[v8,10/11] monitor: adding new info cfg command

Adding "info cfg id depth" commands to HMP.
This command allow the exploration a TB
neighbors by dumping [and opening] a .dot
file with the TB CFG neighbors colorized
by their hotness.

The goal of this command is to allow the dynamic exploration
of TCG behavior and code quality. Therefore, for now, a
corresponding QMP command is not worthwhile.

Signed-off-by: Vanderson M. do Rosario <vandersonmr2@gmail.com>
---
 accel/tcg/tb-stats.c    | 164 ++++++++++++++++++++++++++++++++++++++++
 hmp-commands-info.hx    |   7 ++
 include/exec/tb-stats.h |   1 +
 monitor/misc.c          |  22 ++++++
 4 files changed, 194 insertions(+)

vandersonmr <vandersonmr2@gmail.com> writes:

> Adding "info cfg id depth" commands to HMP.
> This command allow the exploration a TB
> neighbors by dumping [and opening] a .dot
> file with the TB CFG neighbors colorized
> by their hotness.
>
> The goal of this command is to allow the dynamic exploration
> of TCG behavior and code quality. Therefore, for now, a
> corresponding QMP command is not worthwhile.
>
> Signed-off-by: Vanderson M. do Rosario <vandersonmr2@gmail.com>
> ---
>  accel/tcg/tb-stats.c    | 164 ++++++++++++++++++++++++++++++++++++++++
>  hmp-commands-info.hx    |   7 ++
>  include/exec/tb-stats.h |   1 +
>  monitor/misc.c          |  22 ++++++
>  4 files changed, 194 insertions(+)
>
> diff --git a/accel/tcg/tb-stats.c b/accel/tcg/tb-stats.c
> index d588c551c9..fd2344c5d1 100644
> --- a/accel/tcg/tb-stats.c
> +++ b/accel/tcg/tb-stats.c
> @@ -679,6 +679,170 @@ void dump_tb_info(int id, int log_mask, bool use_monitor)
>      /* tbdi free'd by do_dump_tb_info_safe */
>  }
>
> +/* TB CFG xdot/dot dump implementation */
> +#define MAX_CFG_NUM_NODES 1000
> +static int cfg_tb_id;
> +static GHashTable *cfg_nodes;
> +static uint64_t root_count;
> +
> +static void fputs_jump(TBStatistics *from, TBStatistics *to, FILE *dot)
> +{
> +    if (!from || !to) {
> +        return;
> +    }
> +
> +    int *from_id = (int *) g_hash_table_lookup(cfg_nodes, from);
> +    int *to_id   = (int *) g_hash_table_lookup(cfg_nodes, to);
> +
> +    if (!from_id || !to_id) {
> +        return;
> +    }
> +
> +    fprintf(dot, "   node_%d -> node_%d;\n", *from_id, *to_id);
> +}
> +
> +/* Hotness colors used in the CFG */
> +#define HOT_RED1  0xFF000 /* RGB(255,0,0)     */
> +#define HOT_RED2  0xFF333 /* RGB(255,51,48)   */
> +#define MILD_RED  0xFF666 /* RGB(255,102,96)  */
> +#define WEAK_RED1 0xFF999 /* RGB(255,153,144) */
> +#define WEAK_RED2 0xFFCCC /* RGB(255,204,192) */
> +
> +static void fputs_tbstats(TBStatistics *tbs, FILE *dot, int log_flags)
> +{
> +    if (!tbs) {
> +        return;
> +    }
> +
> +    uint32_t color = MILD_RED;
> +    uint64_t count = tbs->executions.normal;
> +    if (count > 1.6 * root_count) {
> +        color = HOT_RED1;
> +    } else if (count > 1.2 * root_count) {
> +        color = HOT_RED2;
> +    } else if (count < 0.4 * root_count) {
> +        color = WEAK_RED2;
> +    } else if (count < 0.8 * root_count) {
> +        color = WEAK_RED1;
> +    }
> +
> +    GString *code_s = get_code_string(tbs, log_flags);
> +
> +    for (int i = 0; i < code_s->len; i++) {
> +        if (code_s->str[i] == '\n') {
> +            code_s->str[i] = ' ';
> +            code_s = g_string_insert(code_s, i, "\\l");
> +            i += 2;
> +        }
> +    }
> +
> +    fprintf(dot,
> +            "   node_%d [fillcolor=\"#%xFF0000\" shape=\"record\" "
> +            "label=\"TB %d\\l"
> +            "-------------\\l"
> +            "PC:\t0x"TARGET_FMT_lx"\\l"
> +            "exec count:\t%lu\\l"
> +            "\\l %s\"];\n",
> +            cfg_tb_id, color, cfg_tb_id, tbs->pc,
> +            tbs->executions.normal, code_s->str);
> +
> +    int *id = g_new(int, 1);
> +    *id = cfg_tb_id;
> +    g_hash_table_insert(cfg_nodes, tbs, id);
> +
> +    cfg_tb_id++;
> +
> +    g_string_free(code_s, true);
> +}
> +
> +static void fputs_preorder_walk(TBStatistics *tbs, int depth, FILE *dot, int log_flags)
> +{
> +    if (tbs && depth > 0
> +            && cfg_tb_id < MAX_CFG_NUM_NODES
> +            && !g_hash_table_contains(cfg_nodes, tbs)) {
> +
> +        fputs_tbstats(tbs, dot, log_flags);
> +
> +        if (tbs->tb) {
> +            TranslationBlock *left_tb  = NULL;
> +            TranslationBlock *right_tb = NULL;
> +            if (tbs->tb->jmp_dest[0]) {
> +                left_tb = (TranslationBlock *) atomic_read(tbs->tb->jmp_dest);
> +            }
> +            if (tbs->tb->jmp_dest[1]) {
> +                right_tb = (TranslationBlock *) atomic_read(tbs->tb->jmp_dest + 1);
> +            }

