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

David Hildenbrand
2020-03-26T07:20:24Z

> Am 26.03.2020 um 08:06 schrieb teawater <teawaterz@linux.alibaba.com>:
>
> ﻿Ping.
>

On paid leave this week. Will try to have a look next week, but it could take a bit longer.

Cheers

> 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
>>
>