Re: [PATCH for QEMU v2] virtio-balloon: Add option cont-pages to set VIRTIO_BALLOON_VQ_INFLATE_CONT

teawater
2020-03-26T07:07:02Z

Ping.

Thanks,
Hui

> 2020年3月23日 00:04，Hui Zhu <teawater@gmail.com> 写道：
>
> 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 continuous pages order to THP order.
> Then It will get continuous pages PFN from VQ icvq use use madvise
> MADV_DONTNEED release the THP page.
> This will handle the THP split issue.
>
> Signed-off-by: Hui Zhu <teawaterz@linux.alibaba.com>
> ---
> hw/virtio/virtio-balloon.c | 32 +++++++++++++++++++++----
> include/hw/virtio/virtio-balloon.h | 4 +++-
> include/standard-headers/linux/virtio_balloon.h | 4 ++++
> 3 files changed, 35 insertions(+), 5 deletions(-)
>
> diff --git a/hw/virtio/virtio-balloon.c b/hw/virtio/virtio-balloon.c
> index a4729f7..88bdaca 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;
> @@ -65,7 +66,8 @@ static bool virtio_balloon_pbp_matches(PartiallyBalloonedPage *pbp,
>
> static void balloon_inflate_page(VirtIOBalloon *balloon,
> MemoryRegion *mr, hwaddr mr_offset,
> - PartiallyBalloonedPage *pbp)
> + PartiallyBalloonedPage *pbp,
> + bool is_cont_pages)
> {
> void *addr = memory_region_get_ram_ptr(mr) + mr_offset;
> ram_addr_t rb_offset, rb_aligned_offset, base_gpa;
> @@ -76,6 +78,13 @@ static void balloon_inflate_page(VirtIOBalloon *balloon,
> /* XXX is there a better way to get to the RAMBlock than via a
> * host address? */
> rb = qemu_ram_block_from_host(addr, false, &rb_offset);
> +
> + if (is_cont_pages) {
> + ram_block_discard_range(rb, rb_offset,
> + BALLOON_PAGE_SIZE << CONT_PAGES_ORDER);
> + return;
> + }
> +
> rb_page_size = qemu_ram_pagesize(rb);
>
> if (rb_page_size == BALLOON_PAGE_SIZE) {
> @@ -361,9 +370,10 @@ static void virtio_balloon_handle_output(VirtIODevice *vdev, VirtQueue *vq)
> trace_virtio_balloon_handle_output(memory_region_name(section.mr),
> pa);
> if (!qemu_balloon_is_inhibited()) {
> - if (vq == s->ivq) {
> + if (vq == s->ivq || vq == s->icvq) {
> balloon_inflate_page(s, section.mr,
> - section.offset_within_region, &pbp);
> + section.offset_within_region, &pbp,
> + vq == s->icvq);
> } else if (vq == s->dvq) {
> balloon_deflate_page(s, section.mr, section.offset_within_region);
> } else {
> @@ -618,9 +628,12 @@ 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, pages_order);
> + }
> if (virtio_has_feature(features, VIRTIO_BALLOON_F_FREE_PAGE_HINT)) {
> return offsetof(struct virtio_balloon_config, poison_val);
> }
> @@ -646,6 +659,10 @@ 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.pages_order = cpu_to_le32(CONT_PAGES_ORDER);
> + }
> +
> trace_virtio_balloon_get_config(config.num_pages, config.actual);
> memcpy(config_data, &config, virtio_balloon_config_size(dev));
> }
> @@ -816,6 +833,11 @@ 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->icvq = virtio_add_queue(vdev, 128, virtio_balloon_handle_output);
> + }
> +
> reset_stats(s);
> }
>
> @@ -916,6 +938,8 @@ 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..61d2419 100644
> --- a/include/hw/virtio/virtio-balloon.h
> +++ b/include/hw/virtio/virtio-balloon.h
> @@ -42,7 +42,7 @@ enum virtio_balloon_free_page_report_status {
>
> typedef struct VirtIOBalloon {
> VirtIODevice parent_obj;
> - VirtQueue *ivq, *dvq, *svq, *free_page_vq;
> + VirtQueue *ivq, *dvq, *svq, *free_page_vq, *icvq;
> uint32_t free_page_report_status;
> uint32_t num_pages;
> uint32_t actual;
> @@ -70,6 +70,8 @@ typedef struct VirtIOBalloon {
> uint32_t host_features;
>
> bool qemu_4_0_config_size;
> +
> + uint32_t pages_order;
> } VirtIOBalloon;
>
> #endif
> diff --git a/include/standard-headers/linux/virtio_balloon.h b/include/standard-headers/linux/virtio_balloon.h
> index 9375ca2..ee18be7 100644
> --- a/include/standard-headers/linux/virtio_balloon.h
> +++ b/include/standard-headers/linux/virtio_balloon.h
> @@ -36,6 +36,8 @@
> #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 5 /* VQ to report continuous pages */
> +
>
> /* Size of a PFN in the balloon interface. */
> #define VIRTIO_BALLOON_PFN_SHIFT 12
> @@ -51,6 +53,8 @@ struct virtio_balloon_config {
> uint32_t free_page_report_cmd_id;
> /* Stores PAGE_POISON if page poisoning is in use */
> uint32_t poison_val;
> + /* Pages order if VIRTIO_BALLOON_F_CONT_PAGES is set */
> + uint32_t pages_order;
> };
>
> #define VIRTIO_BALLOON_S_SWAP_IN 0 /* Amount of memory swapped in */
> --
> 2.7.4
>