[Qemu-devel] [PATCH v4 51/54] tests/plugin: add hotpages plugin to breakdown memory access patterns

["Alex Bennée" <alex.bennee@linaro.org>]

This plugin gives a break down of access patterns grouped into pages.

Signed-off-by: Alex Bennée <alex.bennee@linaro.org>

---
v4
   - tweaks for new hwaddr api
   - add sorting and pagesize selection args
---
 tests/plugin/Makefile   |   1 +
 tests/plugin/hotpages.c | 179 ++++++++++++++++++++++++++++++++++++++++
 2 files changed, 180 insertions(+)
 create mode 100644 tests/plugin/hotpages.c

diff --git a/tests/plugin/Makefile b/tests/plugin/Makefile
index 3656429d46b..75467b6db85 100644
--- a/tests/plugin/Makefile
+++ b/tests/plugin/Makefile
@@ -12,6 +12,7 @@ NAMES += insn
 NAMES += mem
 NAMES += hotblocks
 NAMES += howvec
+NAMES += hotpages
 
 SONAMES := $(addsuffix .so,$(addprefix lib,$(NAMES)))
 
diff --git a/tests/plugin/hotpages.c b/tests/plugin/hotpages.c
new file mode 100644
index 00000000000..13ce8ffeb8b
--- /dev/null
+++ b/tests/plugin/hotpages.c
@@ -0,0 +1,179 @@
+/*
+ * Copyright (C) 2019, Alex Bennée <alex.bennee@linaro.org>
+ *
+ * Hot Pages - show which pages saw the most memory accesses.
+ *
+ * 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>
+
+#define ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0]))
+
+static uint64_t page_size = 4096;
+static uint64_t page_mask;
+static int stdout_fd;
+static int limit = 50;
+static enum qemu_plugin_mem_rw rw = QEMU_PLUGIN_MEM_RW;
+
+enum sort_type {
+    SORT_RW = 0,
+    SORT_R,
+    SORT_W
+};
+
+static int sort_by = SORT_RW;
+
+typedef struct {
+    uint64_t page_address;
+    int cpu_read;
+    int cpu_write;
+    uint64_t reads;
+    uint64_t writes;
+} PageCounters;
+
+static GMutex lock;
+static GHashTable *pages;
+
+static gint cmp_access_count(gconstpointer a, gconstpointer b)
+{
+    PageCounters *ea = (PageCounters *) a;
+    PageCounters *eb = (PageCounters *) b;
+    int r;
+    switch (sort_by) {
+    case SORT_RW:
+        r = (ea->reads + ea->writes) > (eb->reads + eb->writes) ? -1 : 1;
+        break;
+    case SORT_R:
+        r = ea->reads > eb->reads ? -1 : 1;
+        break;
+    case SORT_W:
+        r = ea->writes > eb->writes ? -1 : 1;
+        break;
+    default:
+        g_assert_not_reached();
+    }
+    return r;
+}
+
+
+static void plugin_exit(qemu_plugin_id_t id, void *p)
+{
+    GString *report = g_string_new("Addr, RCPUs, Reads, WCPUs, Writes\n");
+    int i;
+    GList *counts;
+
+    counts = g_hash_table_get_values(pages);
+    if (counts && g_list_next(counts)) {
+        GList *it;
+
+        it = g_list_sort(counts, cmp_access_count);
+
+        for (i = 0; i < limit && it->next; i++, it = it->next) {
+            PageCounters *rec = (PageCounters *) it->data;
+            g_string_append_printf(report,
+                                   "%#016"PRIx64", 0x%04x, %"PRId64
+                                   ", 0x%04x, %"PRId64"\n",
+                                   rec->page_address,
+                                   rec->cpu_read, rec->reads,
+                                   rec->cpu_write, rec->writes);
+        }
+        g_list_free(it);
+    }
+
+    dprintf(stdout_fd, "%s", report->str);
+    g_string_free(report, true);
+}
+
+static void plugin_init(void)
+{
+    page_mask = (page_size - 1);
+    pages = g_hash_table_new(NULL, g_direct_equal);
+}
+
+static void vcpu_haddr(unsigned int cpu_index, qemu_plugin_meminfo_t meminfo,
+                       uint64_t vaddr, void *udata)
+{
+    struct qemu_plugin_hwaddr *hwaddr = qemu_plugin_get_hwaddr(meminfo, vaddr);
+    uint64_t page;
+    PageCounters *count;
+
+    /* We only get a hwaddr for system emulation */
+    if (hwaddr) {
+        page = (uint64_t) qemu_plugin_hwaddr_to_raddr(hwaddr);
+    } else {
+        page = vaddr;
+    }
+    page &= ~page_mask;
+
+    g_mutex_lock(&lock);
+    count = (PageCounters *) g_hash_table_lookup(pages, GUINT_TO_POINTER(page));
+
+    if (!count) {
+        count = g_new0(PageCounters, 1);
+        count->page_address = page;
+        g_hash_table_insert(pages, GUINT_TO_POINTER(page), (gpointer) count);
+    }
+    if (qemu_plugin_mem_is_store(meminfo)) {
+        count->writes++;
+        count->cpu_write |= (1 << cpu_index);
+    } else {
+        count->reads++;
+        count->cpu_read |= (1 << cpu_index);
+    }
+
+    g_mutex_unlock(&lock);
+}
+
+static void vcpu_tb_trans(qemu_plugin_id_t id, struct qemu_plugin_tb *tb)
+{
+    size_t n = qemu_plugin_tb_n_insns(tb);
+    size_t i;
+
+    for (i = 0; i < n; i++) {
+        struct qemu_plugin_insn *insn = qemu_plugin_tb_get_insn(tb, i);
+        qemu_plugin_register_vcpu_mem_cb(insn, vcpu_haddr,
+                                         QEMU_PLUGIN_CB_NO_REGS,
+                                         rw, NULL);
+    }
+}
+
+QEMU_PLUGIN_EXPORT int qemu_plugin_install(qemu_plugin_id_t id, int argc,
+                                           char **argv)
+{
+    int i;
+
+    /* to be used when in the exit hook */
+    stdout_fd = dup(STDOUT_FILENO);
+    assert(stdout_fd);
+
+    for (i = 0; i < argc; i++) {
+        char *opt = argv[i];
+        if (g_strcmp0(opt, "reads") == 0) {
+            sort_by = SORT_R;
+        } else if (g_strcmp0(opt, "writes") == 0) {
+            sort_by = SORT_W;
+        } else if (g_str_has_prefix(opt, "pagesize=")) {
+            page_size = g_ascii_strtoull(opt + 9, NULL, 10);
+        } else {
+            dprintf(stdout_fd, "option parsing failed: %s\n", opt);
+            return -1;
+        }
+    }
+
+    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