Commit d01c05c9 authored by Lluís Vilanova's avatar Lluís Vilanova Committed by Stefan Hajnoczi
Browse files

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: default avatarEmilio G. Cota <cota@braap.org>
Reviewed-by: default avatarLluís Vilanova <vilanova@ac.upc.edu>
Signed-off-by: default avatarLluís Vilanova <vilanova@ac.upc.edu>
Message-id: 149915725977.6295.15069969323605305641.stgit@frigg.lan
Signed-off-by: default avatarStefan Hajnoczi <stefanha@redhat.com>
parent 4871b51b

include/qom/cpu.h

+3 −6
Original line number Diff line number Diff line
@@ -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 */

qom/cpu.c

+0 −8
Original line number Diff line number Diff line
@@ -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)

trace/control.c

+8 −1
Original line number Diff line number Diff line
@@ -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);