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This introduces a moderately general purpose framework for
testing performance of migration.
The initial guest workload is provided by the included 'stress'
program, which is configured to spawn one thread per guest CPU
and run a maximally memory intensive workload. It will loop
over GB of memory, xor'ing each byte with data from a 4k array
of random bytes. This ensures heavy read and write load across
all of guest memory to stress the migration performance. While
running the 'stress' program will record how long it takes to
xor each GB of memory and print this data for later reporting.
The test engine will spawn a pair of QEMU processes, either on
the same host, or with the target on a remote host via ssh,
using the host kernel and a custom initrd built with 'stress'
as the /init binary. Kernel command line args are set to ensure
a fast kernel boot time (< 1 second) between launching QEMU and
the stress program starting execution.
None the less, the test engine will initially wait N seconds for
the guest workload to stablize, before starting the migration
operation. When migration is running, the engine will use pause,
post-copy, autoconverge, xbzrle compression and multithread
compression features, as well as downtime & bandwidth tuning
to encourage completion. If migration completes, the test engine
will wait N seconds again for the guest workooad to stablize on
the target host. If migration does not complete after a preset
number of iterations, it will be aborted.
While the QEMU process is running on the source host, the test
engine will sample the host CPU usage of QEMU as a whole, and
each vCPU thread. While migration is running, it will record
all the stats reported by 'query-migration'. Finally, it will
capture the output of the stress program running in the guest.
All the data produced from a single test execution is recorded
in a structured JSON file. A separate program is then able to
create interactive charts using the "plotly" python + javascript
libraries, showing the characteristics of the migration.
The data output provides visualization of the effect on guest
vCPU workloads from the migration process, the corresponding
vCPU utilization on the host, and the overall CPU hit from
QEMU on the host. This is correlated from statistics from the
migration process, such as downtime, vCPU throttling and iteration
number.
While the tests can be run individually with arbitrary parameters,
there is also a facility for producing batch reports for a number
of pre-defined scenarios / comparisons, in order to be able to
get standardized results across different hardware configurations
(eg TCP vs RDMA, or comparing different VCPU counts / memory
sizes, etc).
To use this, first you must build the initrd image
$ make tests/migration/initrd-stress.img
To run a a one-shot test with all default parameters
$ ./tests/migration/guestperf.py > result.json
This has many command line args for varying its behaviour.
For example, to increase the RAM size and CPU count and
bind it to specific host NUMA nodes
$ ./tests/migration/guestperf.py \
--mem 4 --cpus 2 \
--src-mem-bind 0 --src-cpu-bind 0,1 \
--dst-mem-bind 1 --dst-cpu-bind 2,3 \
> result.json
Using mem + cpu binding is strongly recommended on NUMA
machines, otherwise the guest performance results will
vary wildly between runs of the test due to lucky/unlucky
NUMA placement, making sensible data analysis impossible.
To make it run across separate hosts:
$ ./tests/migration/guestperf.py \
--dst-host somehostname > result.json
To request that post-copy is enabled, with switchover
after 5 iterations
$ ./tests/migration/guestperf.py \
--post-copy --post-copy-iters 5 > result.json
Once a result.json file is created, a graph of the data
can be generated, showing guest workload performance per
thread and the migration iteration points:
$ ./tests/migration/guestperf-plot.py --output result.html \
--migration-iters --split-guest-cpu result.json
To further include host vCPU utilization and overall QEMU
utilization
$ ./tests/migration/guestperf-plot.py --output result.html \
--migration-iters --split-guest-cpu \
--qemu-cpu --vcpu-cpu result.json
NB, the 'guestperf-plot.py' command requires that you have
the plotly python library installed. eg you must do
$ pip install --user plotly
Viewing the result.html file requires that you have the
plotly.min.js file in the same directory as the HTML
output. This js file is installed as part of the plotly
python library, so can be found in
$HOME/.local/lib/python2.7/site-packages/plotly/offline/plotly.min.js
The guestperf-plot.py program can accept multiple json files
to plot, enabling results from different configurations to
be compared.
