Re: [PATCH v1 00/29] virtio-mem: Big Block Mode (BBM)

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

On Mon, Oct 12, 2020 at 02:52:54PM +0200, David Hildenbrand wrote:
> virtio-mem currently only supports device block sizes that span at most
> a single Linux memory block. For example, gigantic pages in the hypervisor
> result on x86-64 in a device block size of 1 GiB - when the Linux memory
> block size is 128 MiB, we cannot support such devices (we fail loading the
> driver). Of course, we want to support any device block size in any Linux
> VM.
> 
> Bigger device block sizes will become especially important once supporting
> VFIO in QEMU - each device block has to be mapped separately, and the
> maximum number of mappings for VFIO is 64k. So we usually want blocks in
> the gigabyte range when wanting to grow the VM big.

I guess it missed this Linux right? There's an mm change which did not
get an ack from mm mainatiners, so I can't merge it ...

> This series:
> - Performs some cleanups
> - Factors out existing Sub Block Mode (SBM)
> - Implements memory hot(un)plug in Big Block Mode (BBM)
> 
> I need one core-mm change, to make offline_and_remove_memory() eat bigger
> chunks.
> 
> This series is based on "next-20201009" and can be found at:
> 	git@gitlab.com:virtio-mem/linux.git virtio-mem-dbm-v1
> 
> Once some virtio-mem patches that are pending in the -mm tree are upstream
> (I guess they'll go in in 5.10), I'll resend based on Linus' tree.
> I suggest to take this (including the MM patch, acks/review please) via the
> vhost tree once time has come. In the meantime, I'll do more testing.
> 
> David Hildenbrand (29):
>   virtio-mem: determine nid only once using memory_add_physaddr_to_nid()
>   virtio-mem: simplify calculation in
>     virtio_mem_mb_state_prepare_next_mb()
>   virtio-mem: simplify MAX_ORDER - 1 / pageblock_order handling
>   virtio-mem: drop rc2 in virtio_mem_mb_plug_and_add()
>   virtio-mem: generalize check for added memory
>   virtio-mem: generalize virtio_mem_owned_mb()
>   virtio-mem: generalize virtio_mem_overlaps_range()
>   virtio-mem: drop last_mb_id
>   virtio-mem: don't always trigger the workqueue when offlining memory
>   virtio-mem: generalize handling when memory is getting onlined
>     deferred
>   virtio-mem: use "unsigned long" for nr_pages when fake
>     onlining/offlining
>   virtio-mem: factor out fake-offlining into virtio_mem_fake_offline()
>   virtio-mem: factor out handling of fake-offline pages in memory
>     notifier
>   virtio-mem: retry fake-offlining via alloc_contig_range() on
>     ZONE_MOVABLE
>   virito-mem: document Sub Block Mode (SBM)
>   virtio-mem: memory block states are specific to Sub Block Mode (SBM)
>   virito-mem: subblock states are specific to Sub Block Mode (SBM)
>   virtio-mem: factor out calculation of the bit number within the
>     sb_states bitmap
>   virito-mem: existing (un)plug functions are specific to Sub Block Mode
>     (SBM)
>   virtio-mem: nb_sb_per_mb and subblock_size are specific to Sub Block
>     Mode (SBM)
>   virtio-mem: memory notifier callbacks are specific to Sub Block Mode
>     (SBM)
>   virtio-mem: memory block ids are specific to Sub Block Mode (SBM)
>   virtio-mem: factor out adding/removing memory from Linux
>   virtio-mem: print debug messages from virtio_mem_send_*_request()
>   virtio-mem: Big Block Mode (BBM) memory hotplug
>   virtio-mem: allow to force Big Block Mode (BBM) and set the big block
>     size
>   mm/memory_hotplug: extend offline_and_remove_memory() to handle more
>     than one memory block
>   virtio-mem: Big Block Mode (BBM) - basic memory hotunplug
>   virtio-mem: Big Block Mode (BBM) - safe memory hotunplug
> 
>  drivers/virtio/virtio_mem.c | 1783 +++++++++++++++++++++++++----------
>  mm/memory_hotplug.c         |  105 ++-
>  2 files changed, 1373 insertions(+), 515 deletions(-)
> 
> -- 
> 2.26.2