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authorAdam Litke <agl@us.ibm.com>2010-01-26 14:17:35 -0600
committerAnthony Liguori <aliguori@us.ibm.com>2010-01-26 17:08:03 -0600
commit625a5befc2e3200b396594f002218d235e375da5 (patch)
tree89b9362c879d319b5061424035e3dbead9555e70
parent940cc30d0d456781adcc48bf9f8c5582026d7983 (diff)
virtio: Add memory statistics reporting to the balloon driver
When using ballooning to manage overcommitted memory on a host, a system for guests to communicate their memory usage to the host can provide information that will minimize the impact of ballooning on the guests. The current method employs a daemon running in each guest that communicates memory statistics to a host daemon at a specified time interval. The host daemon aggregates this information and inflates and/or deflates balloons according to the level of host memory pressure. This approach is effective but overly complex since a daemon must be installed inside each guest and coordinated to communicate with the host. A simpler approach is to collect memory statistics in the virtio balloon driver and communicate them directly to the hypervisor. Signed-off-by: Adam Litke <agl@us.ibm.com> Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
-rw-r--r--balloon.h7
-rw-r--r--hw/virtio-balloon.c127
-rw-r--r--hw/virtio-balloon.h15
-rw-r--r--monitor.c98
-rw-r--r--qemu-monitor.hx3
-rw-r--r--vl.c21
6 files changed, 219 insertions, 52 deletions
diff --git a/balloon.h b/balloon.h
index 60b4a5de7..c3a1ad365 100644
--- a/balloon.h
+++ b/balloon.h
@@ -16,12 +16,13 @@
#include "cpu-defs.h"
-typedef ram_addr_t (QEMUBalloonEvent)(void *opaque, ram_addr_t target);
+typedef void (QEMUBalloonEvent)(void *opaque, ram_addr_t target,
+ MonitorCompletion cb, void *cb_data);
void qemu_add_balloon_handler(QEMUBalloonEvent *func, void *opaque);
-void qemu_balloon(ram_addr_t target);
+int qemu_balloon(ram_addr_t target, MonitorCompletion cb, void *opaque);
-ram_addr_t qemu_balloon_status(void);
+int qemu_balloon_status(MonitorCompletion cb, void *opaque);
#endif
diff --git a/hw/virtio-balloon.c b/hw/virtio-balloon.c
index e17880ff7..086d9d1ec 100644
--- a/hw/virtio-balloon.c
+++ b/hw/virtio-balloon.c
@@ -16,9 +16,13 @@
#include "pc.h"
#include "sysemu.h"
#include "cpu.h"
+#include "monitor.h"
#include "balloon.h"
#include "virtio-balloon.h"
#include "kvm.h"
+#include "qlist.h"
+#include "qint.h"
+#include "qstring.h"
#if defined(__linux__)
#include <sys/mman.h>
@@ -27,9 +31,14 @@
typedef struct VirtIOBalloon
{
VirtIODevice vdev;
- VirtQueue *ivq, *dvq;
+ VirtQueue *ivq, *dvq, *svq;
uint32_t num_pages;
uint32_t actual;
+ uint64_t stats[VIRTIO_BALLOON_S_NR];
+ VirtQueueElement stats_vq_elem;
+ size_t stats_vq_offset;
+ MonitorCompletion *stats_callback;
+ void *stats_opaque_callback_data;
} VirtIOBalloon;
static VirtIOBalloon *to_virtio_balloon(VirtIODevice *vdev)
@@ -46,6 +55,42 @@ static void balloon_page(void *addr, int deflate)
#endif
}
+/*
+ * reset_stats - Mark all items in the stats array as unset
+ *
+ * This function needs to be called at device intialization and before
+ * before updating to a set of newly-generated stats. This will ensure that no
+ * stale values stick around in case the guest reports a subset of the supported
+ * statistics.
