Emilio G Cota writes:
> 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 <c...@braap.org>
Reviewed-by: Lluís Vilanova <vilan...@ac.upc.edu>
> ---
> include/qom/cpu.h | 9 +++------
> qom/cpu.c | 8 --------
> trace/control.c | 9 ++++++++-
> 3 files changed, 11 insertions(+), 15 deletions(-)
> diff --git a/include/qom/cpu.h b/include/qom/cpu.h
> index 89ddb68..bc6e20f 100644
> --- a/include/qom/cpu.h
> +++ b/include/qom/cpu.h
> @@ -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:
> @@ -373,12 +374,8 @@ 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 */
> diff --git a/qom/cpu.c b/qom/cpu.c
> index 5069876..69fbb9c 100644
> --- a/qom/cpu.c
> +++ b/qom/cpu.c
> @@ -382,7 +382,6 @@ 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);
> @@ -397,18 +396,11 @@ 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)
> diff --git a/trace/control.c b/trace/control.c
> index 9b157b0..83740aa 100644
> --- a/trace/control.c
> +++ b/trace/control.c
> @@ -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);
> --
> 2.7.4
