Re: [Xen-devel] [PATCH v6 5/5] xen: add debugtrace entry when entry count is wrapping

[Jan Beulich <jbeulich@xxxxxxxx>]

On 09.09.2019 09:35, Juergen Gross wrote:
> @@ -173,10 +177,23 @@ void debugtrace_printk(const char *fmt, ...)
>      nr = vsnprintf(buf, sizeof(buf), fmt, args);
>      va_end(args);
>  
> +    if ( count == DEBUGTRACE_COUNT_WRAP )
> +    {
> +        count = 0;
> +        wrap_cnt++;
> +    }
> +
>      if ( debugtrace_send_to_console )
>      {
> -        unsigned int n = scnprintf(cntbuf, sizeof(cntbuf), "%u ", ++count);
> +        unsigned int n;
> +
> +        if ( count == 0 )
> +        {
> +            n = scnprintf(cntbuf, sizeof(cntbuf), "wrap: %lu\n", wrap_cnt);
> +            console_serial_puts(cntbuf, n);
> +        }
>  
> +        n = scnprintf(cntbuf, sizeof(cntbuf), "%u ", ++count);
>          console_serial_puts(cntbuf, n);
>          console_serial_puts(buf, nr);
>      }

Just one minor remark: In this case you issue a "wrap" message at
start of day, ...

> @@ -184,8 +201,16 @@ void debugtrace_printk(const char *fmt, ...)
>      {
>          unsigned int cpu = debugtrace_per_cpu ? smp_processor_id() : 0;
>  
> -        if ( debugtrace_buf_empty || strcmp(buf, last_buf) )
> +        if ( debugtrace_buf_empty || wrap_cnt != data->wrap_cnt ||
> +             strcmp(buf, last_buf) )
>          {
> +            if ( wrap_cnt != data->wrap_cnt )
> +            {
> +                snprintf(cntbuf, sizeof(cntbuf), "wrap: %lu->%lu\n",
> +                         data->wrap_cnt, wrap_cnt);
> +                debugtrace_add_to_buf(cntbuf);
> +                data->wrap_cnt = wrap_cnt;
> +            }
>              debugtrace_buf_empty = false;
>              last_prd = data->prd;
>              last_count = ++count;

... whereas here one gets issued (as I'd expect it) only after the
first wrapping of "count".

Jan

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