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[PATCH v6 48/54] tests/plugin: add a hotblocks plugin
From: |
Alex Bennée |
Subject: |
[PATCH v6 48/54] tests/plugin: add a hotblocks plugin |
Date: |
Thu, 17 Oct 2019 14:16:09 +0100 |
This is a simple plugin to track which translation blocks are call
most often. As we don't have a view of the internals of TCG we can
only work by the address of the start of the block so we also need to
tracks how often the address is translated.
As there will be multiple blocks starting at the same address. We can
try and work around this by futzing the value to feed to the hash with
the insn count.
Signed-off-by: Alex Bennée <address@hidden>
Reviewed-by: Richard Henderson <address@hidden>
---
v5
- handle 0 length report
v6
- init api update
- use plugin_outs
squash! tests/plugin: add a hotblocks plugin
---
tests/plugin/Makefile | 1 +
tests/plugin/hotblocks.c | 143 +++++++++++++++++++++++++++++++++++++++
2 files changed, 144 insertions(+)
create mode 100644 tests/plugin/hotblocks.c
diff --git a/tests/plugin/Makefile b/tests/plugin/Makefile
index f9a3546ea3..e74940eaac 100644
--- a/tests/plugin/Makefile
+++ b/tests/plugin/Makefile
@@ -10,6 +10,7 @@ NAMES += bb
NAMES += empty
NAMES += insn
NAMES += mem
+NAMES += hotblocks
SONAMES := $(addsuffix .so,$(addprefix lib,$(NAMES)))
diff --git a/tests/plugin/hotblocks.c b/tests/plugin/hotblocks.c
new file mode 100644
index 0000000000..1bd183849a
--- /dev/null
+++ b/tests/plugin/hotblocks.c
@@ -0,0 +1,143 @@
+/*
+ * Copyright (C) 2019, Alex Bennée <address@hidden>
+ *
+ * License: GNU GPL, version 2 or later.
+ * See the COPYING file in the top-level directory.
+ */
+#include <inttypes.h>
+#include <assert.h>
+#include <stdlib.h>
+#include <inttypes.h>
+#include <string.h>
+#include <unistd.h>
+#include <stdio.h>
+#include <glib.h>
+
+#include <qemu-plugin.h>
+
+static bool do_inline;
+
+/* Plugins need to take care of their own locking */
+static GMutex lock;
+static GHashTable *hotblocks;
+static guint64 limit = 20;
+
+/*
+ * Counting Structure
+ *
+ * The internals of the TCG are not exposed to plugins so we can only
+ * get the starting PC for each block. We cheat this slightly by
+ * xor'ing the number of instructions to the hash to help
+ * differentiate.
+ */
+typedef struct {
+ uint64_t start_addr;
+ uint64_t exec_count;
+ int trans_count;
+ unsigned long insns;
+} ExecCount;
+
+static gint cmp_exec_count(gconstpointer a, gconstpointer b)
+{
+ ExecCount *ea = (ExecCount *) a;
+ ExecCount *eb = (ExecCount *) b;
+ return ea->exec_count > eb->exec_count ? -1 : 1;
+}
+
+static void plugin_exit(qemu_plugin_id_t id, void *p)
+{
+ g_autoptr(GString) report = g_string_new("collected ");
+ GList *counts, *it;
+ int i;
+
+ g_mutex_lock(&lock);
+ g_string_append_printf(report, "%d entries in the hash table\n",
+ g_hash_table_size(hotblocks));
+ counts = g_hash_table_get_values(hotblocks);
+ it = g_list_sort(counts, cmp_exec_count);
+
+ if (it) {
+ g_string_append_printf(report, "pc, tcount, icount, ecount\n");
+
+ for (i = 0; i < limit && it->next; i++, it = it->next) {
+ ExecCount *rec = (ExecCount *) it->data;
+ g_string_append_printf(report, "%#016"PRIx64", %d, %ld,
%"PRId64"\n",
+ rec->start_addr, rec->trans_count,
+ rec->insns, rec->exec_count);
+ }
+
+ g_list_free(it);
+ g_mutex_unlock(&lock);
+ }
+
+ qemu_plugin_outs(report->str);
+}
+
+static void plugin_init(void)
+{
+ hotblocks = g_hash_table_new(NULL, g_direct_equal);
+}
+
+static void vcpu_tb_exec(unsigned int cpu_index, void *udata)
+{
+ ExecCount *cnt;
+ uint64_t hash = (uint64_t) udata;
+
+ g_mutex_lock(&lock);
+ cnt = (ExecCount *) g_hash_table_lookup(hotblocks, (gconstpointer) hash);
+ /* should always succeed */
+ g_assert(cnt);
+ cnt->exec_count++;
+ g_mutex_unlock(&lock);
+}
+
+/*
+ * When do_inline we ask the plugin to increment the counter for us.
