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    SubjectRe: [PATCHv4 1/8] mm: Add support for unaccepted memory
    On Wed, Apr 13, 2022 at 12:36:11PM +0200, David Hildenbrand wrote:
    > On 12.04.22 18:08, Dave Hansen wrote:
    > > On 4/12/22 01:15, David Hildenbrand wrote:
    > >
    > > The other option might be to tie this all to DEFERRED_STRUCT_PAGE_INIT.
    > > Have the rule that everything that gets a 'struct page' must be
    > > accepted. If you want to do delayed acceptance, you do it via
    > > DEFERRED_STRUCT_PAGE_INIT.
    >
    > That could also be an option, yes. At least being able to chose would be
    > good. But IIRC, DEFERRED_STRUCT_PAGE_INIT will still make the system get
    > stuck during boot and wait until everything was accepted.

    The deferred page init runs multithreaded, so guest with SMP will be stuck
    for less time.

    > I see the following variants:
    >
    > 1) Slow boot; after boot, all memory is already accepted.
    > 2) Fast boot; after boot, all memory will slowly but steadily get
    > accepted in the background. After a while, all memory is accepted and
    > can be signaled to user space.
    > 3) Fast boot; after boot, memory gets accepted on demand. This is what
    > we have in this series.
    >
    > I somehow don't quite like 3), but with deferred population in the
    > hypervisor, it might just make sense.

    IMHO, deferred population in hypervisor will be way more complex than this
    series with similar "visible" performance.

    --
    Sincerely yours,
    Mike.

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