[RFC v3 for QEMU] virtio-balloon: Add option cont-pages to set VIRTIO_BALLOON_VQ_INFLATE_CONT
From: Hui Zhu
Date: Tue May 12 2020 - 05:42:04 EST
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 cont-pages to on will open flags VIRTIO_BALLOON_VQ_INFLATE_CONT
and set default continuous pages order to THP order.
Then It will get continuous pages PFN that its order is current_pages_order
from VQ ivq use use madvise MADV_DONTNEED release the page.
This will handle the THP split issue.
Signed-off-by: Hui Zhu <teawaterz@xxxxxxxxxxxxxxxxx>
---
hw/virtio/virtio-balloon.c | 77 +++++++++++++++++--------
include/hw/virtio/virtio-balloon.h | 2 +
include/standard-headers/linux/virtio_balloon.h | 5 ++
3 files changed, 60 insertions(+), 24 deletions(-)
diff --git a/hw/virtio/virtio-balloon.c b/hw/virtio/virtio-balloon.c
index a4729f7..84d47d3 100644
--- a/hw/virtio/virtio-balloon.c
+++ b/hw/virtio/virtio-balloon.c
@@ -34,6 +34,7 @@
#include "hw/virtio/virtio-access.h"
#define BALLOON_PAGE_SIZE (1 << VIRTIO_BALLOON_PFN_SHIFT)
+#define CONT_PAGES_ORDER 9
typedef struct PartiallyBalloonedPage {
ram_addr_t base_gpa;
@@ -72,6 +73,8 @@ static void balloon_inflate_page(VirtIOBalloon *balloon,
RAMBlock *rb;
size_t rb_page_size;
int subpages;
+ size_t inflate_size = BALLOON_PAGE_SIZE << balloon->current_pages_order;
+ int pages_num;
/* XXX is there a better way to get to the RAMBlock than via a
* host address? */
@@ -81,7 +84,7 @@ static void balloon_inflate_page(VirtIOBalloon *balloon,
if (rb_page_size == BALLOON_PAGE_SIZE) {
/* Easy case */
- ram_block_discard_range(rb, rb_offset, rb_page_size);
+ ram_block_discard_range(rb, rb_offset, inflate_size);
/* We ignore errors from ram_block_discard_range(), because it
* has already reported them, and failing to discard a balloon
* page is not fatal */
@@ -99,32 +102,38 @@ static void balloon_inflate_page(VirtIOBalloon *balloon,
rb_aligned_offset = QEMU_ALIGN_DOWN(rb_offset, rb_page_size);
subpages = rb_page_size / BALLOON_PAGE_SIZE;
- base_gpa = memory_region_get_ram_addr(mr) + mr_offset -
- (rb_offset - rb_aligned_offset);
- if (pbp->bitmap && !virtio_balloon_pbp_matches(pbp, base_gpa)) {
- /* We've partially ballooned part of a host page, but now
- * we're trying to balloon part of a different one. Too hard,
- * give up on the old partial page */
- virtio_balloon_pbp_free(pbp);
- }
+ for (pages_num = inflate_size / BALLOON_PAGE_SIZE;
+ pages_num > 0; pages_num--) {
+ base_gpa = memory_region_get_ram_addr(mr) + mr_offset -
+ (rb_offset - rb_aligned_offset);
- if (!pbp->bitmap) {
- virtio_balloon_pbp_alloc(pbp, base_gpa, subpages);
- }
+ if (pbp->bitmap && !virtio_balloon_pbp_matches(pbp, base_gpa)) {
+ /* We've partially ballooned part of a host page, but now
+ * we're trying to balloon part of a different one. Too hard,
+ * give up on the old partial page */
+ virtio_balloon_pbp_free(pbp);
+ }
- set_bit((rb_offset - rb_aligned_offset) / BALLOON_PAGE_SIZE,
- pbp->bitmap);
+ if (!pbp->bitmap) {
+ virtio_balloon_pbp_alloc(pbp, base_gpa, subpages);
+ }
- if (bitmap_full(pbp->bitmap, subpages)) {
- /* We've accumulated a full host page, we can actually discard
- * it now */
+ set_bit((rb_offset - rb_aligned_offset) / BALLOON_PAGE_SIZE,
+ pbp->bitmap);
- ram_block_discard_range(rb, rb_aligned_offset, rb_page_size);
- /* We ignore errors from ram_block_discard_range(), because it
- * has already reported them, and failing to discard a balloon
- * page is not fatal */
- virtio_balloon_pbp_free(pbp);
+ if (bitmap_full(pbp->bitmap, subpages)) {
+ /* We've accumulated a full host page, we can actually discard
+ * it now */
+
+ ram_block_discard_range(rb, rb_aligned_offset, rb_page_size);
