Changes since V3:
- Do not do endian conversions as they will be done in the host
- Report stats that reference a quantity of memory in bytes
- Minor coding style updates
Changes since V2:
- Increase stat field size to 64 bits
- Report all sizes in kb (not pages)
- Drop anon_pages stat and fix endianness conversion
Changes since V1:
- Use a virtqueue instead of the device config space
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.
This patch enables the guest-side support by adding stats collection and
reporting to the virtio balloon driver.
Signed-off-by: Adam Litke <[email protected]>
Cc: Rusty Russell <[email protected]>
Cc: Anthony Liguori <[email protected]>
Cc: [email protected]
Cc: [email protected]
diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c
index 200c22f..f4c8cd8 100644
--- a/drivers/virtio/virtio_balloon.c
+++ b/drivers/virtio/virtio_balloon.c
@@ -29,7 +29,7 @@
struct virtio_balloon
{
struct virtio_device *vdev;
- struct virtqueue *inflate_vq, *deflate_vq;
+ struct virtqueue *inflate_vq, *deflate_vq, *stats_vq;
/* Where the ballooning thread waits for config to change. */
wait_queue_head_t config_change;
@@ -50,6 +50,9 @@ struct virtio_balloon
/* The array of pfns we tell the Host about. */
unsigned int num_pfns;
u32 pfns[256];
+
+ /* Memory statistics */
+ struct virtio_balloon_stat stats[VIRTIO_BALLOON_S_NR];
};
static struct virtio_device_id id_table[] = {
@@ -155,6 +158,61 @@ static void leak_balloon(struct virtio_balloon *vb, size_t num)
}
}
+static inline void update_stat(struct virtio_balloon *vb, int idx,
+ __le16 tag, __le64 val)
+{
+ BUG_ON(idx >= VIRTIO_BALLOON_S_NR);
+ vb->stats[idx].tag = tag;
+ vb->stats[idx].val = val;
+}
+
+#define pages_to_bytes(x) ((x) << PAGE_SHIFT)
+static void update_balloon_stats(struct virtio_balloon *vb)
+{
+ unsigned long events[NR_VM_EVENT_ITEMS];
+ struct sysinfo i;
+ int idx = 0;
+
+ all_vm_events(events);
+ si_meminfo(&i);
+
+ update_stat(vb, idx++, VIRTIO_BALLOON_S_SWAP_IN,
+ pages_to_bytes(events[PSWPIN]));
+ update_stat(vb, idx++, VIRTIO_BALLOON_S_SWAP_OUT,
+ pages_to_bytes(events[PSWPOUT]));
+ update_stat(vb, idx++, VIRTIO_BALLOON_S_MAJFLT, events[PGMAJFAULT]);
+ update_stat(vb, idx++, VIRTIO_BALLOON_S_MINFLT, events[PGFAULT]);
+ update_stat(vb, idx++, VIRTIO_BALLOON_S_MEMFREE,
+ pages_to_bytes(i.freeram));
+ update_stat(vb, idx++, VIRTIO_BALLOON_S_MEMTOT,
+ pages_to_bytes(i.totalram));
+}
+
+/*
+ * While most virtqueues communicate guest-initiated requests to the hypervisor,
+ * the stats queue operates in reverse. The driver initializes the virtqueue
+ * with a single buffer. From that point forward, all conversations consist of
+ * a hypervisor request (a call to this function) which directs us to refill
+ * the virtqueue with a fresh stats buffer.
+ */
+static void stats_ack(struct virtqueue *vq)
+{
+ struct virtio_balloon *vb;
+ unsigned int len;
+ struct scatterlist sg;
+
+ vb = vq->vq_ops->get_buf(vq, &len);
+ if (!vb)
+ return;
+
+ update_balloon_stats(vb);
+
+ sg_init_one(&sg, vb->stats, sizeof(vb->stats));
+ if (vq->vq_ops->add_buf(vq, &sg, 1, 0, vb) < 0)
+ BUG();
+ vq->vq_ops->kick(vq);
+}
+
static void virtballoon_changed(struct virtio_device *vdev)
{
struct virtio_balloon *vb = vdev->priv;
@@ -205,10 +263,10 @@ static int balloon(void *_vballoon)
static int virtballoon_probe(struct virtio_device *vdev)
{
struct virtio_balloon *vb;
- struct virtqueue *vqs[2];
- vq_callback_t *callbacks[] = { balloon_ack, balloon_ack };
- const char *names[] = { "inflate", "deflate" };
- int err;
+ struct virtqueue *vqs[3];
+ vq_callback_t *callbacks[] = { balloon_ack, balloon_ack, stats_ack };
+ const char *names[] = { "inflate", "deflate", "stats" };
+ int err, nvqs;
vdev->priv = vb = kmalloc(sizeof(*vb), GFP_KERNEL);
if (!vb) {
@@ -221,13 +279,28 @@ static int virtballoon_probe(struct virtio_device *vdev)
init_waitqueue_head(&vb->config_change);
vb->vdev = vdev;
- /* We expect two virtqueues. */
- err = vdev->config->find_vqs(vdev, 2, vqs, callbacks, names);
+ /* We expect two virtqueues: inflate and deflate,
+ * and optionally stat. */
+ nvqs = virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_STATS_VQ) ? 3 : 2;
+ err = vdev->config->find_vqs(vdev, nvqs, vqs, callbacks, names);
if (err)
goto out_free_vb;
vb->inflate_vq = vqs[0];
vb->deflate_vq = vqs[1];
+ if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_STATS_VQ)) {
+ struct scatterlist sg;
+ vb->stats_vq = vqs[2];
+
+ /*
+ * Prime this virtqueue with one buffer so the hypervisor can
+ * use it to signal us later.
