[PULL,9/9] plugins: expand the bb plugin to be thread safe and track per-cpu

Commit Message

Alex Bennée July 14, 2020, 9:52 a.m. UTC

While there isn't any easy way to make the inline counts thread safe
we can ensure the callback based ones are. While we are at it we can
reduce introduce a new option ("idle") to dump a report of the current
bb and insn count each time a vCPU enters the idle state.

Signed-off-by: Alex Bennée <[e-mail]>
Reviewed-by: Robert Foley <[e-mail]>
Cc: Dave Bort <[e-mail]>

Message-Id: <[e-mail]>

Patch

diff --git a/tests/plugin/bb.c b/tests/plugin/bb.c
index df19fd359d..e4cc7fdd6e 100644
--- a/tests/plugin/bb.c
+++ b/tests/plugin/bb.c
@@ -16,24 +16,67 @@ 
 
 QEMU_PLUGIN_EXPORT int qemu_plugin_version = QEMU_PLUGIN_VERSION;
 
-static uint64_t bb_count;
-static uint64_t insn_count;
+typedef struct {
+    GMutex lock;
+    int index;
+    uint64_t bb_count;
+    uint64_t insn_count;
+} CPUCount;
+
+/* Used by the inline & linux-user counts */
 static bool do_inline;
+static CPUCount inline_count;
+
+/* Dump running CPU total on idle? */
+static bool idle_report;
+static GPtrArray *counts;
+static int max_cpus;
+
+static void gen_one_cpu_report(CPUCount *count, GString *report)
+{
+    if (count->bb_count) {
+        g_string_append_printf(report, "CPU%d: "
+                               "bb's: %" PRIu64", insns: %" PRIu64 "\n",
+                               count->index,
+                               count->bb_count, count->insn_count);
+    }
+}
 
 static void plugin_exit(qemu_plugin_id_t id, void *p)
 {
-    g_autofree gchar *out = g_strdup_printf(
-        "bb's: %" PRIu64", insns: %" PRIu64 "\n",
-        bb_count, insn_count);
-    qemu_plugin_outs(out);
+    g_autoptr(GString) report = g_string_new("");
+
+    if (do_inline || !max_cpus) {
+        g_string_printf(report, "bb's: %" PRIu64", insns: %" PRIu64 "\n",
+                        inline_count.bb_count, inline_count.insn_count);
+    } else {
+        g_ptr_array_foreach(counts, (GFunc) gen_one_cpu_report, report);
+    }
+    qemu_plugin_outs(report->str);
+}
+
+static void vcpu_idle(qemu_plugin_id_t id, unsigned int cpu_index)
+{
+    CPUCount *count = g_ptr_array_index(counts, cpu_index);
+    g_autoptr(GString) report = g_string_new("");
+    gen_one_cpu_report(count, report);
+
+    if (report->len > 0) {
+        g_string_prepend(report, "Idling ");
+        qemu_plugin_outs(report->str);
+    }
 }
 
 static void vcpu_tb_exec(unsigned int cpu_index, void *udata)
 {
-    unsigned long n_insns = (unsigned long)udata;
+    CPUCount *count = max_cpus ?
+        g_ptr_array_index(counts, cpu_index) : &inline_count;
 
-    insn_count += n_insns;
-    bb_count++;
+    unsigned long n_insns = (unsigned long)udata;
+    g_mutex_lock(&count->lock);
+    count->insn_count += n_insns;
+    count->bb_count++;
+    g_mutex_unlock(&count->lock);
 }
 
 static void vcpu_tb_trans(qemu_plugin_id_t id, struct qemu_plugin_tb *tb)
@@ -42,9 +85,10 @@  static void vcpu_tb_trans(qemu_plugin_id_t id, struct qemu_plugin_tb *tb)
 
     if (do_inline) {
         qemu_plugin_register_vcpu_tb_exec_inline(tb, QEMU_PLUGIN_INLINE_ADD_U64,
-                                                 &bb_count, 1);
+                                                 &inline_count.bb_count, 1);
         qemu_plugin_register_vcpu_tb_exec_inline(tb, QEMU_PLUGIN_INLINE_ADD_U64,
-                                                 &insn_count, n_insns);
+                                                 &inline_count.insn_count,
+                                                 n_insns);
     } else {
         qemu_plugin_register_vcpu_tb_exec_cb(tb, vcpu_tb_exec,
                                              QEMU_PLUGIN_CB_NO_REGS,
@@ -56,8 +100,35 @@  QEMU_PLUGIN_EXPORT int qemu_plugin_install(qemu_plugin_id_t id,
                                            const qemu_info_t *info,
                                            int argc, char **argv)
 {
-    if (argc && strcmp(argv[0], "inline") == 0) {
-        do_inline = true;
+    int i;
+
+    for (i = 0; i < argc; i++) {
+        char *opt = argv[i];
+        if (g_strcmp0(opt, "inline") == 0) {
+            do_inline = true;
+        } else if (g_strcmp0(opt, "idle") == 0) {
+            idle_report = true;
+        } else {
+            fprintf(stderr, "option parsing failed: %s\n", opt);
+            return -1;
+        }
+    }
+
+    if (info->system_emulation && !do_inline) {
+        max_cpus = info->system.max_vcpus;
+        counts = g_ptr_array_new();
+        for (i = 0; i < max_cpus; i++) {
+            CPUCount *count = g_new0(CPUCount, 1);
+            g_mutex_init(&count->lock);
+            count->index = i;
+            g_ptr_array_add(counts, count);
+        }
+    } else if (!do_inline) {
+        g_mutex_init(&inline_count.lock);
+    }
+
+    if (idle_report) {
+        qemu_plugin_register_vcpu_idle_cb(id, vcpu_idle);
     }
 
     qemu_plugin_register_vcpu_tb_trans_cb(id, vcpu_tb_trans);