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Re: [PATCH v2 0/6] migration/postcopy: Sync faulted addresses after netw
From: |
Dr. David Alan Gilbert |
Subject: |
Re: [PATCH v2 0/6] migration/postcopy: Sync faulted addresses after network recovered |
Date: |
Wed, 23 Sep 2020 18:43:11 +0100 |
User-agent: |
Mutt/1.14.6 (2020-07-11) |
* Peter Xu (peterx@redhat.com) wrote:
> v2:
Queued
> - add r-bs for Dave
> - add patch "migration: Properly destroy variables on incoming side" as patch
> 1
> - destroy page_request_mutex in migration_incoming_state_destroy() too [Dave]
> - use WITH_QEMU_LOCK_GUARD in two places where we can [Dave]
>
> We've seen conditional guest hangs on destination VM after postcopy recovered.
> However the hang will resolve itself after a few minutes.
>
> The problem is: after a postcopy recovery, the prioritized postcopy queue on
> the source VM is actually missing. So all the faulted threads before the
> postcopy recovery happened will keep halted until (accidentally) the page got
> copied by the background precopy migration stream.
>
> The solution is to also refresh this information after postcopy recovery. To
> achieve this, we need to maintain a list of faulted addresses on the
> destination node, so that we can resend the list when necessary. This work is
> done via patch 2-5.
>
> With that, the last thing we need to do is to send this extra information to
> source VM after recovered. Very luckily, this synchronization can be
> "emulated" by sending a bunch of page requests (although these pages have been
> sent previously!) to source VM just like when we've got a page fault. Even in
> the 1st version of the postcopy code we'll handle duplicated pages well. So
> this fix does not even need a new capability bit and it'll work smoothly on
> old
> QEMUs when we migrate from them to the new QEMUs.
>
> Please review, thanks.
>
> Peter Xu (6):
> migration: Properly destroy variables on incoming side
> migration: Rework migrate_send_rp_req_pages() function
> migration: Pass incoming state into qemu_ufd_copy_ioctl()
> migration: Introduce migrate_send_rp_message_req_pages()
> migration: Maintain postcopy faulted addresses
> migration: Sync requested pages after postcopy recovery
>
> migration/migration.c | 79 +++++++++++++++++++++++++++++++++++-----
> migration/migration.h | 23 +++++++++++-
> migration/postcopy-ram.c | 46 ++++++++++-------------
> migration/savevm.c | 57 +++++++++++++++++++++++++++++
> migration/trace-events | 3 ++
> 5 files changed, 171 insertions(+), 37 deletions(-)
>
> --
> 2.26.2
>
>
>
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK
- [PATCH v2 0/6] migration/postcopy: Sync faulted addresses after network recovered, Peter Xu, 2020/09/08
- [PATCH v2 1/6] migration: Properly destroy variables on incoming side, Peter Xu, 2020/09/08
- [PATCH v2 2/6] migration: Rework migrate_send_rp_req_pages() function, Peter Xu, 2020/09/08
- [PATCH v2 6/6] migration: Sync requested pages after postcopy recovery, Peter Xu, 2020/09/08
- [PATCH v2 5/6] migration: Maintain postcopy faulted addresses, Peter Xu, 2020/09/08
- [PATCH v2 4/6] migration: Introduce migrate_send_rp_message_req_pages(), Peter Xu, 2020/09/08
- [PATCH v2 3/6] migration: Pass incoming state into qemu_ufd_copy_ioctl(), Peter Xu, 2020/09/08
- Re: [PATCH v2 0/6] migration/postcopy: Sync faulted addresses after network recovered,
Dr. David Alan Gilbert <=