+ */
+ sg_init_one(&sg, vb->stats, sizeof vb->stats);
+ if (vb->stats_vq->vq_ops->add_buf(vb->stats_vq, &sg, 1, 0, vb) < 0)
+ BUG();
+ vb->stats_vq->vq_ops->kick(vb->stats_vq);
+ }
vb->thread = kthread_run(balloon, vb, "vballoon");
if (IS_ERR(vb->thread)) {
@@ -265,7 +338,10 @@ static void virtballoon_remove(struct virtio_device *vdev)
kfree(vb);
}
-static unsigned int features[] = { VIRTIO_BALLOON_F_MUST_TELL_HOST };
+static unsigned int features[] = {
+ VIRTIO_BALLOON_F_MUST_TELL_HOST,
+ VIRTIO_BALLOON_F_STATS_VQ,
+};
static struct virtio_driver virtio_balloon = {
.feature_table = features,
diff --git a/include/linux/virtio_balloon.h b/include/linux/virtio_balloon.h
index 09d7300..92d3550 100644
--- a/include/linux/virtio_balloon.h
+++ b/include/linux/virtio_balloon.h
@@ -6,6 +6,7 @@
/* 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
@@ -17,4 +18,19 @@ struct virtio_balloon_config
/* Number of pages we've actually got in balloon. */
__le32 actual;
};
+
+#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
+
+struct virtio_balloon_stat
+{
+ u16 tag;
+ u64 val;
+} __attribute__((packed));
+
#endif /* _LINUX_VIRTIO_BALLOON_H */
--
Thanks,
Adam
On Tue, 1 Dec 2009 02:44:15 am Adam Litke wrote:
> Changes since V3:
OK, I applied this. And here's the fixes I applied afterwards (to save YA
round trip: please ack and I'll fold them together)
virtio: balloon fixes
1) Tag and val args to update_stat() are no longer __le.
2) pages_to_bytes() should promote to u64 so we don't truncate.
3) Fix two checkpatch.pl warnings.
Signed-off-by: Rusty Russell <[email protected]>
---
drivers/virtio/virtio_balloon.c | 8 +++++---
include/linux/virtio_balloon.h | 3 +--
2 files changed, 6 insertions(+), 5 deletions(-)
diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c
--- a/drivers/virtio/virtio_balloon.c
+++ b/drivers/virtio/virtio_balloon.c
@@ -158,14 +158,15 @@ static void leak_balloon(struct virtio_b
}
static inline void update_stat(struct virtio_balloon *vb, int idx,
- __le16 tag, __le64 val)
+ u16 tag, u64 val)
{
BUG_ON(idx >= VIRTIO_BALLOON_S_NR);
vb->stats[idx].tag = tag;
vb->stats[idx].val = val;
}
-#define pages_to_bytes(x) ((x) << PAGE_SHIFT)
+#define pages_to_bytes(x) ((u64)(x) << PAGE_SHIFT)
+
static void update_balloon_stats(struct virtio_balloon *vb)
{
unsigned long events[NR_VM_EVENT_ITEMS];
@@ -296,7 +297,8 @@ static int virtballoon_probe(struct virt
* use it to signal us later.
*/
sg_init_one(&sg, vb->stats, sizeof vb->stats);
- if (vb->stats_vq->vq_ops->add_buf(vb->stats_vq, &sg, 1, 0, vb) < 0)
+ if (vb->stats_vq->vq_ops->add_buf(vb->stats_vq,
+ &sg, 1, 0, vb) < 0)
BUG();
vb->stats_vq->vq_ops->kick(vb->stats_vq);
}
diff --git a/include/linux/virtio_balloon.h b/include/linux/virtio_balloon.h
--- a/include/linux/virtio_balloon.h
+++ b/include/linux/virtio_balloon.h
@@ -28,8 +28,7 @@ struct virtio_balloon_config
#define VIRTIO_BALLOON_S_MEMTOT 5 /* Total amount of memory */
#define VIRTIO_BALLOON_S_NR 6
-struct virtio_balloon_stat
-{
+struct virtio_balloon_stat {
u16 tag;
u64 val;
} __attribute__((packed));
Thanks Rusty.