+ * Otherwise a helper is inserted which calls the vcpu_tb_exec
+ * callback.
+ */
+static void vcpu_tb_trans(qemu_plugin_id_t id, struct qemu_plugin_tb *tb)
+{
+ ExecCount *cnt;
+ uint64_t pc = qemu_plugin_tb_vaddr(tb);
+ unsigned long insns = qemu_plugin_tb_n_insns(tb);
+ uint64_t hash = pc ^ insns;
+
+ g_mutex_lock(&lock);
+ cnt = (ExecCount *) g_hash_table_lookup(hotblocks, (gconstpointer) hash);
+ if (cnt) {
+ cnt->trans_count++;
+ } else {
+ cnt = g_new0(ExecCount, 1);
+ cnt->start_addr = pc;
+ cnt->trans_count = 1;
+ cnt->insns = insns;
+ g_hash_table_insert(hotblocks, (gpointer) hash, (gpointer) cnt);
+ }
+
+ g_mutex_unlock(&lock);
+
+ if (do_inline) {
+ qemu_plugin_register_vcpu_tb_exec_inline(tb,
QEMU_PLUGIN_INLINE_ADD_U64,
+ &cnt->exec_count, 1);
+ } else {
+ qemu_plugin_register_vcpu_tb_exec_cb(tb, vcpu_tb_exec,
+ QEMU_PLUGIN_CB_NO_REGS,
+ (void *)hash);
+ }
+}
+
+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;
+ }
+
+ plugin_init();
+
+ qemu_plugin_register_vcpu_tb_trans_cb(id, vcpu_tb_trans);
+ qemu_plugin_register_atexit_cb(id, plugin_exit, NULL);
+ return 0;
+}
--
2.20.1
- [PATCH v6 39/54] plugin: add qemu_plugin_outs helper, (continued)
- [PATCH v6 39/54] plugin: add qemu_plugin_outs helper, Alex Bennée, 2019/10/17
- [PATCH v6 29/54] target/alpha: fetch code with translator_ld, Alex Bennée, 2019/10/17
- [PATCH v6 50/54] tests/plugin: add hotpages to analyse memory access patterns, Alex Bennée, 2019/10/17
- [PATCH v6 47/54] tests/tcg: enable plugin testing, Alex Bennée, 2019/10/17
- [PATCH v6 37/54] plugin: expand the plugin_init function to include an info block, Alex Bennée, 2019/10/17
- [PATCH v6 46/54] tests/tcg: drop test-i386-fprem from TESTS when not SLOW, Alex Bennée, 2019/10/17
- [PATCH v6 48/54] tests/plugin: add a hotblocks plugin,
Alex Bennée <=
- [PATCH v6 34/54] translator: inject instrumentation from plugins, Alex Bennée, 2019/10/17
- [PATCH v6 26/54] target/i386: fetch code with translator_ld, Alex Bennée, 2019/10/17
- [PATCH v6 15/54] tcg: let plugins instrument virtual memory accesses, Alex Bennée, 2019/10/17
- [PATCH v6 14/54] atomic_template: add inline trace/plugin helpers, Alex Bennée, 2019/10/17
- [PATCH v6 18/54] *-user: notify plugin of exit, Alex Bennée, 2019/10/17
- [PATCH v6 36/54] plugin: add API symbols to qemu-plugins.symbols, Alex Bennée, 2019/10/17
- [PATCH v6 25/54] target/sh4: fetch code with translator_ld, Alex Bennée, 2019/10/17
- [PATCH v6 33/54] target/openrisc: fetch code with translator_ld, Alex Bennée, 2019/10/17
- [PATCH v6 54/54] scripts/checkpatch.pl: don't complain about (foo, /* empty */), Alex Bennée, 2019/10/17