Re: [Qemu-devel] [PATCH v11 0/7] virtio-balloon: free page hint support

["Michael S. Tsirkin" <mst@redhat.com>]

On Tue, Dec 11, 2018 at 04:24:46PM +0800, Wei Wang wrote:
> This is the deivce part implementation to add a new feature,
> VIRTIO_BALLOON_F_FREE_PAGE_HINT to the virtio-balloon device. The device
> receives the guest free page hints from the driver and clears the
> corresponding bits in the dirty bitmap, so that those free pages are
> not sent by the migration thread to the destination.

For virtio bits:

Reviewed-by: Michael S. Tsirkin <mst@redhat.com>

I think this is primarily a migration feature so please merge
through the migration tree.



> *Tests
> 1 Test Environment
>     Host: Intel(R) Xeon(R) CPU E5-2699 v4 @ 2.20GHz
>     Migration setup: migrate_set_speed 100G, migrate_set_downtime 400ms
> 
> 2 Test Results (results are averaged over several repeated runs)
>     2.1 Guest setup: 8G RAM, 4 vCPU
>         2.1.1 Idle guest live migration time
>             Optimization v.s. Legacy = 620ms vs 2970ms
>             --> ~79% reduction
>         2.1.2 Guest live migration with Linux compilation workload
>           (i.e. make bzImage -j4) running
>           1) Live Migration Time:
>              Optimization v.s. Legacy = 2273ms v.s. 4502ms
>              --> ~50% reduction
>           2) Linux Compilation Time:
>              Optimization v.s. Legacy = 8min42s v.s. 8min43s
>              --> no obvious difference
> 
>     2.2 Guest setup: 128G RAM, 4 vCPU
>         2.2.1 Idle guest live migration time
>             Optimization v.s. Legacy = 5294ms vs 41651ms
>             --> ~87% reduction
>         2.2.2 Guest live migration with Linux compilation workload
>           1) Live Migration Time:
>             Optimization v.s. Legacy = 8816ms v.s. 54201ms
>             --> 84% reduction
>           2) Linux Compilation Time:
>             Optimization v.s. Legacy = 8min30s v.s. 8min36s
>             --> no obvious difference
> 
> ChangeLog:
> v10->v11:
> migration:
>     - qemu_guest_free_page_hint:
>         - "offset >= block->used_length", instead of
>           "offset > block->used_length";
>     - RAMState: enable the "fpo_enabled" flag, when the free page
>       optimization feature is used, instead of disabling ram_bulk_stage.
>       Please see patch 6 commit log for details.
> 
> Previous changelog:
> http://lists.nongnu.org/archive/html/qemu-devel/2018-12/msg00055.html
> 
> Wei Wang (7):
>   bitmap: fix bitmap_count_one
>   bitmap: bitmap_count_one_with_offset
>   migration: use bitmap_mutex in migration_bitmap_clear_dirty
>   migration: API to clear bits of guest free pages from the dirty bitmap
>   migration/ram.c: add a notifier chain for precopy
>   migration/ram.c: add the free page optimization enable flag
>   virtio-balloon: VIRTIO_BALLOON_F_FREE_PAGE_HINT
> 
>  hw/virtio/virtio-balloon.c                      | 263 ++++++++++++++++++++++++
>  include/hw/virtio/virtio-balloon.h              |  28 ++-
>  include/migration/misc.h                        |  22 ++
>  include/qemu/bitmap.h                           |  17 ++
>  include/standard-headers/linux/virtio_balloon.h |   5 +
>  migration/ram.c                                 | 121 ++++++++++-
>  migration/savevm.c                              |  15 ++
>  vl.c                                            |   1 +
>  8 files changed, 466 insertions(+), 6 deletions(-)
> 
> -- 
> 1.8.3.1