);
g_free(cpu->trace_dstate);
}
static int64_t cpu_common_get_arch_id(CPUState *cpu)

9
trace/control.c
View File

@ -65,8 +65,15 @@ void trace_event_register_group(TraceEvent **events)
size_t i;
for (i = 0; events[i] != NULL; i++) {
events[i]->id = next_id++;
if (events[i]->vcpu_id != TRACE_VCPU_EVENT_NONE) {
if (events[i]->vcpu_id == TRACE_VCPU_EVENT_NONE) {
continue;
}
if (likely(next_vcpu_id < CPU_TRACE_DSTATE_MAX_EVENTS)) {
events[i]->vcpu_id = next_vcpu_id++;
} else {
error_report("WARNING: too many vcpu trace events; dropping '%s'",
events[i]->name);
}
}
event_groups = g_renew(TraceEventGroup, event_groups, nevent_groups + 1);