Acked-by: Adam Litke <[email protected]>
On Tue, 2009-12-01 at 12:54 +1030, Rusty Russell wrote:
> On Tue, 1 Dec 2009 02:44:15 am Adam Litke wrote:
> > Changes since V3:
>
> OK, I applied this. And here's the fixes I applied afterwards (to save YA
> round trip: please ack and I'll fold them together)
>
> virtio: balloon fixes
>
> 1) Tag and val args to update_stat() are no longer __le.
> 2) pages_to_bytes() should promote to u64 so we don't truncate.
> 3) Fix two checkpatch.pl warnings.
>
> Signed-off-by: Rusty Russell <[email protected]>
> ---
> drivers/virtio/virtio_balloon.c | 8 +++++---
> include/linux/virtio_balloon.h | 3 +--
> 2 files changed, 6 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c
> --- a/drivers/virtio/virtio_balloon.c
> +++ b/drivers/virtio/virtio_balloon.c
> @@ -158,14 +158,15 @@ static void leak_balloon(struct virtio_b
> }
>
> static inline void update_stat(struct virtio_balloon *vb, int idx,
> - __le16 tag, __le64 val)
> + u16 tag, u64 val)
> {
> BUG_ON(idx >= VIRTIO_BALLOON_S_NR);
> vb->stats[idx].tag = tag;
> vb->stats[idx].val = val;
> }
>
> -#define pages_to_bytes(x) ((x) << PAGE_SHIFT)
> +#define pages_to_bytes(x) ((u64)(x) << PAGE_SHIFT)
> +
> static void update_balloon_stats(struct virtio_balloon *vb)
> {
> unsigned long events[NR_VM_EVENT_ITEMS];
> @@ -296,7 +297,8 @@ static int virtballoon_probe(struct virt
> * use it to signal us later.
> */
> sg_init_one(&sg, vb->stats, sizeof vb->stats);
> - if (vb->stats_vq->vq_ops->add_buf(vb->stats_vq, &sg, 1, 0, vb) < 0)
> + if (vb->stats_vq->vq_ops->add_buf(vb->stats_vq,
> + &sg, 1, 0, vb) < 0)
> BUG();
> vb->stats_vq->vq_ops->kick(vb->stats_vq);
> }
> diff --git a/include/linux/virtio_balloon.h b/include/linux/virtio_balloon.h
> --- a/include/linux/virtio_balloon.h
> +++ b/include/linux/virtio_balloon.h
> @@ -28,8 +28,7 @@ struct virtio_balloon_config
> #define VIRTIO_BALLOON_S_MEMTOT 5 /* Total amount of memory */
> #define VIRTIO_BALLOON_S_NR 6
>
> -struct virtio_balloon_stat
> -{
> +struct virtio_balloon_stat {
> u16 tag;
> u64 val;
> } __attribute__((packed));
>
>
--
Thanks,
Adam
On 11/30/2009 06:14 PM, Adam Litke wrote:
> Changes since V3:
> - Do not do endian conversions as they will be done in the host
> - Report stats that reference a quantity of memory in bytes
> - Minor coding style updates
>
> Changes since V2:
> - Increase stat field size to 64 bits
> - Report all sizes in kb (not pages)
> - Drop anon_pages stat and fix endianness conversion
>
> Changes since V1:
> - Use a virtqueue instead of the device config space
>
> 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.
>
> This patch enables the guest-side support by adding stats collection and
> reporting to the virtio balloon driver.
>
>
What about a spec update? Did that happen and I just missed it?
--
error compiling committee.c: too many arguments to function
On Tue, 2009-12-01 at 16:56 +0200, Avi Kivity wrote:
> What about a spec update? Did that happen and I just missed it?
Yes it did. I forgot to update this patch leader note with the link:
http://ozlabs.org/~rusty/virtio-spec/virtio-spec-0.8.2.pdf
--
Thanks,
Adam
On 12/01/2009 05:05 PM, Adam Litke wrote:
> On Tue, 2009-12-01 at 16:56 +0200, Avi Kivity wrote:
>
>> What about a spec update? Did that happen and I just missed it?
>>
> Yes it did. I forgot to update this patch leader note with the link:
> http://ozlabs.org/~rusty/virtio-spec/virtio-spec-0.8.2.pdf
>
Great, thanks.
--
error compiling committee.c: too many arguments to function