zhenwei pi <pizhen...@bytedance.com> writes:
> Originally we have to get all the vCPU registers and parse the
> specified one. To improve the performance of this usage, allow user
> specified vCPU id to query registers.
>
> Run a VM with 16 vCPU, use bcc tool to track the latency of
> 'hmp_info_registers':
> 'info registers -a' uses about 3ms;
> 'info registers 12' uses about 150us.
>
> Cc: Darren Kenny <darren.ke...@oracle.com>
> Signed-off-by: zhenwei pi <pizhen...@bytedance.com>
> ---
> hmp-commands-info.hx | 7 ++++---
> monitor/misc.c | 18 ++++++++++++++++++
> 2 files changed, 22 insertions(+), 3 deletions(-)
>
> diff --git a/hmp-commands-info.hx b/hmp-commands-info.hx
> index 3ffa24bd67..7a00b4ded3 100644
> --- a/hmp-commands-info.hx
> +++ b/hmp-commands-info.hx
> @@ -100,9 +100,10 @@ ERST
>
> {
> .name = "registers",
> - .args_type = "cpustate_all:-a",
> - .params = "[-a]",
> - .help = "show the cpu registers (-a: all - show register info
> for all cpus)",
> + .args_type = "cpustate_all:-a,vcpu:i?",
> + .params = "[-a|vcpu]",
> + .help = "show the cpu registers (-a: all - show register info
> for all cpus;"
> + " vcpu: specific vCPU to query)",
Recommend to document explicitly that it shows the current CPU's
registers when no argument is specified.
> .cmd = hmp_info_registers,
> },
>
> diff --git a/monitor/misc.c b/monitor/misc.c
> index 3d2312ba8d..8e1d4840f2 100644
> --- a/monitor/misc.c
> +++ b/monitor/misc.c
> @@ -307,6 +307,7 @@ int monitor_get_cpu_index(Monitor *mon)
> static void hmp_info_registers(Monitor *mon, const QDict *qdict)
> {
> bool all_cpus = qdict_get_try_bool(qdict, "cpustate_all", false);
> + int vcpu = qdict_get_try_int(qdict, "vcpu", -1);
> CPUState *cs;
>
> if (all_cpus) {
> @@ -314,6 +315,23 @@ static void hmp_info_registers(Monitor *mon, const QDict
> *qdict)
> monitor_printf(mon, "\nCPU#%d\n", cs->cpu_index);
> cpu_dump_state(cs, NULL, CPU_DUMP_FPU);
> }
> + } else if (vcpu >= 0) {
> + CPUState *target_cs = NULL;
> +
> + CPU_FOREACH(cs) {
> + if (cs->cpu_index == vcpu) {
> + target_cs = cs;
> + break;
> + }
> + }
Please use qemu_get_cpu().
> +
> + if (!target_cs) {
> + monitor_printf(mon, "CPU#%d not available\n", vcpu);
> + return;
> + }
> +
> + monitor_printf(mon, "\nCPU#%d\n", target_cs->cpu_index);
> + cpu_dump_state(target_cs, NULL, CPU_DUMP_FPU);
We show the CPU number when the user asked for this number, but ...
> } else {
> cs = mon_get_cpu(mon);
if (!cs) {
monitor_printf(mon, "No CPU available\n");
return;
}
cpu_dump_state(cs, NULL, CPU_DUMP_FPU);
... we don't show it when the user asked for the current CPU. It's
arguably more relevant then.
}
}
Suggest something like
} else {
cs = vcpu >= 0 ? qemu_get_cpu(vcpu) : mon_get_cpu(mon);
if (!cs) {
monitor_printf(mon, "CPU#%d not available\n", vcpu);
return;
}
monitor_printf(mon, "\nCPU#%d\n", cs->cpu_index);
cpu_dump_state(cs, NULL, CPU_DUMP_FPU);
}