+ /* We ignore errors from ram_block_discard_range(), because it
+ * has already reported them, and failing to discard a balloon
+ * page is not fatal */
+ virtio_balloon_pbp_free(pbp);
+ }
+
+ mr_offset += BALLOON_PAGE_SIZE;
}
}
@@ -345,7 +354,7 @@ static void virtio_balloon_handle_output(VirtIODevice *vdev, VirtQueue *vq)
offset += 4;
section = memory_region_find(get_system_memory(), pa,
- BALLOON_PAGE_SIZE);
+ BALLOON_PAGE_SIZE << s->current_pages_order);
if (!section.mr) {
trace_virtio_balloon_bad_addr(pa);
continue;
@@ -618,9 +627,12 @@ static size_t virtio_balloon_config_size(VirtIOBalloon *s)
if (s->qemu_4_0_config_size) {
return sizeof(struct virtio_balloon_config);
}
- if (virtio_has_feature(features, VIRTIO_BALLOON_F_PAGE_POISON)) {
+ if (virtio_has_feature(s->host_features, VIRTIO_BALLOON_F_CONT_PAGES)) {
return sizeof(struct virtio_balloon_config);
}
+ if (virtio_has_feature(features, VIRTIO_BALLOON_F_PAGE_POISON)) {
+ return offsetof(struct virtio_balloon_config, current_pages_order);
+ }
if (virtio_has_feature(features, VIRTIO_BALLOON_F_FREE_PAGE_HINT)) {
return offsetof(struct virtio_balloon_config, poison_val);
}
@@ -646,6 +658,11 @@ static void virtio_balloon_get_config(VirtIODevice *vdev, uint8_t *config_data)
cpu_to_le32(VIRTIO_BALLOON_CMD_ID_DONE);
}
+ if (virtio_has_feature(dev->host_features, VIRTIO_BALLOON_F_CONT_PAGES)) {
+ config.max_pages_order = cpu_to_le32(CONT_PAGES_ORDER);
+ config.current_pages_order = cpu_to_le32(dev->current_pages_order);
+ }
+
trace_virtio_balloon_get_config(config.num_pages, config.actual);
memcpy(config_data, &config, virtio_balloon_config_size(dev));
}
@@ -693,6 +710,9 @@ 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(dev->host_features, VIRTIO_BALLOON_F_CONT_PAGES)) {
+ dev->current_pages_order = le32_to_cpu(config.current_pages_order);
+ }
if (dev->actual != oldactual) {
qapi_event_send_balloon_change(vm_ram_size -
((ram_addr_t) dev->actual << VIRTIO_BALLOON_PFN_SHIFT));
@@ -816,6 +836,13 @@ static void virtio_balloon_device_realize(DeviceState *dev, Error **errp)
virtio_error(vdev, "iothread is missing");
}
}
+
+ if (virtio_has_feature(s->host_features, VIRTIO_BALLOON_F_CONT_PAGES)) {
+ s->current_pages_order = CONT_PAGES_ORDER;
+ } else {
+ s->current_pages_order = 0;
+ }
+
reset_stats(s);
}
@@ -916,6 +943,8 @@ 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("cont-pages", VirtIOBalloon, host_features,
+ VIRTIO_BALLOON_F_CONT_PAGES, 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/hw/virtio/virtio-balloon.h b/include/hw/virtio/virtio-balloon.h
index d1c968d..e0dce0d 100644
--- a/include/hw/virtio/virtio-balloon.h
+++ b/include/hw/virtio/virtio-balloon.h
@@ -70,6 +70,8 @@ typedef struct VirtIOBalloon {
uint32_t host_features;
bool qemu_4_0_config_size;
+
+ uint32_t current_pages_order;
} VirtIOBalloon;
#endif
diff --git a/include/standard-headers/linux/virtio_balloon.h b/include/standard-headers/linux/virtio_balloon.h
index 9375ca2..b5386ce 100644
--- a/include/standard-headers/linux/virtio_balloon.h
+++ b/include/standard-headers/linux/virtio_balloon.h
@@ -36,6 +36,7 @@
#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_CONT_PAGES 6 /* VQ to report continuous pages */
/* Size of a PFN in the balloon interface. */
#define VIRTIO_BALLOON_PFN_SHIFT 12
@@ -51,6 +52,10 @@ struct virtio_balloon_config {
uint32_t free_page_report_cmd_id;
/* Stores PAGE_POISON if page poisoning is in use */
uint32_t poison_val;
+ /* Max pages order if VIRTIO_BALLOON_F_CONT_PAGES is set */
+ uint32_t max_pages_order;
+ /* Current pages order if VIRTIO_BALLOON_F_CONT_PAGES is set */
+ uint32_t current_pages_order;
};
#define VIRTIO_BALLOON_S_SWAP_IN 0 /* Amount of memory swapped in */
--
1.8.3.1