b9f88dc071
Gathering statistics is important for development, for monitoring and
for performance measurement. There are tools such as kvm_stat that do
this and they rely on the _user_ knowing the interesting data points
rather than the tool (which can treat them as opaque).
The commands introduced in this commit introduce QMP support for
querying stats; the goal is to take the capabilities of these tools
and making them available throughout the whole virtualization stack,
so that one can observe, monitor and measure virtual machines without
having shell access + root on the host that runs them.
query-stats returns a list of all stats per target type (only VM
and vCPU to start); future commits add extra options for specifying
stat names, vCPU qom paths, and providers. All these are used by the
HMP command "info stats". Because of the development usecases around
statistics, a good HMP interface is important.
query-stats-schemas returns a list of stats included in each target
type, with an option for specifying the provider. The concepts in the
schema are based on the KVM binary stats' own introspection data, just
translated to QAPI.
There are two reasons to have a separate schema that is not tied to
the QAPI schema. The first is the contents of the schemas: the new
introspection data provides different information than the QAPI data,
namely unit of measurement, how the numbers are gathered and change
(peak/instant/cumulative/histogram), and histogram bucket sizes.
There's really no reason to have this kind of metadata in the QAPI
introspection schema (except possibly for the unit of measure, but
there's a very weak justification).
Another reason is the dynamicity of the schema. The QAPI introspection
data is very much static; and while QOM is somewhat more dynamic,
generally we consider that to be a bug rather than a feature these days.
On the other hand, the statistics that are exposed by QEMU might be
passed through from another source, such as KVM, and the disadvantages of
manually updating the QAPI schema for outweight the benefits from vetting
the statistics and filtering out anything that seems "too unstable".
Running old QEMU with new kernel is a supported usecase; if old QEMU
cannot expose statistics from a new kernel, or if a kernel developer
needs to change QEMU before gathering new info from the new kernel,
then that is a poor user interface.
The framework provides a method to register callbacks for these QMP
commands. Most of the work in fact is done by the callbacks, and a
large majority of this patch is new QAPI structs and commands.
Examples (with KVM stats):
- Query all VM stats:
{ "execute": "query-stats", "arguments" : { "target": "vm" } }
{ "return": [
{ "provider": "kvm",
"stats": [
{ "name": "max_mmu_page_hash_collisions", "value": 0 },
{ "name": "max_mmu_rmap_size", "value": 0 },
{ "name": "nx_lpage_splits", "value": 148 },
... ] },
{ "provider": "xyz",
"stats": [ ... ] }
] }
- Query all vCPU stats:
{ "execute": "query-stats", "arguments" : { "target": "vcpu" } }
{ "return": [
{ "provider": "kvm",
"qom_path": "/machine/unattached/device[0]"
"stats": [
{ "name": "guest_mode", "value": 0 },
{ "name": "directed_yield_successful", "value": 0 },
{ "name": "directed_yield_attempted", "value": 106 },
... ] },
{ "provider": "kvm",
"qom_path": "/machine/unattached/device[1]"
"stats": [
{ "name": "guest_mode", "value": 0 },
{ "name": "directed_yield_successful", "value": 0 },
{ "name": "directed_yield_attempted", "value": 106 },
... ] },
] }
- Retrieve the schemas:
{ "execute": "query-stats-schemas" }
{ "return": [
{ "provider": "kvm",
"target": "vcpu",
"stats": [
{ "name": "guest_mode",
"unit": "none",
"base": 10,
"exponent": 0,
"type": "instant" },
{ "name": "directed_yield_successful",
"unit": "none",
"base": 10,
"exponent": 0,
"type": "cumulative" },
... ]
},
{ "provider": "kvm",
"target": "vm",
"stats": [
{ "name": "max_mmu_page_hash_collisions",
"unit": "none",
"base": 10,
"exponent": 0,
"type": "peak" },
... ]
},
{ "provider": "xyz",
"target": "vm",
"stats": [ ... ]
}
] }
Signed-off-by: Mark Kanda <mark.kanda@oracle.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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| accel | ||
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| authz | ||
| backends | ||
| block | ||
| bsd-user | ||
| chardev | ||
| common-user | ||
| configs | ||
| contrib | ||
| crypto | ||
| disas | ||
| docs | ||
| dtc@b6910bec11 | ||
| dump | ||
| ebpf | ||
| fpu | ||
| fsdev | ||
| gdb-xml | ||
| hw | ||
| include | ||
| io | ||
| libdecnumber | ||
| linux-headers | ||
| linux-user | ||
| meson@12f9f04ba0 | ||
| migration | ||
| monitor | ||
| nbd | ||
| net | ||
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| python | ||
| qapi | ||
| qga | ||
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| qom | ||
