Re: [Xen-devel] [PATCH] reduce useless output from 'd' console command

[Keir Fraser <keir.fraser@xxxxxxxxxxxxx>]

I quite like it as it is. The output for a CPU in guest mode is quite short,
and outputting printk("CPU%d blah") before doing the IPI also lets us see
very clearly if a CPU is probably not responding to IPI. I think changing
console_start_log_everything() to console_start_sync() would be a good idea,
at least for key 'd'.

 -- Keir

On 12/6/08 16:02, "Jan Beulich" <jbeulich@xxxxxxxxxx> wrote:

> Instead of printing context of the interrupt/IPI that invoked the
> output function, print just the interrupted context, and avoid
> printing the same context twice if the interrupted context was in guest
> space. This not only makes analyzing the output easier, it also helps
> reduce the amount of output in some cases, which is pretty significant
> given how easily the ring buffer overruns. (IA64 part only compile
> tested.)
> 
> Signed-off-by: Jan Beulich <jbeulich@xxxxxxxxxx>
> 
> Index: 2008-06-12/xen/arch/ia64/linux-xen/smp.c
> ===================================================================
> --- 2008-06-12.orig/xen/arch/ia64/linux-xen/smp.c 2008-06-12
> 16:46:04.000000000 +0200
> +++ 2008-06-12/xen/arch/ia64/linux-xen/smp.c 2008-06-11 08:37:37.000000000
> +0200
> @@ -175,7 +175,7 @@ handle_IPI (int irq, void *dev_id, struc
>       * At this point the structure may be gone unless
>       * wait is true.
>       */
> -          (*func)(info);
> +          (*func)(info ?: regs);
>  
>      /* Notify the sending CPU that the task is done.  */
>      mb();
> Index: 2008-06-12/xen/arch/x86/smp.c
> ===================================================================
> --- 2008-06-12.orig/xen/arch/x86/smp.c 2008-06-12 16:46:04.000000000 +0200
> +++ 2008-06-12/xen/arch/x86/smp.c 2008-06-11 08:35:19.000000000 +0200
> @@ -357,7 +357,7 @@ fastcall void smp_call_function_interrup
>  
>      if ( call_data->wait )
>      {
> -        (*func)(info);
> +        (*func)(info ?: regs);
>          mb();
>          atomic_inc(&call_data->finished);
>      }
> @@ -365,7 +365,7 @@ fastcall void smp_call_function_interrup
>      {
>          mb();
>          atomic_inc(&call_data->started);
> -        (*func)(info);
> +        (*func)(info ?: regs);
>      }
>  
>      irq_exit();
> Index: 2008-06-12/xen/common/keyhandler.c
> ===================================================================
> --- 2008-06-12.orig/xen/common/keyhandler.c 2008-06-12 16:46:04.000000000
> +0200
> +++ 2008-06-12/xen/common/keyhandler.c 2008-06-12 16:46:54.000000000 +0200
> @@ -91,14 +91,25 @@ static void show_handlers(unsigned char
>                     key_table[i].desc);
>  }
>  
> -static void __dump_execstate(void *unused)
> +static void __dump_execstate(void *_regs)
>  {
> -    dump_execution_state();
> -    printk("*** Dumping CPU%d guest state: ***\n", smp_processor_id());
> +    struct cpu_user_regs *regs = _regs;
> +    unsigned int cpu = smp_processor_id();
> +
> +    if ( !guest_mode(regs) )
> +    {
> +        printk("\n*** Dumping CPU%u host state: ***\n", cpu);
> +        show_execution_state(regs);
> +    }
>      if ( is_idle_vcpu(current) )
> -        printk("No guest context (CPU is idle).\n");
> +        printk("No guest context (CPU%u is idle).\n", cpu);
>      else
> +    {
> +        printk("*** Dumping CPU%u guest state (d%d:v%d): ***\n",
> +               smp_processor_id(), current->domain->domain_id,
> +               current->vcpu_id);
>          show_execution_state(guest_cpu_user_regs());
> +    }
>  }
>  
>  static void dump_registers(unsigned char key, struct cpu_user_regs *regs)
> @@ -108,14 +119,12 @@ static void dump_registers(unsigned char
>      printk("'%c' pressed -> dumping registers\n", key);
>  
>      /* Get local execution state out immediately, in case we get stuck. */
> -    printk("\n*** Dumping CPU%d host state: ***\n", smp_processor_id());
> -    __dump_execstate(NULL);
> +    __dump_execstate(regs);
>  
>      for_each_online_cpu ( cpu )
>      {
>          if ( cpu == smp_processor_id() )
>              continue;
> -        printk("\n*** Dumping CPU%d host state: ***\n", cpu);
>          on_selected_cpus(cpumask_of_cpu(cpu), __dump_execstate, NULL, 1, 1);
>      }
>  
> Index: 2008-06-12/xen/include/asm-ia64/linux-xen/asm/ptrace.h
> ===================================================================
> --- 2008-06-12.orig/xen/include/asm-ia64/linux-xen/asm/ptrace.h 2008-06-12
> 16:46:04.000000000 +0200
> +++ 2008-06-12/xen/include/asm-ia64/linux-xen/asm/ptrace.h 2008-06-11
> 08:57:07.000000000 +0200
> @@ -278,7 +278,7 @@ struct switch_stack {
>  # define ia64_task_regs(t)  (((struct pt_regs *) ((char *) (t) +
> IA64_STK_OFFSET)) - 1)
>  # define ia64_psr(regs)   ((struct ia64_psr *) &(regs)->cr_ipsr)
>  #ifdef XEN
> -# define guest_mode(regs)  (ia64_psr(regs)->cpl != 0)
> +# define guest_mode(regs)  (ia64_psr(regs)->cpl && !ia64_psr(regs)->vm)
>  # define guest_kernel_mode(regs) (ia64_psr(regs)->cpl == CONFIG_CPL0_EMUL)
>  # define vmx_guest_kernel_mode(regs) (ia64_psr(regs)->cpl == 0)
>  # define regs_increment_iip(regs)     \
> 
> 
> 
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> http://lists.xensource.com/xen-devel



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