[Qemu-devel] The details of round robin of multi-vcpu in TCG mode

[Qemu-devel] The details of round robin of multi-vcpu in TCG mode

[puckbee]

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Hi there:

Sorry to post this problem a second time, for I thought maybe the
question is not descripted clearly.

I'm studying the execution details of multi-vcpu in TCG mode.

The vcpus in TCG mode are executed one by one in a sequencial way,
according to some articles about Qemu.

I read the function [tcg_exec_all] in Qemu 1.3.0 as bellow, but the
implementation is not as expected.

[tcg_exec_all] will finally call [cpu_exec] to excute a loop to excute
the TBs in code cache

So,how does these functions control the running time of each VCPU?

That is,when will the execution of one VCPU return, in order to execute
the next_cpu in the loop of [tcg_exec_all].

Using alarm timer or other methonds?

        staticvoidtcg_exec_all(void)
        {
        intr;

        /* Account partial waits to the vm_clock. */
        qemu_clock_warp(vm_clock);

        if(next_cpu==NULL){
        next_cpu=first_cpu;
        }
        *for(;next_cpu!=NULL&&!exit_request;next_cpu=next_cpu->next_cpu){*
        CPUArchState*env=next_cpu;
        CPUState*cpu=ENV_GET_CPU(env);

        qemu_clock_enable(vm_clock,
        (env->singlestep_enabled&SSTEP_NOTIMER)==0);

        if(cpu_can_run(cpu)){
        ***r****=****tcg_cpu_exec**(**env**);*
        if(r==EXCP_DEBUG){
        cpu_handle_guest_debug(env);
        break;
        }
        }elseif(cpu->stop||cpu->stopped){
        break;
        }
        }
        exit_request=0;
        }

Yours
Puck

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Re: [Qemu-devel] The details of round robin of multi-vcpu in TCG mode

[li guang]

You can find the chance of exit main loop
by every calling of cpu_loop_exit() in cpu_exec().


在 2013-04-16二的 09:51 +0800，puckbee写道：
> Hi there:
> 
>     Sorry to post this problem a second time, for I thought maybe the
> question is not descripted clearly.
> 
>     I'm studying the execution details of multi-vcpu in TCG mode.
> 
>     The vcpus in TCG mode are executed one by one in a sequencial way,
> according to some articles about Qemu.
> 
>     I read the function [tcg_exec_all] in Qemu 1.3.0 as bellow, but
> the implementation is not as expected.
> 
>     [tcg_exec_all] will finally call [cpu_exec] to excute a loop to
> excute the TBs in code cache
> 
>     So,how does these functions control the running time of each VCPU?
>     
>     That is,when will the execution of one VCPU return, in order to
> execute the next_cpu in the loop of [tcg_exec_all].
> 
>     Using alarm timer or other methonds?
> 
>                 static void tcg_exec_all(void)
>                 {
>                     int r;
>                 
>                     /* Account partial waits to the vm_clock.  */
>                     qemu_clock_warp(vm_clock);
>                 
>                     if (next_cpu == NULL) {
>                         next_cpu = first_cpu;
>                     }
>                     for (; next_cpu != NULL && !
>                 exit_request; next_cpu = next_cpu->next_cpu) {
>                         CPUArchState *env = next_cpu;
>                         CPUState *cpu = ENV_GET_CPU(env);
>                 
>                         qemu_clock_enable(vm_clock,
>                                           (env->singlestep_enabled & SSTEP_NOTIMER) == 0);
>                 
>                         if (cpu_can_run(cpu)) {
>                             r = tcg_cpu_exec(env);
>                             if (r == EXCP_DEBUG) {
>                                 cpu_handle_guest_debug(env);
>                                 break;
>                             }
>                         } else if (cpu->stop || cpu->stopped) {
>                             break;
>                         }
>                     }
>                     exit_request = 0;
>                 }
>                 
> Yours
> Puck 

[Qemu-devel] Is Qemu now support x2apic in TCG mode?

[puckbee]

Hi there:

      Is there somebody can tell me that if qemu can support x2apic now?

      I've seen the x2apic in the definition of cpu flags, but can not 
find any implementation about x2apic.

      Thanks a lot if somebody can give me some hints~

puck
2013.4.18