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[PATCH v5 45/55] tests/plugin: add a hotblocks plugin
From: |
Alex Bennée |
Subject: |
[PATCH v5 45/55] tests/plugin: add a hotblocks plugin |
Date: |
Mon, 14 Oct 2019 11:49:38 +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>
---
v5
- handle 0 length report
---
tests/plugin/Makefile | 1 +
tests/plugin/hotblocks.c | 148 +++++++++++++++++++++++++++++++++++++++
2 files changed, 149 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..a150179a5c
--- /dev/null
+++ b/tests/plugin/hotblocks.c
@@ -0,0 +1,148 @@
+/*
+ * 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;
+static int stdout_fd;
+
+/* 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)
+{
+ 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);
+ }
+
+ dprintf(stdout_fd, "%s", report->str);
+ g_string_free(report, true);
+}
+
+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, int argc,
+ char **argv)
+{
+ if (argc && strcmp(argv[0], "inline") == 0) {
+ do_inline = true;
+ }
+
+ /* to be used when in the exit hook */
+ stdout_fd = dup(STDOUT_FILENO);
+ assert(stdout_fd);
+
+ 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
- Re: [PATCH v5 17/55] plugins: implement helpers for resolving hwaddr, (continued)
[PATCH v5 32/55] target/sparc: fetch code with translator_ld, Alex Bennée, 2019/10/14
[PATCH v5 18/55] translate-all: notify plugin code of tb_flush, Alex Bennée, 2019/10/14
[PATCH v5 30/55] target/alpha: fetch code with translator_ld, Alex Bennée, 2019/10/14
[PATCH v5 13/55] tcg: add tcg_gen_st_ptr, Alex Bennée, 2019/10/14
[PATCH v5 42/55] tests/tcg: move "virtual" tests to EXTRA_TESTS, Alex Bennée, 2019/10/14
[PATCH v5 45/55] tests/plugin: add a hotblocks plugin,
Alex Bennée <=
[PATCH v5 29/55] target/m68k: fetch code with translator_ld, Alex Bennée, 2019/10/14
[PATCH v5 26/55] target/sh4: fetch code with translator_ld, Alex Bennée, 2019/10/14
[PATCH v5 48/55] tests/plugin: add hotpages plugin to breakdown memory access patterns, Alex Bennée, 2019/10/14
[PATCH v5 16/55] tcg: let plugins instrument virtual memory accesses, Alex Bennée, 2019/10/14
[PATCH v5 14/55] plugin-gen: add module for TCG-related code, Alex Bennée, 2019/10/14
[PATCH v5 35/55] translator: inject instrumentation from plugins, Alex Bennée, 2019/10/14
[PATCH v5 28/55] target/hppa: fetch code with translator_ld, Alex Bennée, 2019/10/14