Messages in this thread Patch in this message | | | Subject | Re: [RFC for QEMU] virtio-balloon: Add option thp-order to set VIRTIO_BALLOON_F_THP_ORDER | From | teawater <> | Date | Tue, 17 Mar 2020 18:13:32 +0800 |
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> 2020年3月12日 16:25,Michael S. Tsirkin <mst@redhat.com> 写道: > > On Thu, Mar 12, 2020 at 03:49:55PM +0800, Hui Zhu wrote: >> 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@linux.alibaba.com> > > What's wrong with just using the PartiallyBalloonedPage machinery > instead? That would make it guest transparent.
In balloon_inflate_page: rb_page_size = qemu_ram_pagesize(rb);
if (rb_page_size == BALLOON_PAGE_SIZE) { /* Easy case */
It seems that PartiallyBalloonedPage is only used when rb_page_size is greater than BALLOON_PAGE_SIZE. Do you mean I should modify the working mechanism of balloon_inflate_page function?
Thanks, Hui
> >> --- >> 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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