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Re: [Qemu-devel] [PATCH v4 00/47] Postcopy implementation
From: |
Dr. David Alan Gilbert |
Subject: |
Re: [Qemu-devel] [PATCH v4 00/47] Postcopy implementation |
Date: |
Tue, 7 Oct 2014 09:12:49 +0100 |
User-agent: |
Mutt/1.5.23 (2014-03-12) |
* Cristian Klein (address@hidden) wrote:
> On 04 Oct 2014, at 4:21 , Dr. David Alan Gilbert <address@hidden> wrote:
>
> >
> > I've updated our github at:
> > https://github.com/orbitfp7/qemu/tree/wp3-postcopy
> >
> > to have this version.
> >
> > and it corresponds to the tag:
> > https://github.com/orbitfp7/qemu/releases/tag/wp3-postcopy-v4
>
> Hi Dave,
>
> I just tested this version of post-copy using the libvirt patches I recently
> posted and it works a lot better. The video streaming VM migrates with a
> downtime of less than 1 second. Before post-copy finishes, the VM is a bit
> slow but otherwise running well.
>
> I also tested the patches with a VM doing ?ping? and the downtime was around
> 0.6 seconds. I suspect that this delay could be caused by libvirt and not by
> qemu. Notice that, libvirt is a bit special, in the sense that the VM is
> migrated in suspended state and resumed only after the network was set up on
> the destination. I will investigate and let you know.
That's great news - although I'm not quite sure what caused the improvement,
there
were quite a few minor bug fixes and things but nothing that I can think of that
would directly contribute (except the patches I'd sent you which you'd already
tried).
Dave
>
> Cristian
>
> > * Dr. David Alan Gilbert (git) (address@hidden) wrote:
> >> From: "Dr. David Alan Gilbert" <address@hidden>
> >>
> >> Hi,
> >> This is the 4th cut of my version of postcopy; it is designed for use with
> >> the Linux kernel additions just posted by Andrea Arcangeli here:
> >>
> >> http://marc.info/?l=linux-kernel&m=141235633015100&w=2
> >>
> >> (Note: This is a new version compared to my previous postcopy patchset;
> >> you'll
> >> need to update the kernel to the new version.)
> >>
> >> Other than the new kernel ABI (which is only a small change to the
> >> userspace side);
> >> the major changes are;
> >>
> >> a) Code for host page size != target page size
> >> b) Support for migration over fd
> >> From Cristian Klein; this is for libvirt support which Cristian
> >> recently
> >> posted to the libvirt list.
> >> c) It's now build bisectable and builds on 32bit
> >>
> >> Testing wise; I've now done many thousand of postcopy migrations without
> >> failure (both of idle and busy guests); so it seems pretty solid.
> >>
> >> Must-TODO's:
> >> 1) A partially repeatable migration_cancel failure
> >> 2) virt_test's migrate.with_reboot test is failing
> >> 3) The ACPI fix in 2.1 that allowed migrating RAMBlocks to be larger than
> >> the source feels like it needs looking at for postcopy.
> >> 4) Paolo's comments with respect to the wakeup_request/is_running code
> >> in the migration thread
> >> 5) xbzrle needs disabling once in postcopy
> >>
> >> Later-TODO's:
> >> 1) Control the rate of background page transfers during postcopy to
> >> reduce their impact on the latency of postcopy requests.
> >> 2) Work with RDMA
> >> 3) Could destination RP be made blocking (as per discussion with Paolo;
> >> I'm still worried that that changes too many assumptions)
> >>
> >>
> >>
> >> V4:
> >> Initial support for host page size != target page size
> >> - tested heavily on hps==tps
> >> - only partially tested on hps!=tps systems
> >> - This involved quite a bit of rework around the discard code
> >> Updated to new kernel userfault ABI
> >> - It won't work with the previous version
> >> Fix mis-optimisation of postcopy request for wrong RAMBlock
> >> request for block A offset n
> >> un-needed fault for block B/m (already received - no req sent)
> >> request for block B/l - wrongly sent as request for A/l
> >> Fix thinko in discard bitmap processing (missed last word of bitmap)
> >> Symptom: remap failures near the top of RAM if postcopy started late
> >> Fix bug that caused kernel page acknowledgments to be misaligned
> >> May have meant the guest was paused for longer than required
> >> Fix potential for crashing cleaning up failed RP
> >> Fixes in docs (from Yang)
> >> Handle migration by fd as sockets if they are sockets
> >> Build tested on 32bit
> >> Fully build bisectable (x86-64)
> >>
> >>
> >> Dave
> >>
> >> Cristian Klein (1):
> >> Handle bi-directional communication for fd migration
> >>
> >> Dr. David Alan Gilbert (46):
> >> QEMUSizedBuffer based QEMUFile
> >> Tests: QEMUSizedBuffer/QEMUBuffer
> >> Start documenting how postcopy works.
