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[PULL v2 65/73] tests/plugin: add a hotblocks plugin
From: |
Alex Bennée |
Subject: |
[PULL v2 65/73] tests/plugin: add a hotblocks plugin |
Date: |
Fri, 25 Oct 2019 07:37:05 +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>
diff --git a/tests/plugin/Makefile b/tests/plugin/Makefile
index f9a3546ea32..e74940eaac5 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 00000000000..1bd183849a1
--- /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
- [PULL v2 07/73] travis.yml: bump Xcode 10 to latest dot release, (continued)
- [PULL v2 07/73] travis.yml: bump Xcode 10 to latest dot release, Alex Bennée, 2019/10/25
- [PULL v2 11/73] tests/vm/netbsd: Disable IPv6, Alex Bennée, 2019/10/25
- [PULL v2 13/73] gitlab-ci.yml: Use libvdeplug-dev to compile-test the VDE network backend, Alex Bennée, 2019/10/25
- [PULL v2 19/73] cpu: introduce cpu_in_exclusive_context(), Alex Bennée, 2019/10/25
- [PULL v2 56/73] plugin: add qemu_plugin_outs helper, Alex Bennée, 2019/10/25
- [PULL v2 72/73] MAINTAINERS: add me for the TCG plugins code, Alex Bennée, 2019/10/25
- [PULL v2 59/73] tests/plugin: add sample plugins, Alex Bennée, 2019/10/25
- [PULL v2 22/73] plugin: add user-facing API, Alex Bennée, 2019/10/25
- [PULL v2 12/73] travis.yml: cache the clang sanitizer build, Alex Bennée, 2019/10/25
- [PULL v2 21/73] docs/devel: add plugins.rst design document, Alex Bennée, 2019/10/25
- [PULL v2 65/73] tests/plugin: add a hotblocks plugin,
Alex Bennée <=
- [PULL v2 24/73] plugin: add implementation of the api, Alex Bennée, 2019/10/25
- [PULL v2 55/73] plugin: add qemu_plugin_insn_disas helper, Alex Bennée, 2019/10/25
- [PULL v2 40/73] target/arm: fetch code with translator_ld, Alex Bennée, 2019/10/25
- [PULL v2 52/73] configure: add --enable-plugins, Alex Bennée, 2019/10/25
- [PULL v2 28/73] tcg: add tcg_gen_st_ptr, Alex Bennée, 2019/10/25
- [PULL v2 71/73] scripts/checkpatch.pl: don't complain about (foo, /* empty */), Alex Bennée, 2019/10/25
- [PULL v2 36/73] cpu: hook plugin vcpu events, Alex Bennée, 2019/10/25
- [PULL v2 58/73] linux-user: support -plugin option, Alex Bennée, 2019/10/25
- [PULL v2 38/73] cputlb: ensure _cmmu helper functions follow the naming standard, Alex Bennée, 2019/10/25
- [PULL v2 18/73] trace: add mmu_index to mem_info, Alex Bennée, 2019/10/25