Michael S. Tsirkin
2020-Jul-16 06:39 UTC
[RFC for qemu v4 2/2] virtio_balloon: Add dcvq to deflate continuous pages
On Thu, Jul 16, 2020 at 10:41:55AM +0800, Hui Zhu wrote:> This commit adds a vq dcvq to deflate continuous pages. > When VIRTIO_BALLOON_F_CONT_PAGES is set, try to get continuous pages > from icvq and use madvise MADV_WILLNEED with the pages. > > Signed-off-by: Hui Zhu <teawaterz at linux.alibaba.com>This is arguably something to benchmark. Does guest benefit from MADV_WILLNEED or loose performance?> --- > hw/virtio/virtio-balloon.c | 14 +++++++++----- > include/hw/virtio/virtio-balloon.h | 2 +- > 2 files changed, 10 insertions(+), 6 deletions(-) > > diff --git a/hw/virtio/virtio-balloon.c b/hw/virtio/virtio-balloon.c > index d36a5c8..165adf7 100644 > --- a/hw/virtio/virtio-balloon.c > +++ b/hw/virtio/virtio-balloon.c > @@ -138,7 +138,8 @@ static void balloon_inflate_page(VirtIOBalloon *balloon, > } > > static void balloon_deflate_page(VirtIOBalloon *balloon, > - MemoryRegion *mr, hwaddr mr_offset) > + MemoryRegion *mr, hwaddr mr_offset, > + size_t size) > { > void *addr = memory_region_get_ram_ptr(mr) + mr_offset; > ram_addr_t rb_offset; > @@ -153,10 +154,11 @@ static void balloon_deflate_page(VirtIOBalloon *balloon, > rb_page_size = qemu_ram_pagesize(rb); > > host_addr = (void *)((uintptr_t)addr & ~(rb_page_size - 1)); > + size &= ~(rb_page_size - 1); > > /* When a page is deflated, we hint the whole host page it lives > * on, since we can't do anything smaller */ > - ret = qemu_madvise(host_addr, rb_page_size, QEMU_MADV_WILLNEED); > + ret = qemu_madvise(host_addr, size, QEMU_MADV_WILLNEED); > if (ret != 0) { > warn_report("Couldn't MADV_WILLNEED on balloon deflate: %s", > strerror(errno)); > @@ -354,7 +356,7 @@ static void virtio_balloon_handle_output(VirtIODevice *vdev, VirtQueue *vq) > pa = (hwaddr) p << VIRTIO_BALLOON_PFN_SHIFT; > offset += 4; > > - if (vq == s->icvq) { > + if (vq == s->icvq || vq == s->dcvq) { > uint32_t psize_ptr; > if (iov_to_buf(elem->out_sg, elem->out_num, offset, &psize_ptr, 4) != 4) { > break; > @@ -383,8 +385,9 @@ static void virtio_balloon_handle_output(VirtIODevice *vdev, VirtQueue *vq) > balloon_inflate_page(s, section.mr, > section.offset_within_region, > psize, &pbp); > - } else if (vq == s->dvq) { > - balloon_deflate_page(s, section.mr, section.offset_within_region); > + } else if (vq == s->dvq || vq == s->dcvq) { > + balloon_deflate_page(s, section.mr, section.offset_within_region, > + psize); > } else { > g_assert_not_reached(); > } > @@ -838,6 +841,7 @@ static void virtio_balloon_device_realize(DeviceState *dev, Error **errp) > > if (virtio_has_feature(s->host_features, VIRTIO_BALLOON_F_CONT_PAGES)) { > s->icvq = virtio_add_queue(vdev, 128, virtio_balloon_handle_output); > + s->dcvq = virtio_add_queue(vdev, 128, virtio_balloon_handle_output); > } > > reset_stats(s); > diff --git a/include/hw/virtio/virtio-balloon.h b/include/hw/virtio/virtio-balloon.h > index 6a2514d..848a7fb 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, *icvq; > + VirtQueue *ivq, *dvq, *svq, *free_page_vq, *icvq, *dcvq; > uint32_t free_page_report_status; > uint32_t num_pages; > uint32_t actual; > -- > 2.7.4