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Date: Thu, 12 Mar 2020 15:49:55 +0800
From: Hui Zhu <teawater@...il.com>
To: mst@...hat.com, jasowang@...hat.com, akpm@...ux-foundation.org,
pagupta@...hat.com, mojha@...eaurora.org, david@...hat.com,
namit@...are.com, virtualization@...ts.linux-foundation.org,
linux-kernel@...r.kernel.org, qemu-devel@...gnu.org
Cc: Hui Zhu <teawater@...il.com>, Hui Zhu <teawaterz@...ux.alibaba.com>
Subject: [RFC for QEMU] virtio-balloon: Add option thp-order to set VIRTIO_BALLOON_F_THP_ORDER
If the guest kernel has many fragmentation pages, use virtio_balloon
will split THP of QEMU when it calls MADV_DONTNEED madvise to release
the balloon pages.
Set option thp-order to on will open flags VIRTIO_BALLOON_F_THP_ORDER.
It will set balloon size to THP size to handle the THP split issue.
Signed-off-by: Hui Zhu <teawaterz@...ux.alibaba.com>
---
hw/virtio/virtio-balloon.c | 67 ++++++++++++++++---------
include/standard-headers/linux/virtio_balloon.h | 4 ++
2 files changed, 47 insertions(+), 24 deletions(-)
diff --git a/hw/virtio/virtio-balloon.c b/hw/virtio/virtio-balloon.c
index a4729f7..cfe86b0 100644
--- a/hw/virtio/virtio-balloon.c
+++ b/hw/virtio/virtio-balloon.c
@@ -340,37 +340,49 @@ static void virtio_balloon_handle_output(VirtIODevice *vdev, VirtQueue *vq)
while (iov_to_buf(elem->out_sg, elem->out_num, offset, &pfn, 4) == 4) {
unsigned int p = virtio_ldl_p(vdev, &pfn);
hwaddr pa;
+ size_t handle_size = BALLOON_PAGE_SIZE;
pa = (hwaddr) p << VIRTIO_BALLOON_PFN_SHIFT;
offset += 4;
- section = memory_region_find(get_system_memory(), pa,
- BALLOON_PAGE_SIZE);
- if (!section.mr) {
- trace_virtio_balloon_bad_addr(pa);
- continue;
- }
- if (!memory_region_is_ram(section.mr) ||
- memory_region_is_rom(section.mr) ||
- memory_region_is_romd(section.mr)) {
- trace_virtio_balloon_bad_addr(pa);
- memory_region_unref(section.mr);
- continue;
- }
+ if (virtio_has_feature(s->host_features,
+ VIRTIO_BALLOON_F_THP_ORDER))
+ handle_size = BALLOON_PAGE_SIZE << VIRTIO_BALLOON_THP_ORDER;
+
+ while (handle_size > 0) {
+ section = memory_region_find(get_system_memory(), pa,
+ BALLOON_PAGE_SIZE);
+ if (!section.mr) {
+ trace_virtio_balloon_bad_addr(pa);
+ continue;
+ }
+ if (!memory_region_is_ram(section.mr) ||
+ memory_region_is_rom(section.mr) ||
+ memory_region_is_romd(section.mr)) {
+ trace_virtio_balloon_bad_addr(pa);
+ memory_region_unref(section.mr);
+ continue;
+ }
- trace_virtio_balloon_handle_output(memory_region_name(section.mr),
- pa);
- if (!qemu_balloon_is_inhibited()) {
- if (vq == s->ivq) {
- balloon_inflate_page(s, section.mr,
- section.offset_within_region, &pbp);
- } else if (vq == s->dvq) {
- balloon_deflate_page(s, section.mr, section.offset_within_region);
- } else {
- g_assert_not_reached();
+ trace_virtio_balloon_handle_output(memory_region_name(section.mr),
+ pa);
+ if (!qemu_balloon_is_inhibited()) {
+ if (vq == s->ivq) {
+ balloon_inflate_page(s, section.mr,
+ section.offset_within_region,
+ &pbp);
+ } else if (vq == s->dvq) {
+ balloon_deflate_page(s, section.mr,
+ section.offset_within_region);
+ } else {
+ g_assert_not_reached();
+ }
}
+ memory_region_unref(section.mr);
+
+ pa += BALLOON_PAGE_SIZE;
+ handle_size -= BALLOON_PAGE_SIZE;
}
- memory_region_unref(section.mr);
}
virtqueue_push(vq, elem, offset);
@@ -693,6 +705,8 @@ static void virtio_balloon_set_config(VirtIODevice *vdev,
memcpy(&config, config_data, virtio_balloon_config_size(dev));
dev->actual = le32_to_cpu(config.actual);
+ if (virtio_has_feature(vdev->host_features, VIRTIO_BALLOON_F_THP_ORDER))
+ dev->actual <<= VIRTIO_BALLOON_THP_ORDER;
if (dev->actual != oldactual) {
qapi_event_send_balloon_change(vm_ram_size -
((ram_addr_t) dev->actual << VIRTIO_BALLOON_PFN_SHIFT));
@@ -728,6 +742,9 @@ static void virtio_balloon_to_target(void *opaque, ram_addr_t target)
}
if (target) {
dev->num_pages = (vm_ram_size - target) >> VIRTIO_BALLOON_PFN_SHIFT;
+ if (virtio_has_feature(dev->host_features,
+ VIRTIO_BALLOON_F_THP_ORDER))
+ dev->num_pages >>= VIRTIO_BALLOON_THP_ORDER;
virtio_notify_config(vdev);
}
trace_virtio_balloon_to_target(target, dev->num_pages);
@@ -916,6 +933,8 @@ static Property virtio_balloon_properties[] = {
VIRTIO_BALLOON_F_DEFLATE_ON_OOM, false),
DEFINE_PROP_BIT("free-page-hint", VirtIOBalloon, host_features,
VIRTIO_BALLOON_F_FREE_PAGE_HINT, false),
+ DEFINE_PROP_BIT("thp-order", VirtIOBalloon, host_features,
+ VIRTIO_BALLOON_F_THP_ORDER, false),
/* QEMU 4.0 accidentally changed the config size even when free-page-hint
* is disabled, resulting in QEMU 3.1 migration incompatibility. This
* property retains this quirk for QEMU 4.1 machine types.
diff --git a/include/standard-headers/linux/virtio_balloon.h b/include/standard-headers/linux/virtio_balloon.h
index 9375ca2..f54d613 100644
--- a/include/standard-headers/linux/virtio_balloon.h
+++ b/include/standard-headers/linux/virtio_balloon.h
@@ -36,10 +36,14 @@
#define VIRTIO_BALLOON_F_DEFLATE_ON_OOM 2 /* Deflate balloon on OOM */
#define VIRTIO_BALLOON_F_FREE_PAGE_HINT 3 /* VQ to report free pages */
#define VIRTIO_BALLOON_F_PAGE_POISON 4 /* Guest is using page poisoning */
+#define VIRTIO_BALLOON_F_THP_ORDER 5 /* Set balloon page order to thp order */
/* Size of a PFN in the balloon interface. */
#define VIRTIO_BALLOON_PFN_SHIFT 12
+/* The order of the balloon page */
+#define VIRTIO_BALLOON_THP_ORDER 9
+
#define VIRTIO_BALLOON_CMD_ID_STOP 0
#define VIRTIO_BALLOON_CMD_ID_DONE 1
struct virtio_balloon_config {
--
2.7.4
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