I think my comments about relying on jmp_dest on the previous patch hold
for this as well.

> +
> +            if (left_tb) {
> +                fputs_preorder_walk(left_tb->tb_stats, depth - 1, dot, log_flags);
> +                fputs_jump(tbs, left_tb->tb_stats, dot);
> +            }
> +            if (right_tb) {
> +                fputs_preorder_walk(right_tb->tb_stats, depth - 1, dot, log_flags);
> +                fputs_jump(tbs, right_tb->tb_stats, dot);
> +            }
> +        }
> +    }
> +}
> +
> +struct PreorderInfo {
> +    TBStatistics *tbs;
> +    int depth;
> +    int log_flags;
> +};
> +
> +static void fputs_preorder_walk_safe(CPUState *cpu, run_on_cpu_data icmd)
> +{
> +    struct PreorderInfo *info = icmd.host_ptr;
> +
> +    GString *file_name = g_string_new(NULL);;
> +    g_string_printf(file_name, "/tmp/qemu-cfg-tb-%d-%d.dot", id,
> info->depth);

g_string is great for building things up on the fly but slight overkill
for this sort of case. Besides I think using g_file_open_tmp might be a
better choice than hand rolling our own magic tmp file code.

  int dot_fd = g_file_open_tmp("qemu-cfg-XXXX", &name, &error);

> +    FILE *dot = fopen(file_name->str, "w+");
> +
> +    fputs(
> +            "digraph G {\n"
> +            "   mclimit=1.5;\n"
> +            "   rankdir=TD; ordering=out;\n"
> +            "   graph[fontsize=10 fontname=\"Verdana\"];\n"
> +            "   color=\"#efefef\";\n"
> +            "   node[shape=box style=filled fontsize=8 fontname=\"Verdana\" fillcolor=\"#efefef\"];\n"
> +            "   edge[fontsize=8 fontname=\"Verdana\"];\n"
> +         , dot);
> +
> +    cfg_nodes = g_hash_table_new(NULL, NULL);
> +    fputs_preorder_walk(info->tbs, info->depth, dot, info->log_flags);
> +    g_hash_table_destroy(cfg_nodes);
> +
> +    fputs("}\n\0", dot);
> +    fclose(dot);
> +
> +    qemu_log("CFG dumped: %s\n", file_name->str);

  qemu_log("CFG dumped: %s\n", name);
  g_free(name);

