[Qemu-devel] [PATCH v4 6/7] monitor: adding tb_stats hmp command

[vandersonmr <vandersonmr2@gmail.com>]

Adding tb_stats [start|pause|stop|filter] command to hmp.
This allows controlling the collection of statistics.
It is also possible to set the level of collection:
all, jit, or exec.

The goal of this command is to allow the dynamic exploration
of the TCG behavior and 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    | 107 ++++++++++++++++++++++++++++++++++++++++
 hmp-commands.hx         |  17 +++++++
 include/exec/tb-stats.h |  13 +++++
 include/qemu/log.h      |   1 +
 monitor/misc.c          |  40 +++++++++++++++
 5 files changed, 178 insertions(+)

diff --git a/accel/tcg/tb-stats.c b/accel/tcg/tb-stats.c
index 44497d4f9b..6c330e1b02 100644
--- a/accel/tcg/tb-stats.c
+++ b/accel/tcg/tb-stats.c
@@ -6,6 +6,9 @@
 
 #include "qemu/qemu-print.h"
 
+/* only accessed in safe work */
+static GList *last_search;
+
 struct jit_profile_info {
     uint64_t translations;
     uint64_t aborted;
@@ -104,4 +107,108 @@ void dump_jit_profile_info(TCGProfile *s)
     }
 }
 
+static void dessaloc_tbstats(void *p, uint32_t hash, void *userp)
+{
+    g_free(p);
+}
+
+void clean_tbstats(void)
+{
+    /* remove all tb_stats */
+    qht_iter(&tb_ctx.tb_stats, dessaloc_tbstats, NULL);
+    qht_destroy(&tb_ctx.tb_stats);
+}
+
+static void reset_tbstats_flag(void *p, uint32_t hash, void *userp)
+{
+    uint32_t flag = *((int *)userp);
+    TBStatistics *tbs = p;
+    tbs->stats_enabled = flag;
+}
+
+void set_tbstats_flags(uint32_t flag)
+{
+    /* iterate over tbstats setting their flag as TB_NOTHING */
+    qht_iter(&tb_ctx.tb_stats, reset_tbstats_flag, &flag);
+}
+
+void do_hmp_tbstats_safe(CPUState *cpu, run_on_cpu_data icmd)
+{
+    struct TbstatsCommand *cmdinfo = icmd.host_ptr;
+    int cmd = cmdinfo->cmd;
+    uint32_t level = cmdinfo->level;
+
+    /* for safe, always pause TB generation while running this commands */
+    mmap_lock();
+
+    switch (cmd) {
+    case START:
+        if (tb_stats_collection_paused()) {
+            set_tbstats_flags(level);
+        } else {
+            if (tb_stats_collection_enabled()) {
+                qemu_printf("TB information already being recorded");
+                return;
+            }
+            qht_init(&tb_ctx.tb_stats, tb_stats_cmp, CODE_GEN_HTABLE_SIZE,
+                        QHT_MODE_AUTO_RESIZE);
+        }
+
+        set_default_tbstats_flag(level);
+        enable_collect_tb_stats();
+        tb_flush(cpu);
+        break;
+    case PAUSE:
+        if (!tb_stats_collection_enabled()) {
+            qemu_printf("TB information not being recorded");
+            return;
+        }
+
+        /* Continue to create TBStatistic structures but stop collecting statistics */
+        pause_collect_tb_stats();
+        tb_flush(cpu);
+        set_default_tbstats_flag(TB_NOTHING);
+        set_tbstats_flags(TB_PAUSED);
+        break;
+    case STOP:
+        if (!tb_stats_collection_enabled()) {
+            qemu_printf("TB information not being recorded");
+            return;
+        }
+
+        /* Dissalloc all TBStatistics structures and stop creating new ones */
+        disable_collect_tb_stats();
+        tb_flush(cpu);
+        clean_tbstats();
+        break;
+    case FILTER:
+        if (!tb_stats_collection_enabled()) {
+            qemu_printf("TB information not being recorded");
+            return;
+        }
+        if (!last_search) {
+            qemu_printf("no search on record! execute info tbs before filtering!");
+            return;
+        }
+
+        tb_flush(cpu);
+        set_default_tbstats_flag(TB_NOTHING);
+
+        /* Set all tbstats as paused, then return only the ones from last_search */
+        pause_collect_tb_stats();
+        set_tbstats_flags(TB_PAUSED);
+
+        for (GList *iter = last_search; iter; iter = g_list_next(iter)) {
+            TBStatistics *tbs = iter->data;
+            tbs->stats_enabled = level;
+        }
+
+        break;
+    default: /* INVALID */
+        break;
+    }
+
+    mmap_unlock();
+    g_free(cmdinfo);
+}
 
diff --git a/hmp-commands.hx b/hmp-commands.hx
index bfa5681dd2..419898751e 100644
--- a/hmp-commands.hx
+++ b/hmp-commands.hx
@@ -1885,6 +1885,23 @@ STEXI
 @findex qemu-io
 Executes a qemu-io command on the given block device.
 