+ */
+static inline void reset_stats(VirtIOBalloon *dev)
+{
+ int i;
+ for (i = 0; i < VIRTIO_BALLOON_S_NR; dev->stats[i++] = -1);
+}
+
+static void stat_put(QDict *dict, const char *label, uint64_t val)
+{
+ if (val != -1)
+ qdict_put(dict, label, qint_from_int(val));
+}
+
+static QObject *get_stats_qobject(VirtIOBalloon *dev)
+{
+ QDict *dict = qdict_new();
+ uint32_t actual = ram_size - (dev->actual << VIRTIO_BALLOON_PFN_SHIFT);
+
+ stat_put(dict, "actual", actual);
+ stat_put(dict, "mem_swapped_in", dev->stats[VIRTIO_BALLOON_S_SWAP_IN]);
+ stat_put(dict, "mem_swapped_out", dev->stats[VIRTIO_BALLOON_S_SWAP_OUT]);
+ stat_put(dict, "major_page_faults", dev->stats[VIRTIO_BALLOON_S_MAJFLT]);
+ stat_put(dict, "minor_page_faults", dev->stats[VIRTIO_BALLOON_S_MINFLT]);
+ stat_put(dict, "free_mem", dev->stats[VIRTIO_BALLOON_S_MEMFREE]);
+ stat_put(dict, "total_mem", dev->stats[VIRTIO_BALLOON_S_MEMTOT]);
+
+ return QOBJECT(dict);
+}
+
/* FIXME: once we do a virtio refactoring, this will get subsumed into common
* code */
static size_t memcpy_from_iovector(void *data, size_t offset, size_t size,
@@ -104,6 +149,51 @@ static void virtio_balloon_handle_output(VirtIODevice *vdev, VirtQueue *vq)
}
}
+static void complete_stats_request(VirtIOBalloon *vb)
+{
+ QObject *stats;
+
+ if (!vb->stats_opaque_callback_data)
+ return;
+
+ stats = get_stats_qobject(vb);
+ vb->stats_callback(vb->stats_opaque_callback_data, stats);
+ qobject_decref(stats);
+ vb->stats_opaque_callback_data = NULL;
+ vb->stats_callback = NULL;
+}
+
+static void virtio_balloon_receive_stats(VirtIODevice *vdev, VirtQueue *vq)
+{
+ VirtIOBalloon *s = DO_UPCAST(VirtIOBalloon, vdev, vdev);
+ VirtQueueElement *elem = &s->stats_vq_elem;
+ VirtIOBalloonStat stat;
+ size_t offset = 0;
+
+ if (!virtqueue_pop(vq, elem)) {
+ return;
+ }
+
+ /* Initialize the stats to get rid of any stale values. This is only
+ * needed to handle the case where a guest supports fewer stats than it
+ * used to (ie. it has booted into an old kernel).
+ */
+ reset_stats(s);
+
+ while (memcpy_from_iovector(&stat, offset, sizeof(stat), elem->out_sg,
+ elem->out_num) == sizeof(stat)) {
+ uint16_t tag = tswap16(stat.tag);
+ uint64_t val = tswap64(stat.val);
+
+ offset += sizeof(stat);
+ if (tag < VIRTIO_BALLOON_S_NR)
+ s->stats[tag] = val;
+ }
+ s->stats_vq_offset = offset;
+
+ complete_stats_request(s);
+}
+
static void virtio_balloon_get_config(VirtIODevice *vdev, uint8_t *config_data)
{
VirtIOBalloon *dev = to_virtio_balloon(vdev);
@@ -126,10 +216,12 @@ static void virtio_balloon_set_config(VirtIODevice *vdev,
static uint32_t virtio_balloon_get_features(VirtIODevice *vdev, uint32_t f)
{
+ f |= (1 << VIRTIO_BALLOON_F_STATS_VQ);
return f;
}
-static ram_addr_t virtio_balloon_to_target(void *opaque, ram_addr_t target)
+static void virtio_balloon_to_target(void *opaque, ram_addr_t target,
+ MonitorCompletion cb, void *cb_data)
{
VirtIOBalloon *dev = opaque;
@@ -139,9 +231,26 @@ static ram_addr_t virtio_balloon_to_target(void *opaque, ram_addr_t target)
if (target) {
dev->num_pages = (ram_size - target) >> VIRTIO_BALLOON_PFN_SHIFT;
virtio_notify_config(&dev->vdev);
+ } else {
+ /* For now, only allow one request at a time. This restriction can be
+ * removed later by queueing callback and data pairs.
