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Re: [Qemu-devel] [PATCH v5 00/12] rdma: migration support


From: Michael R. Hines
Subject: Re: [Qemu-devel] [PATCH v5 00/12] rdma: migration support
Date: Tue, 23 Apr 2013 13:54:35 -0400
User-agent: Mozilla/5.0 (X11; Linux i686; rv:17.0) Gecko/20130106 Thunderbird/17.0.2

On 04/23/2013 01:50 PM, Anthony Liguori wrote:
address@hidden writes:

From: "Michael R. Hines" <address@hidden>

Juan, Please pull.
I assume this is actually v6, not v5?

I don't see collected Reviewed-bys...

That said, we're pretty close to hard freeze.  I think this should wait
until 1.6 opens up although I'm open to suggestion if people think this
is low risk.  I don't like the idea of adding a new protocol this close
to the end of a cycle.

Regards,

Anthony Liguori

There are no instructions/procedures documented on the qemu.org
website on how to automatically generate "Reviewed-by" signatures.

How do you guys do that?

- Michael

Changes since v4:

- Re-ran checkpatch.pl
- Added new QEMUFileOps function: qemu_get_max_size()
- Renamed capability to x-pin-all, disabled by default
- Added numbers for x-pin-all to performance section in docs/rdma.txt
- Included performance numbers in this cover letter
- Converted throughput patch to a MigrationStats statistic in QMP
- Better QMP error message delivery
- Updated documentation
- Moved docs/rdma.txt up to top of patch series
- Fixed all v4 changes requested
- Finished additional cleanup requests
- Updated copyright for migration-rdma.c

Wiki: http://wiki.qemu.org/Features/RDMALiveMigration
Github: address@hidden:hinesmr/qemu.git

Here is a brief summary of total migration time and downtime using RDMA:

Using a 40gbps infiniband link performing a worst-case stress test,
using an 8GB RAM virtual machine:
Using the following command:

$ apt-get install stress
$ stress --vm-bytes 7500M --vm 1 --vm-keep

RESULTS:

1. Migration throughput: 26 gigabits/second.
2. Downtime (stop time) varies between 15 and 100 milliseconds.

EFFECTS of memory registration on bulk phase round:

For example, in the same 8GB RAM example with all 8GB of memory in
active use and the VM itself is completely idle using the same 40 gbps
infiniband link:

1. x-rdma-pin-all disabled total time: approximately 7.5 seconds @ 9.5 Gbps
2. x-rdma-pin-all enabled total time: approximately 4 seconds @ 26 Gbps

These numbers would of course scale up to whatever size virtual machine
you have to migrate using RDMA.

Enabling this feature does *not* have any measurable affect on
migration *downtime*. This is because, without this feature, all of the
memory will have already been registered already in advance during
the bulk round and does not need to be re-registered during the successive
iteration rounds.

Michael R. Hines (12):
   rdma: add documentation
   rdma: export yield_until_fd_readable()
   rdma: export throughput w/ MigrationStats QMP
   rdma: introduce qemu_get_max_size()
   rdma: introduce qemu_file_mode_is_not_valid()
   rdma: export qemu_fflush()
   rdma: introduce ram_handle_compressed()
   rdma: introduce qemu_ram_foreach_block()
   rdma: new QEMUFileOps hooks
   rdma: introduce capability x-rdma-pin-all
   rdma: core logic
   rdma: send pc.ram

  Makefile.objs                 |    1 +
  arch_init.c                   |   59 +-
  configure                     |   29 +
  docs/rdma.txt                 |  404 ++++++
  exec.c                        |    9 +
  hmp.c                         |    2 +
  include/block/coroutine.h     |    6 +
  include/exec/cpu-common.h     |    5 +
  include/migration/migration.h |   24 +
  include/migration/qemu-file.h |   44 +
  migration-rdma.c              | 2727 +++++++++++++++++++++++++++++++++++++++++
  migration.c                   |   22 +-
  qapi-schema.json              |   12 +-
  qemu-coroutine-io.c           |   23 +
  savevm.c                      |  133 +-
  15 files changed, 3451 insertions(+), 49 deletions(-)
  create mode 100644 docs/rdma.txt
  create mode 100644 migration-rdma.c

--
1.7.10.4




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