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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>
This commit is contained in:
Adam Litke 2010-01-26 14:17:35 -06:00 committed by Anthony Liguori
parent 940cc30d0d
commit 625a5befc2
6 changed files with 219 additions and 52 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

7
balloon.h
View File

@ -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

127
hw/virtio-balloon.c
View File

@ -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);

15
hw/virtio-balloon.h
View File

@ -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

98
monitor.c
View File

@ -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;
Monitor *mon = opaque;
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;
}
/**
* 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 void do_info_balloon(Monitor *mon, QObject **ret_data)
static int do_info_balloon(Monitor *mon, MonitorCompletion cb, void *opaque)
{
ram_addr_t actual;
int ret;
actual = balloon_get_value();
if (actual != 0) {
*ret_data = qobject_from_jsonf("{ 'balloon': %" PRId64 "}",
(int64_t) actual);
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 int do_balloon(Monitor *mon, const QDict *params,
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(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",

3
qemu-monitor.hx
View File

@ -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

21
vl.c
View File

@ -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;
}
}