+ETEXI
+#if defined(CONFIG_TCG)
+    {
+        .name       = "tb_stats",
+        .args_type  = "command:s,level:s?",
+        .params     = "command [stats_level]",
+        .help       = "Control tb statistics collection:"
+                        "tb_stats (start|pause|stop|filter) [all|jit_stats|exec_stats]",
+        .cmd        = hmp_tbstats,
+    },
+#endif
+
+STEXI
+@item tb_stats
+@findex
+Control recording tb statistics
+
 ETEXI
 
     {
diff --git a/include/exec/tb-stats.h b/include/exec/tb-stats.h
index 7d775f2c0d..d1debd3262 100644
--- a/include/exec/tb-stats.h
+++ b/include/exec/tb-stats.h
@@ -6,6 +6,9 @@
 #include "exec/tb-context.h"
 #include "tcg.h"
 
+enum SortBy { SORT_BY_HOTNESS, SORT_BY_HG /* Host/Guest */, SORT_BY_SPILLS };
+enum TbstatsCmd { START, PAUSE, STOP, FILTER };
+
 #define tb_stats_enabled(tb, JIT_STATS) \
     (tb && tb->tb_stats && (tb->tb_stats->stats_enabled & JIT_STATS))
 
@@ -60,4 +63,14 @@ bool tb_stats_cmp(const void *ap, const void *bp);
 
 void dump_jit_profile_info(TCGProfile *s);
 
+void set_tbstats_flags(uint32_t flags);
+void clean_tbstats(void);
+
+struct TbstatsCommand {
+    enum TbstatsCmd cmd;
+    uint32_t level;
+};
+
+void do_hmp_tbstats_safe(CPUState *cpu, run_on_cpu_data icmd);
+
 #endif
diff --git a/include/qemu/log.h b/include/qemu/log.h
index 93642603e5..47071d72c7 100644
--- a/include/qemu/log.h
+++ b/include/qemu/log.h
@@ -133,6 +133,7 @@ void qemu_log_close(void);
 #define TB_NOTHING    0
 #define TB_EXEC_STATS (1 << 1)
 #define TB_JIT_STATS  (1 << 2)
+#define TB_PAUSED     (1 << 3)
 
 void enable_collect_tb_stats(void);
 void disable_collect_tb_stats(void);
diff --git a/monitor/misc.c b/monitor/misc.c
index 00338c002a..aea9b0db4f 100644
--- a/monitor/misc.c
+++ b/monitor/misc.c
@@ -459,6 +459,46 @@ static void hmp_info_registers(Monitor *mon, const QDict *qdict)
 }
 
 #ifdef CONFIG_TCG
+static void hmp_tbstats(Monitor *mon, const QDict *qdict)
+{
+    if (!tcg_enabled()) {
+        error_report("TB information is only available with accel=tcg");
+        return;
+    }
+
+    char *cmd = (char *) qdict_get_try_str(qdict, "command");
+    enum TbstatsCmd icmd = -1;
+
+    if (strcmp(cmd, "start") == 0) {
+        icmd = START;
+    } else if (strcmp(cmd, "pause") == 0) {
+        icmd = PAUSE;
+    } else if (strcmp(cmd, "stop") == 0) {
+        icmd = STOP;
+    } else if (strcmp(cmd, "filter") == 0) {
+        icmd = FILTER;
+    } else {
+        error_report("invalid command!");
+    }
+
+    char *slevel = (char *) qdict_get_try_str(qdict, "level");
+    uint32_t level = TB_EXEC_STATS | TB_JIT_STATS;
+    if (slevel) {
+        if (strcmp(slevel, "jit_stats") == 0) {
+            level = TB_JIT_STATS;
+        } else if (strcmp(slevel, "exec_stats") == 0) {
+            level = TB_EXEC_STATS;
+        }
+    }
+
+    struct TbstatsCommand *tbscommand = g_new0(struct TbstatsCommand, 1);
+    tbscommand->cmd = icmd;
+    tbscommand->level = level;
+    async_safe_run_on_cpu(first_cpu, do_hmp_tbstats_safe,
+                          RUN_ON_CPU_HOST_PTR(tbscommand));
+
+}
+
 static void hmp_info_jit(Monitor *mon, const QDict *qdict)
 {
     if (!tcg_enabled()) {
-- 
2.22.0