| replay | ||
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| scsi | ||
| semihosting | ||
| slirp@9d59bb775d | ||
| softmmu | ||
| storage-daemon | ||
| stubs | ||
| subprojects/libvhost-user | ||
| target | ||
| tcg | ||
| tests | ||
| tools | ||
| trace | ||
| ui | ||
| util | ||
| .cirrus.yml | ||
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| .editorconfig | ||
| .exrc | ||
| .gdbinit | ||
| .gitattributes | ||
| .gitignore | ||
| .gitlab-ci.yml | ||
| .gitmodules | ||
| .gitpublish | ||
| .mailmap | ||
| .patchew.yml | ||
| .readthedocs.yml | ||
| .travis.yml | ||
| block.c | ||
| blockdev-nbd.c | ||
| blockdev.c | ||
| blockjob.c | ||
| configure | ||
| COPYING | ||
| COPYING.LIB | ||
| cpu.c | ||
| cpus-common.c | ||
| disas.c | ||
| event-loop-base.c | ||
| gdbstub.c | ||
| gitdm.config | ||
| hmp-commands-info.hx | ||
| hmp-commands.hx | ||
| iothread.c | ||
| job-qmp.c | ||
| job.c | ||
| Kconfig | ||
| Kconfig.host | ||
| LICENSE | ||
| MAINTAINERS | ||
| Makefile | ||
| memory_ldst.c.inc | ||
| meson_options.txt | ||
| meson.build | ||
| module-common.c | ||
| os-posix.c | ||
| os-win32.c | ||
| page-vary-common.c | ||
| page-vary.c | ||
| qemu-bridge-helper.c | ||
| qemu-edid.c | ||
| qemu-img-cmds.hx | ||
| qemu-img.c | ||
| qemu-io-cmds.c | ||
| qemu-io.c | ||
| qemu-keymap.c | ||
| qemu-nbd.c | ||
| qemu-options.hx | ||
| qemu.nsi | ||
| qemu.sasl | ||
| README.rst | ||
| replication.c | ||
| trace-events | ||
| VERSION | ||
| version.rc | ||
=========== 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. Documentation ============= Documentation can be found hosted online at `<https://www.qemu.org/documentation/>`_. The documentation for the current development version that is available at `<https://www.qemu.org/docs/master/>`_ is generated from the ``docs/`` folder in the source tree, and is built by `Sphinx <https://www.sphinx-doc.org/en/master/>_`. 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: .. code-block:: shell mkdir build cd build ../configure make Additional information can also be found online via the QEMU website: * `<https://wiki.qemu.org/Hosts/Linux>`_ * `<https://wiki.qemu.org/Hosts/Mac>`_ * `<https://wiki.qemu.org/Hosts/W32>`_ Submitting patches ================== The QEMU source code is maintained under the GIT version control system. .. code-block:: shell git clone https://gitlab.com/qemu-project/qemu.git When submitting patches, one common 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 `style section <https://www.qemu.org/docs/master/devel/style.html>` of the Developers Guide. Additional information on submitting patches can be found online via the QEMU website * `<https://wiki.qemu.org/Contribute/SubmitAPatch>`_ * `<https://wiki.qemu.org/Contribute/TrivialPatches>`_ The QEMU website is also maintained under source control. .. code-block:: shell git clone https://gitlab.com/qemu-project/qemu-web.git * `<https://www.qemu.org/2017/02/04/the-new-qemu-website-is-up/>`_ A 'git-publish' utility was created to make above process less cumbersome, and is highly recommended for making regular contributions, or even just for sending consecutive patch series revisions. It also requires a working 'git send-email' setup, and by default doesn't automate everything, so you may want to go through the above steps manually for once. For installation instructions, please go to * `<https://github.com/stefanha/git-publish>`_ The workflow with 'git-publish' is: .. code-block:: shell $ git checkout master -b my-feature $ # work on new commits, add your 'Signed-off-by' lines to each $ git publish Your patch series will be sent and tagged as my-feature-v1 if you need to refer back to it in the future. Sending v2: .. code-block:: shell $ git checkout my-feature # same topic branch $ # making changes to the commits (using 'git rebase', for example) $ git publish Your patch series will be sent with 'v2' tag in the subject and the git tip will be tagged as my-feature-v2. Bug reporting ============= The QEMU project uses GitLab issues to track bugs. Bugs found when running code built from QEMU git or upstream released sources should be reported via: * `<https://gitlab.com/qemu-project/qemu/-/issues>`_ 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 GitLab. For additional information on bug reporting consult: * `<https://wiki.qemu.org/Contribute/ReportABug>`_ ChangeLog ========= For version history and release notes, please visit `<https://wiki.qemu.org/ChangeLog/>`_ or look at the git history for more detailed information. Contact ======= The QEMU community can be contacted in a number of ways, with the two main methods being email and IRC * `<mailto:qemu-devel@nongnu.org>`_ * `<https://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: * `<https://wiki.qemu.org/Contribute/StartHere>`_