Finally, to run the entire standardized set of comparisons
$ ./tests/migration/guestperf-batch.py \
--dst-host somehost \
--mem 4 --cpus 2 \
--src-mem-bind 0 --src-cpu-bind 0,1 \
--dst-mem-bind 1 --dst-cpu-bind 2,3
--output tcp-somehost-4gb-2cpu
will store JSON files from all scenarios in the directory
named tcp-somehost-4gb-2cpu
Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
Message-Id: <1469020993-29426-7-git-send-email-berrange@redhat.com>
Signed-off-by: Amit Shah <amit.shah@redhat.com>
QEMU README
===========
QEMU is a generic and open source machine & userspace emulator and
virtualizer.
QEMU is capable of emulating a complete machine in software without any
need for hardware virtualization support. By using dynamic translation,
it achieves very good performance. QEMU can also integrate with the Xen
and KVM hypervisors to provide emulated hardware while allowing the
hypervisor to manage the CPU. With hypervisor support, QEMU can achieve
near native performance for CPUs. When QEMU emulates CPUs directly it is
capable of running operating systems made for one machine (e.g. an ARMv7
board) on a different machine (e.g. an x86_64 PC board).
QEMU is also capable of providing userspace API virtualization for Linux
and BSD kernel interfaces. This allows binaries compiled against one
architecture ABI (e.g. the Linux PPC64 ABI) to be run on a host using a
different architecture ABI (e.g. the Linux x86_64 ABI). This does not
involve any hardware emulation, simply CPU and syscall emulation.
QEMU aims to fit into a variety of use cases. It can be invoked directly
by users wishing to have full control over its behaviour and settings.
It also aims to facilitate integration into higher level management
layers, by providing a stable command line interface and monitor API.
It is commonly invoked indirectly via the libvirt library when using
open source applications such as oVirt, OpenStack and virt-manager.
QEMU as a whole is released under the GNU General Public License,
version 2. For full licensing details, consult the LICENSE file.
Building
========
QEMU is multi-platform software intended to be buildable on all modern
Linux platforms, OS-X, Win32 (via the Mingw64 toolchain) and a variety
of other UNIX targets. The simple steps to build QEMU are:
mkdir build
cd build
../configure
make
Complete details of the process for building and configuring QEMU for
all supported host platforms can be found in the qemu-tech.html file.
Additional information can also be found online via the QEMU website:
http://qemu-project.org/Hosts/Linux
http://qemu-project.org/Hosts/W32
Submitting patches
==================
The QEMU source code is maintained under the GIT version control system.
git clone git://git.qemu-project.org/qemu.git
When submitting patches, the preferred approach is to use 'git
format-patch' and/or 'git send-email' to format & send the mail to the
qemu-devel@nongnu.org mailing list. All patches submitted must contain
a 'Signed-off-by' line from the author. Patches should follow the
guidelines set out in the HACKING and CODING_STYLE files.
Additional information on submitting patches can be found online via
the QEMU website
http://qemu-project.org/Contribute/SubmitAPatch
http://qemu-project.org/Contribute/TrivialPatches
Bug reporting
=============
The QEMU project uses Launchpad as its primary upstream bug tracker. Bugs
found when running code built from QEMU git or upstream released sources
should be reported via:
https://bugs.launchpad.net/qemu/
If using QEMU via an operating system vendor pre-built binary package, it
is preferable to report bugs to the vendor's own bug tracker first. If
the bug is also known to affect latest upstream code, it can also be
reported via launchpad.
For additional information on bug reporting consult:
http://qemu-project.org/Contribute/ReportABug
Contact
=======
The QEMU community can be contacted in a number of ways, with the two
main methods being email and IRC
- qemu-devel@nongnu.org
http://lists.nongnu.org/mailman/listinfo/qemu-devel
- #qemu on irc.oftc.net
Information on additional methods of contacting the community can be
found online via the QEMU website:
http://qemu-project.org/Contribute/StartHere
-- End