[Qemu-devel] [RFC 2/3] qga: implement get-memory-info for Linux

[marcandre.lureau@redhat.com]

From: Marc-André Lureau <marcandre.lureau@redhat.com>

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
---
 qga/commands-posix.c | 94 ++++++++++++++++++++++++++++++++++++++++++++++++++--
 qga/main.c           | 28 ++++++++++++++++
 2 files changed, 120 insertions(+), 2 deletions(-)

diff --git a/qga/commands-posix.c b/qga/commands-posix.c
index eb4036e..9534c2d 100644
--- a/qga/commands-posix.c
+++ b/qga/commands-posix.c
@@ -28,6 +28,7 @@
 #include "qapi/qmp/qerror.h"
 #include "qemu/queue.h"
 #include "qemu/host-utils.h"
+#include "glib-compat.h"
 
 #ifndef CONFIG_HAS_ENVIRON
 #ifdef __APPLE__
@@ -2328,10 +2329,99 @@ GuestMemoryBlockInfo *qmp_guest_get_memory_block_info(Error **errp)
     return info;
 }
 
+static long meminfo_value(gchar * const *col)
+{
+    int i;
+
+    g_return_val_if_fail(col && col[0], 0);
+
+    for (i = 1; col[i]; i++) {
+        if (strlen(col[i]) > 0) {
+            return g_ascii_strtoll(col[i], NULL, 10);
+        }
+    }
+
+    g_return_val_if_reached(0);
+}
+
 GuestMemoryInfo *qmp_guest_get_memory_info(Error **errp)
 {
-    error_setg(errp, QERR_UNSUPPORTED);
-    return NULL;
+    static guint64 last_time, last_swap_in, last_swap_out;
+    static guint64 last_pf_major, last_pf_minor;
+    GError *err = NULL;
+    GuestMemoryInfo *info;
+    gchar *contents = NULL;
+    gchar **lines;
+    int i;
+    guint64 time;
+
+    if (!g_file_get_contents("/proc/meminfo", &contents, NULL, &err)) {
+        error_setg(errp, "unable to read meminfo: %s", err->message);
+        g_clear_error(&err);
+        return NULL;
+    }
+
+    info = g_new0(GuestMemoryInfo, 1);
+
+    lines = g_strsplit(contents, "\n", -1);
+    for (i = 0; lines[i]; i++) {
+        gchar **col = g_strsplit(lines[i], " ", -1);
+        if (g_strcmp0(col[0], "MemTotal:") == 0) {
+            info->mem_total = meminfo_value(col);
+        } else if (g_strcmp0(col[0], "MemAvailable:") == 0) {
+            /* available since kernel 3.2 */
+            info->mem_free = meminfo_value(col);
+        } else if (g_strcmp0(col[0], "Cached:") == 0) {
+            info->mem_cached = meminfo_value(col);
+        } else if (g_strcmp0(col[0], "SwapTotal:") == 0) {
+            info->swap_total = meminfo_value(col);
+        } else if (g_strcmp0(col[0], "SwapFree:") == 0) {
+            info->swap_free = meminfo_value(col);
+        }
+        g_strfreev(col);
+    }
+    g_strfreev(lines);
+
+    g_free(contents);
+
+    if (!g_file_get_contents("/proc/vmstat", &contents, NULL, &err)) {
+        error_setg(errp, "unable to read meminfo: %s", err->message);
+        g_clear_error(&err);
+        g_free(info);
+        return NULL;
+    }
+
+    time = g_get_monotonic_time();
+    double elapsed = (time - last_time + 1) / (double)G_USEC_PER_SEC;
+
+#define UPDATE(Field) do {                              \
+    guint64 val = g_ascii_strtoll(col[1], NULL, 10);    \
+    info->Field = (val - last_ ##Field) / elapsed;      \
+    last_ ##Field = val;                                \
+} while (0)
+
+    lines = g_strsplit(contents, "\n", -1);
+    for (i = 0; lines[i]; i++) {
+        gchar **col = g_strsplit(lines[i], " ", -1);
+        if (g_strcmp0(col[0], "pswpin") == 0) {
+            UPDATE(swap_in);
+        } else if (g_strcmp0(col[0], "pswpout") == 0) {
+            UPDATE(swap_out);
+        } else if (g_strcmp0(col[0], "pgfault") == 0) {
+            UPDATE(pf_minor);
+        } else if (g_strcmp0(col[0], "pgmajfault") == 0) {
+            UPDATE(pf_major);
+        }
+        g_strfreev(col);
+    }
+    g_strfreev(lines);
+
+#undef UPDATE
+
+    last_time = time;
+    g_free(contents);
+
+    return info;
 }
 
 #else /* defined(__linux__) */
diff --git a/qga/main.c b/qga/main.c
index aef007b..4790e26 100644
--- a/qga/main.c
+++ b/qga/main.c
@@ -42,6 +42,7 @@
 #define CONFIG_FSFREEZE
 #endif
 #endif
+#include "qga-qmp-commands.h"
 
 #ifndef _WIN32
 #define QGA_VIRTIO_PATH_DEFAULT "/dev/virtio-ports/org.qemu.guest_agent.0"
@@ -901,6 +902,31 @@ int64_t ga_get_fd_handle(GAState *s, Error **errp)
     return handle;
 }
 
+static void initialize_memory_stats(void)
+{
+    GuestMemoryInfo *info = qmp_guest_get_memory_info(NULL);
+
+    if (!info) {
+        return;
+    }
+
+    /* just for checking at start if everything looks ok */
+    g_debug("mem-total: %" G_GUINT64_FORMAT " kB\n"
+            "mem-free: %" G_GUINT64_FORMAT " kB\n"
+            "mem-cached: %" G_GUINT64_FORMAT " kB\n"
+            "swap-total: %" G_GUINT64_FORMAT " kB\n"
+            "swap-free: %" G_GUINT64_FORMAT " kB\n"
+            "swap-in: %" G_GUINT64_FORMAT " kB\n"
+            "swap-out: %" G_GUINT64_FORMAT " kB\n"
+            "pf-major: %" G_GUINT64_FORMAT " kB\n"
+            "pf-minor: %" G_GUINT64_FORMAT " kB\n",
+            info->mem_total, info->mem_free, info->mem_cached,
+            info->swap_total, info->swap_free, info->swap_in, info->swap_out,
+            info->pf_major, info->pf_minor);
+
+    g_free(info);
+}
+
 static void ga_print_cmd(QmpCommand *cmd, void *opaque)
 {
     printf("%s\n", qmp_command_name(cmd));
@@ -1256,6 +1282,8 @@ static int run_agent(GAState *s)
     }
 #endif
 
+    initialize_memory_stats();
+
     s->main_loop = g_main_loop_new(NULL, false);
     if (!channel_init(ga_state, method, device_path)) {
         g_critical("failed to initialize guest agent channel");
-- 
2.4.3