> >> qemu_ram_foreach_block: pass up error value, and down the ramblock
> >> name
> >> improve DPRINTF macros, add to savevm
> >> Add qemu_get_counted_string to read a string prefixed by a count byte
> >> Create MigrationIncomingState
> >> socket shutdown
> >> Provide runtime Target page information
> >> Return path: Open a return path on QEMUFile for sockets
> >> Return path: socket_writev_buffer: Block even on non-blocking fd's
> >> Migration commands
> >> Return path: Control commands
> >> Return path: Send responses from destination to source
> >> Return path: Source handling of return path
> >> qemu_loadvm errors and debug
> >> ram_debug_dump_bitmap: Dump a migration bitmap as text
> >> Rework loadvm path for subloops
> >> Add migration-capability boolean for postcopy-ram.
> >> Add wrappers and handlers for sending/receiving the postcopy-ram
> >> migration messages.
> >> QEMU_VM_CMD_PACKAGED: Send a packaged chunk of migration stream
> >> migrate_init: Call from savevm
> >> Allow savevm handlers to state whether they could go into postcopy
> >> postcopy: OS support test
> >> migrate_start_postcopy: Command to trigger transition to postcopy
> >> MIG_STATE_POSTCOPY_ACTIVE: Add new migration state
> >> qemu_savevm_state_complete: Postcopy changes
> >> Postcopy page-map-incoming (PMI) structure
> >> Postcopy: Maintain sentmap and calculate discard
> >> postcopy: Incoming initialisation
> >> postcopy: ram_enable_notify to switch on userfault
> >> Postcopy: Postcopy startup in migration thread
> >> Postcopy: Create a fault handler thread before marking the ram as
> >> userfault
> >> Page request: Add MIG_RPCOMM_REQPAGES reverse command
> >> Page request: Process incoming page request
> >> Page request: Consume pages off the post-copy queue
> >> Add assertion to check migration_dirty_pages
> >> postcopy_ram.c: place_page and helpers
> >> Postcopy: Use helpers to map pages during migration
> >> qemu_ram_block_from_host
> >> Don't sync dirty bitmaps in postcopy
> >> Host page!=target page: Cleanup bitmaps
> >> Postcopy; Handle userfault requests
> >> Start up a postcopy/listener thread ready for incoming page data
> >> postcopy: Wire up loadvm_postcopy_ram_handle_{run,end} commands
> >> End of migration for postcopy
> >>
> >> Makefile.objs | 2 +-
> >> arch_init.c | 739 +++++++++++++++++++++++++--
> >> docs/migration.txt | 189 +++++++
> >> exec.c | 76 ++-
> >> hmp-commands.hx | 15 +
> >> hmp.c | 7 +
> >> hmp.h | 1 +
> >> include/exec/cpu-common.h | 8 +-
> >> include/migration/migration.h | 130 +++++
> >> include/migration/postcopy-ram.h | 106 ++++
> >> include/migration/qemu-file.h | 47 ++
> >> include/migration/vmstate.h | 2 +-
> >> include/qemu/sockets.h | 1 +
> >> include/qemu/typedefs.h | 9 +-
> >> include/sysemu/sysemu.h | 43 +-
> >> migration-fd.c | 24 +-
> >> migration-rdma.c | 4 +-
> >> migration.c | 693 +++++++++++++++++++++++++-
> >> postcopy-ram.c | 1016
> >> ++++++++++++++++++++++++++++++++++++++
> >> qapi-schema.json | 14 +-
> >> qemu-file.c | 598 +++++++++++++++++++++-
> >> qmp-commands.hx | 19 +
> >> savevm.c | 881 +++++++++++++++++++++++++++++++--
> >> tests/Makefile | 2 +-
> >> tests/test-vmstate.c | 74 +--
> >> util/qemu-sockets.c | 28 ++
> >> 26 files changed, 4550 insertions(+), 178 deletions(-)
> >> create mode 100644 include/migration/postcopy-ram.h
> >> create mode 100644 postcopy-ram.c
> >>
> >> --
> >> 1.9.3
> >>
> >>
> > --
> > Dr. David Alan Gilbert / address@hidden / Manchester, UK
>
--
Dr. David Alan Gilbert / address@hidden / Manchester, UK