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[RFC] plugins: expand the bb plugin to be thread safe and track per-cpu

Message ID 20200612200642.9714-1-alex.bennee@linaro.org
State New
Headers show
Series [RFC] plugins: expand the bb plugin to be thread safe and track per-cpu | expand

Commit Message

Alex Bennée June 12, 2020, 8:06 p.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 <alex.bennee@linaro.org>

Cc: Dave Bort <dbort@dbort.com>
---
 tests/plugin/bb.c | 85 ++++++++++++++++++++++++++++++++++++++++++-----
 1 file changed, 77 insertions(+), 8 deletions(-)

-- 
2.20.1
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Patch

diff --git a/tests/plugin/bb.c b/tests/plugin/bb.c
index df19fd359df..5c08367d3d7 100644
--- a/tests/plugin/bb.c
+++ b/tests/plugin/bb.c
@@ -16,24 +16,68 @@ 
 
 QEMU_PLUGIN_EXPORT int qemu_plugin_version = QEMU_PLUGIN_VERSION;
 
+/* Used by the inline counts */
 static uint64_t bb_count;
 static uint64_t insn_count;
 static bool do_inline;
 
+/* Dump running CPU total on idle? */
+static bool idle_report;
+
+typedef struct {
+    GMutex lock;
+    int index;
+    uint64_t bb_count;
+    uint64_t insn_count;
+} CPUCount;
+
+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) {
+        g_string_printf(report, "bb's: %" PRIu64", insns: %" PRIu64 "\n",
+                        bb_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)
 {
+    CPUCount *count = g_ptr_array_index(counts, cpu_index);
     unsigned long n_insns = (unsigned long)udata;
 
-    insn_count += n_insns;
-    bb_count++;
+    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)
@@ -56,8 +100,33 @@  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 (!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);
+        }
+    }
+
+    if (idle_report) {
+        qemu_plugin_register_vcpu_idle_cb(id, vcpu_idle);
     }
 
     qemu_plugin_register_vcpu_tb_trans_cb(id, vcpu_tb_trans);