> +
> +    g_string_free(file_name, true);
> +    g_free(info);
> +}
> +
> +void dump_tb_cfg(int id, int depth, int log_flags)
> +{
> +    cfg_tb_id = 1;
> +    root_count = 0;
> +
> +    /* do a pre-order walk in the CFG with a limited depth */
> +    TBStatistics *root = get_tbstats_by_id(id);
> +    if (root) {
> +        root_count = root->executions.normal;
> +    }
> +
> +    struct PreorderInfo *info = g_new(struct PreorderInfo, 1);
> +    info->tbs = root;
> +    info->depth = depth + 1;
> +    info->log_flags = log_flags;
> +    async_safe_run_on_cpu(first_cpu, fputs_preorder_walk_safe,
> +            RUN_ON_CPU_HOST_PTR(info));
> +}
> +
> +/* TBStatistic collection controls */
> +
>
>  void enable_collect_tb_stats(void)
>  {
> diff --git a/hmp-commands-info.hx b/hmp-commands-info.hx
> index f415479011..8c96924c0b 100644
> --- a/hmp-commands-info.hx
> +++ b/hmp-commands-info.hx
> @@ -305,6 +305,13 @@ ETEXI
>                        "dump flags can be used to set dump code level: out_asm in_asm op",
>          .cmd        = hmp_info_tb,
>      },
> +    {
> +        .name       = "cfg",
> +        .args_type  = "id:i,depth:i?,flags:s?",
> +        .params     = "id [depth flags]",
> +        .help       = "plot CFG around TB with the given id",
> +        .cmd        = hmp_info_cfg,
> +    },
>      {
>          .name       = "coverset",
>          .args_type  = "coverage:i?",
> diff --git a/include/exec/tb-stats.h b/include/exec/tb-stats.h
> index 51d73e1c5f..4515db106a 100644
> --- a/include/exec/tb-stats.h
> +++ b/include/exec/tb-stats.h
> @@ -155,6 +155,7 @@ void dump_tbs_info(int count, int sort_by, bool use_monitor);
>   */
>  void dump_tb_info(int id, int log_mask, bool use_monitor);
>
> +void dump_tb_cfg(int id, int depth, int log_flags);
>
>  /* TBStatistic collection controls */
>  void enable_collect_tb_stats(void);
> diff --git a/monitor/misc.c b/monitor/misc.c
> index b99c018124..b3b31d7035 100644
> --- a/monitor/misc.c
> +++ b/monitor/misc.c
> @@ -556,6 +556,28 @@ static void hmp_info_tb(Monitor *mon, const QDict *qdict)
>      dump_tb_info(id, mask, true);
>  }
>
> +static void hmp_info_cfg(Monitor *mon, const QDict *qdict)
> +{
> +    const int id = qdict_get_int(qdict, "id");
> +    const int depth = qdict_get_try_int(qdict, "depth", 3);
> +    const char *flags = qdict_get_try_str(qdict, "flags");
> +    int mask;
> +
> +    if (!tcg_enabled()) {
> +        error_report("TB information is only available with accel=tcg");
> +        return;
> +    }
> +
> +    mask = flags ? qemu_str_to_log_mask(flags) : CPU_LOG_TB_IN_ASM;
> +
> +    if (!mask) {
> +        error_report("Unable to parse log flags, see 'help log'");
> +        return;
> +    }
> +
> +    dump_tb_cfg(id, depth, mask);
> +}
> +
>  static void hmp_info_coverset(Monitor *mon, const QDict *qdict)
>  {
>      int coverage;


--
Alex Bennée