linux-kernel - Re: [PATCH v2 00/29] virtio-mem: Big Block Mode (BBM)

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Date:   Wed, 18 Nov 2020 04:00:53 -0500
From:   "Michael S. Tsirkin" <mst@...hat.com>
To:     David Hildenbrand <david@...hat.com>
Cc:     linux-kernel@...r.kernel.org,
        virtualization@...ts.linux-foundation.org, linux-mm@...ck.org,
        Andrew Morton <akpm@...ux-foundation.org>,
        Jason Wang <jasowang@...hat.com>,
        Michal Hocko <mhocko@...nel.org>,
        Oscar Salvador <osalvador@...e.de>,
        Pankaj Gupta <pankaj.gupta.linux@...il.com>,
        Wei Yang <richard.weiyang@...ux.alibaba.com>
Subject: Re: [PATCH v2 00/29] virtio-mem: Big Block Mode (BBM)

On Thu, Nov 12, 2020 at 02:37:46PM +0100, David Hildenbrand wrote:
> @Andrew, can we have an ack for patch #27, so that one can go via
> the vhost tree for 5.11?

OK, we got an ack, I'll put it in next now.
Thanks!

> ---
> 
> 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.
> 
> Patch #1 - #10 are cleanups and optimizations
> Patch #11 - #24 are refactorings to prepare for BBM
> Patch #25 - #29 implement BBM, including one mm/memory_hotplug extension
> 
> This series is based on latest linus/master and can be found at:
>  git@...hub.com:davidhildenbrand/linux.git virtio-mem-bbm-v2
> 
> v1 -> v2:
> - Code wise, the only bigger change is using an union for sbm/bbm state
> - Reworked some subjects/patch descriptions
> - Reshuffled patches to make reviweing easier, and to have
>   cleanups+optimizations before all refactorings
> - "virtio-mem: more precise calculation in
>    virtio_mem_mb_state_prepare_next_mb()"
> -- Changed subject
> -- Avoid two local variables
> 
> David Hildenbrand (29):
>   virtio-mem: determine nid only once using memory_add_physaddr_to_nid()
>   virtio-mem: more precise 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: use "unsigned long" for nr_pages when fake
>     onlining/offlining
>   virtio-mem: factor out calculation of the bit number within the
>     subblock bitmap
>   virtio-mem: print debug messages from virtio_mem_send_*_request()
>   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
>   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
>   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: nb_sb_per_mb and subblock_size are specific to Sub Block
>     Mode (SBM)
>   virtio-mem: memory block ids are specific to Sub Block Mode (SBM)
>   virito-mem: existing (un)plug functions are specific to Sub Block Mode
>     (SBM)
>   virtio-mem: memory notifier callbacks are specific to Sub Block Mode
>     (SBM)
>   virtio-mem: factor out adding/removing memory from Linux
>   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 | 1789 +++++++++++++++++++++++++----------
>  mm/memory_hotplug.c         |  105 +-
>  2 files changed, 1376 insertions(+), 518 deletions(-)
> 
> -- 
> 2.26.2