+ */
+ if (dev->stats_callback != NULL) {
+ return;
+ }
+ dev->stats_callback = cb;
+ dev->stats_opaque_callback_data = cb_data;
+ if (dev->vdev.guest_features & (1 << VIRTIO_BALLOON_F_STATS_VQ)) {
+ virtqueue_push(dev->svq, &dev->stats_vq_elem, dev->stats_vq_offset);
+ virtio_notify(&dev->vdev, dev->svq);
+ } else {
+ /* Stats are not supported. Clear out any stale values that might
+ * have been set by a more featureful guest kernel.
+ */
+ reset_stats(dev);
+ complete_stats_request(dev);
+ }
}
-
- return ram_size - (dev->actual << VIRTIO_BALLOON_PFN_SHIFT);
}
static void virtio_balloon_save(QEMUFile *f, void *opaque)
@@ -152,6 +261,10 @@ static void virtio_balloon_save(QEMUFile *f, void *opaque)
qemu_put_be32(f, s->num_pages);
qemu_put_be32(f, s->actual);
+ qemu_put_buffer(f, (uint8_t *)&s->stats_vq_elem, sizeof(VirtQueueElement));
+ qemu_put_buffer(f, (uint8_t *)&s->stats_vq_offset, sizeof(size_t));
+ qemu_put_buffer(f, (uint8_t *)&s->stats_callback, sizeof(MonitorCompletion));
+ qemu_put_buffer(f, (uint8_t *)&s->stats_opaque_callback_data, sizeof(void));
}
static int virtio_balloon_load(QEMUFile *f, void *opaque, int version_id)
@@ -165,6 +278,10 @@ static int virtio_balloon_load(QEMUFile *f, void *opaque, int version_id)
s->num_pages = qemu_get_be32(f);
s->actual = qemu_get_be32(f);
+ qemu_get_buffer(f, (uint8_t *)&s->stats_vq_elem, sizeof(VirtQueueElement));
+ qemu_get_buffer(f, (uint8_t *)&s->stats_vq_offset, sizeof(size_t));
+ qemu_get_buffer(f, (uint8_t *)&s->stats_callback, sizeof(MonitorCompletion));
+ qemu_get_buffer(f, (uint8_t *)&s->stats_opaque_callback_data, sizeof(void));
return 0;
}
@@ -183,7 +300,9 @@ VirtIODevice *virtio_balloon_init(DeviceState *dev)
s->ivq = virtio_add_queue(&s->vdev, 128, virtio_balloon_handle_output);
s->dvq = virtio_add_queue(&s->vdev, 128, virtio_balloon_handle_output);
+ s->svq = virtio_add_queue(&s->vdev, 128, virtio_balloon_receive_stats);
+ reset_stats(s);
qemu_add_balloon_handler(virtio_balloon_to_target, s);
register_savevm("virtio-balloon", -1, 1, virtio_balloon_save, virtio_balloon_load, s);
diff --git a/hw/virtio-balloon.h b/hw/virtio-balloon.h
index 9a0d119e4..e20cf6bc0 100644
--- a/hw/virtio-balloon.h
+++ b/hw/virtio-balloon.h
@@ -25,6 +25,7 @@
/* The feature bitmap for virtio balloon */
#define VIRTIO_BALLOON_F_MUST_TELL_HOST 0 /* Tell before reclaiming pages */
+#define VIRTIO_BALLOON_F_STATS_VQ 1 /* Memory stats virtqueue */
/* Size of a PFN in the balloon interface. */
#define VIRTIO_BALLOON_PFN_SHIFT 12
@@ -37,4 +38,18 @@ struct virtio_balloon_config
uint32_t actual;
};
+/* Memory Statistics */
+#define VIRTIO_BALLOON_S_SWAP_IN 0 /* Amount of memory swapped in */
+#define VIRTIO_BALLOON_S_SWAP_OUT 1 /* Amount of memory swapped out */
+#define VIRTIO_BALLOON_S_MAJFLT 2 /* Number of major faults */
