Re: [PATCH v9 12/13] tb-stats: adding TBStatistics info into perf dump

[Richard Henderson]

On 10/7/19 11:28 AM, Alex Bennée wrote:
> diff --git a/accel/tcg/perf/jitdump.c b/accel/tcg/perf/jitdump.c
> index e1d6f2214e..e7b86173e0 100644
> --- a/accel/tcg/perf/jitdump.c
> +++ b/accel/tcg/perf/jitdump.c
> @@ -146,7 +146,20 @@ void start_jitdump_file(void)
>  
>  void append_load_in_jitdump_file(TranslationBlock *tb)
>  {
> -    gchar *func_name = g_strdup_printf("TB virt:0x"TARGET_FMT_lx, tb->pc);
> +    g_autoptr(GString) func_name = g_string_new("TB virt:");
> +
> +    g_string_append_printf(func_name, "0x"TARGET_FMT_lx, tb->pc);

I think it was clearer as a single printf.  Use g_string_printf().

But now I see where the missing GString went -- bad patch splitting.  ;-)

> +    if (tb->tb_stats) {
> +        TBStatistics *tbs = tb->tb_stats;
> +        unsigned g = stat_per_translation(tbs, code.num_guest_inst);
> +        unsigned ops = stat_per_translation(tbs, code.num_tcg_ops);
> +        unsigned ops_opt = stat_per_translation(tbs, code.num_tcg_ops_opt);
> +        unsigned spills = stat_per_translation(tbs, code.spills);
> +
> +        g_string_append_printf(func_name, " (g:%u op:%u opt:%u spills:%d)",
> +                               g, ops, ops_opt, spills);
> +    }

Oh, hum.  Does it really make sense to have accumulated averages here?  Why
does it not make more sense to have the statistics about this particular TB?
After all, different TB -- even for the same guest code -- will appear at
different places within the code_gen_buffer, and so have different entries in
this log.


r~