Emilio G. Cota <c...@braap.org> writes:
> Since commit 6e3b2bfd6 ("tcg: allocate TB structs before the
> corresponding translated code") we are not fully utilizing
> code_gen_buffer for translated code, and therefore are
> incorrectly reporting the amount of translated code as well as
> the average host TB size. Address this by:
>
> - Making the conscious choice of misreporting the total translated code;
> doing otherwise would mislead users into thinking "-tb-size" is not
> honoured.
>
> - Expanding tb_tree_stats to accurately count the bytes of translated code on
> the host, and using this for reporting the average tb host size,
> as well as the expansion ratio.
>
> In the future we might want to consider reporting the accurate numbers for
> the total translated code, together with a "bookkeeping/overhead" field to
> account for the TB structs.
>
> Signed-off-by: Emilio G. Cota <c...@braap.org>
> ---
> accel/tcg/translate-all.c | 34 ++++++++++++++++++++++++----------
> 1 file changed, 24 insertions(+), 10 deletions(-)
>
> diff --git a/accel/tcg/translate-all.c b/accel/tcg/translate-all.c
> index aa3a08b..aa71292 100644
> --- a/accel/tcg/translate-all.c
> +++ b/accel/tcg/translate-all.c
> @@ -898,9 +898,20 @@ static void page_flush_tb(void)
> }
> }
>
> +static __attribute__((unused))
> +gboolean tb_host_size_iter(gpointer key, gpointer value, gpointer data)
> +{
> + const TranslationBlock *tb = value;
> + size_t *size = data;
> +
> + *size += tb->tc_size;
> + return false;
> +}
> +
I think having the __attribute__ stuff is confusing. Why don't we just
do what the newer debug stuff does:
modified accel/tcg/translate-all.c
@@ -66,6 +66,12 @@
/* make various TB consistency checks */
/* #define DEBUG_TB_CHECK */
+#if defined(DEBUG_TB_FLUSH)
+#define DEBUG_TB_FLUSH_GATE 1
+#else
+#define DEBUG_TB_FLUSH_GATE 0
+#endif
+
#if !defined(CONFIG_USER_ONLY)
/* TB consistency checks only implemented for usermode emulation. */
#undef DEBUG_TB_CHECK
@@ -948,8 +954,7 @@ static void page_flush_tb(void)
}
}
-static __attribute__((unused))
-gboolean tb_host_size_iter(gpointer key, gpointer value, gpointer data)
+static gboolean tb_host_size_iter(gpointer key, gpointer value, gpointer data)
{
const TranslationBlock *tb = value;
size_t *size = data;
@@ -958,11 +963,22 @@ gboolean tb_host_size_iter(gpointer key, gpointer value,
gpointer data)
return false;
}
+static void dump_tb_sizes(void)
+{
+ if (DEBUG_TB_FLUSH_GATE) {
+ size_t host_size = 0;
+ int nb_tbs;
+
+ g_tree_foreach(tb_ctx.tb_tree, tb_host_size_iter, &host_size);
+ nb_tbs = g_tree_nnodes(tb_ctx.tb_tree);
+ fprintf(stderr, "qemu: flush code_size=%zu nb_tbs=%d
avg_tb_size=%zu\n",
+ tcg_code_size(), nb_tbs, nb_tbs > 0 ? host_size / nb_tbs : 0);
+ }
+}
+
/* flush all the translation blocks */
static void do_tb_flush(CPUState *cpu, run_on_cpu_data tb_flush_count)
{
- size_t host_size __attribute__((unused)) = 0;
- int nb_tbs __attribute__((unused));
tb_lock();
@@ -973,12 +989,7 @@ static void do_tb_flush(CPUState *cpu, run_on_cpu_data
tb_flush_count)
goto done;
}
-#if defined(DEBUG_TB_FLUSH)
- g_tree_foreach(tb_ctx.tb_tree, tb_host_size_iter, &host_size);
- nb_tbs = g_tree_nnodes(tb_ctx.tb_tree);
- fprintf(stderr, "qemu: flush code_size=%zu nb_tbs=%d avg_tb_size=%zu\n",
- tcg_code_size(), nb_tbs, nb_tbs > 0 ? host_size / nb_tbs : 0);
-#endif
+ dump_tb_sizes();
Which will a) ensure all the debug code is compiled even when not
enabled and b) the compiler won't bitch at you when it optimises stuff
away.
Better?
--
Alex Bennée