+#define VIRTIO_BALLOON_S_MINFLT 3 /* Number of minor faults */
+#define VIRTIO_BALLOON_S_MEMFREE 4 /* Total amount of free memory */
+#define VIRTIO_BALLOON_S_MEMTOT 5 /* Total amount of memory */
+#define VIRTIO_BALLOON_S_NR 6
+
+typedef struct VirtIOBalloonStat {
+ uint16_t tag;
+ uint64_t val;
+} __attribute__((packed)) VirtIOBalloonStat;
+
#endif
diff --git a/monitor.c b/monitor.c
index be34329cf..fbae5ce09 100644
--- a/monitor.c
+++ b/monitor.c
@@ -2152,33 +2152,13 @@ static void do_info_status(Monitor *mon, QObject **ret_data)
vm_running, singlestep);
}
-static ram_addr_t balloon_get_value(void)
+static void print_balloon_stat(const char *key, QObject *obj, void *opaque)
{
- ram_addr_t actual;
-
- if (kvm_enabled() && !kvm_has_sync_mmu()) {
- qemu_error_new(QERR_KVM_MISSING_CAP, "synchronous MMU", "balloon");
- return 0;
- }
-
- actual = qemu_balloon_status();
- if (actual == 0) {
- qemu_error_new(QERR_DEVICE_NOT_ACTIVE, "balloon");
- return 0;
- }
-
- return actual;
-}
+ Monitor *mon = opaque;
-/**
- * do_balloon(): Request VM to change its memory allocation
- */
-static void do_balloon(Monitor *mon, const QDict *qdict, QObject **ret_data)
-{
- if (balloon_get_value()) {
- /* ballooning is active */
- qemu_balloon(qdict_get_int(qdict, "value"));
- }
+ if (strcmp(key, "actual"))
+ monitor_printf(mon, ",%s=%" PRId64, key,
+ qint_get_int(qobject_to_qint(obj)));
}
static void monitor_print_balloon(Monitor *mon, const QObject *data)
@@ -2186,31 +2166,74 @@ static void monitor_print_balloon(Monitor *mon, const QObject *data)
QDict *qdict;
qdict = qobject_to_qdict(data);
+ if (!qdict_haskey(qdict, "actual"))
+ return;
- monitor_printf(mon, "balloon: actual=%" PRId64 "\n",
- qdict_get_int(qdict, "balloon") >> 20);
+ monitor_printf(mon, "balloon: actual=%" PRId64,
+ qdict_get_int(qdict, "actual") >> 20);
+ qdict_iter(qdict, print_balloon_stat, mon);
+ monitor_printf(mon, "\n");
}
/**
* do_info_balloon(): Balloon information
*
- * Return a QDict with the following information:
+ * Make an asynchronous request for balloon info. When the request completes
+ * a QDict will be returned according to the following specification:
*
- * - "balloon": current balloon value in bytes
+ * - "actual": current balloon value in bytes
+ * The following fields may or may not be present:
+ * - "mem_swapped_in": Amount of memory swapped in (bytes)
+ * - "mem_swapped_out": Amount of memory swapped out (bytes)
+ * - "major_page_faults": Number of major faults
+ * - "minor_page_faults": Number of minor faults
+ * - "free_mem": Total amount of free and unused memory (bytes)
+ * - "total_mem": Total amount of available memory (bytes)
*
* Example:
*
- * { "balloon": 1073741824 }
+ * { "actual": 1073741824, "mem_swapped_in": 0, "mem_swapped_out": 0,
