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Re: [PATCH v5 3/4] migration: support UFFD write fault processing in ram
From: |
Peter Xu |
Subject: |
Re: [PATCH v5 3/4] migration: support UFFD write fault processing in ram_save_iterate() |
Date: |
Tue, 8 Dec 2020 13:09:19 -0500 |
On Fri, Dec 04, 2020 at 12:31:02PM +0300, Andrey Gruzdev wrote:
> In this particular implementation the same single migration
> thread is responsible for both normal linear dirty page
> migration and procesing UFFD page fault events.
>
> Processing write faults includes reading UFFD file descriptor,
> finding respective RAM block and saving faulting page to
> the migration stream. After page has been saved, write protection
> can be removed. Since asynchronous version of qemu_put_buffer()
> is expected to be used to save pages, we also have to flush
> migraion stream prior to un-protecting saved memory range.
>
> Write protection is being removed for any previously protected
> memory chunk that has hit the migration stream. That's valid
> for pages from linear page scan along with write fault pages.
>
> Signed-off-by: Andrey Gruzdev <andrey.gruzdev@virtuozzo.com>
I still think the ram_save_host_page_pre/post are a bit odd; but I think it's
good enough (at least Dave/Juan didn't complain yet, so I guess it's ok).
Reviewed-by: Peter Xu <peterx@redhat.com>
Thanks,
--
Peter Xu
- [PATCH v5 0/4] migration: UFFD write-tracking migration/snapshots, Andrey Gruzdev, 2020/12/04
- [PATCH v5 3/4] migration: support UFFD write fault processing in ram_save_iterate(), Andrey Gruzdev, 2020/12/04
- Re: [PATCH v5 3/4] migration: support UFFD write fault processing in ram_save_iterate(),
Peter Xu <=
- [PATCH v5 4/4] migration: implementation of background snapshot thread, Andrey Gruzdev, 2020/12/04
- [PATCH v5 2/4] migration: introduce UFFD-WP low-level interface helpers, Andrey Gruzdev, 2020/12/04
- [PATCH v5 1/4] migration: introduce 'background-snapshot' migration capability, Andrey Gruzdev, 2020/12/04
- Re: [PATCH v5 0/4] migration: UFFD write-tracking migration/snapshots, Peter Xu, 2020/12/08