+ * "major_page_faults": 142, "minor_page_faults": 239245,
+ * "free_mem": 1014185984, "total_mem": 1044668416 }
+ */
+static int do_info_balloon(Monitor *mon, MonitorCompletion cb, void *opaque)
+{
+ int ret;
+
+ if (kvm_enabled() && !kvm_has_sync_mmu()) {
+ qemu_error_new(QERR_KVM_MISSING_CAP, "synchronous MMU", "balloon");
+ return -1;
+ }
+
+ ret = qemu_balloon_status(cb, opaque);
+ if (!ret) {
+ qemu_error_new(QERR_DEVICE_NOT_ACTIVE, "balloon");
+ return -1;
+ }
+
+ return 0;
+}
+
+/**
+ * do_balloon(): Request VM to change its memory allocation
*/
-static void do_info_balloon(Monitor *mon, QObject **ret_data)
+static int do_balloon(Monitor *mon, const QDict *params,
+ MonitorCompletion cb, void *opaque)
{
- ram_addr_t actual;
+ int ret;
+
+ if (kvm_enabled() && !kvm_has_sync_mmu()) {
+ qemu_error_new(QERR_KVM_MISSING_CAP, "synchronous MMU", "balloon");
+ return -1;
+ }
- actual = balloon_get_value();
- if (actual != 0) {
- *ret_data = qobject_from_jsonf("{ 'balloon': %" PRId64 "}",
- (int64_t) actual);
+ ret = qemu_balloon(qdict_get_int(params, "value"), cb, opaque);
+ if (ret == 0) {
+ qemu_error_new(QERR_DEVICE_NOT_ACTIVE, "balloon");
+ return -1;
}
+
+ return 0;
}
static qemu_acl *find_acl(Monitor *mon, const char *name)
@@ -2696,7 +2719,8 @@ static const mon_cmd_t info_cmds[] = {
.params = "",
.help = "show balloon information",
.user_print = monitor_print_balloon,
- .mhandler.info_new = do_info_balloon,
+ .mhandler.info_async = do_info_balloon,
+ .async = 1,
},
{
.name = "qtree",
diff --git a/qemu-monitor.hx b/qemu-monitor.hx
index 415734a46..b51bb47f2 100644
--- a/qemu-monitor.hx
+++ b/qemu-monitor.hx
@@ -891,7 +891,8 @@ ETEXI
.params = "target",
.help = "request VM to change it's memory allocation (in MB)",
.user_print = monitor_user_noop,
- .mhandler.cmd_new = do_balloon,
+ .mhandler.cmd_async = do_balloon,
+ .async = 1,
},
STEXI
diff --git a/vl.c b/vl.c
index 5e8c77508..1cd355c69 100644
--- a/vl.c
+++ b/vl.c
@@ -365,17 +365,24 @@ void qemu_add_balloon_handler(QEMUBalloonEvent *func, void *opaque)
qemu_balloon_event_opaque = opaque;
}
-void qemu_balloon(ram_addr_t target)
+int qemu_balloon(ram_addr_t target, MonitorCompletion cb, void *opaque)
{
- if (qemu_balloon_event)
- qemu_balloon_event(qemu_balloon_event_opaque, target);
+ if (qemu_balloon_event) {
+ qemu_balloon_event(qemu_balloon_event_opaque, target, cb, opaque);
+ return 1;
+ } else {
+ return 0;
+ }
}
-ram_addr_t qemu_balloon_status(void)
+int qemu_balloon_status(MonitorCompletion cb, void *opaque)
{
- if (qemu_balloon_event)
- return qemu_balloon_event(qemu_balloon_event_opaque, 0);
- return 0;
+ if (qemu_balloon_event) {
+ qemu_balloon_event(qemu_balloon_event_opaque, 0, cb, opaque);
+ return 1;
+ } else {
+ return 0;
+ }
}