QEMU With E2K User Support
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Nicolas Saenz Julienne 71ad4713cc util/event-loop-base: Introduce options to set the thread pool size
The thread pool regulates itself: when idle, it kills threads until
empty, when in demand, it creates new threads until full. This behaviour
doesn't play well with latency sensitive workloads where the price of
creating a new thread is too high. For example, when paired with qemu's
'-mlock', or using safety features like SafeStack, creating a new thread
has been measured take multiple milliseconds.

In order to mitigate this let's introduce a new 'EventLoopBase'
property to set the thread pool size. The threads will be created during
the pool's initialization or upon updating the property's value, remain
available during its lifetime regardless of demand, and destroyed upon
freeing it. A properly characterized workload will then be able to
configure the pool to avoid any latency spikes.

Signed-off-by: Nicolas Saenz Julienne <nsaenzju@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Acked-by: Markus Armbruster <armbru@redhat.com>
Message-id: 20220425075723.20019-4-nsaenzju@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2022-05-09 10:43:23 +01:00
.github/workflows github: fix config mistake preventing repo lockdown commenting 2022-04-26 16:12:26 +01:00
.gitlab/issue_templates
.gitlab-ci.d tests: Drop perl-Test-Harness from the CI containers / VMs 2022-04-20 08:54:16 +02:00
accel accel/tcg: Assert mmu_idx in range before use in cputlb 2022-04-26 19:57:56 -07:00
audio Remove qemu-common.h include from most units 2022-04-06 14:31:55 +02:00
authz
backends meson: use have_vhost_* variables to pick sources 2022-05-07 07:46:58 +02:00
block block/vmdk: Fix reopening bs->file 2022-05-04 15:55:23 +02:00
bsd-user compiler.h: replace QEMU_NORETURN with G_NORETURN 2022-04-21 17:03:51 +04:00
capstone@f8b1b83301
chardev util: rename qemu_*block() socket functions 2022-05-03 15:53:20 +04:00
common-user common-user/host/sparc64: Fix safe_syscall_base 2022-02-09 08:46:23 +11:00
configs hppa: use new CONFIG_HPPA_B160L option instead of CONFIG_DINO to build hppa machine 2022-05-08 18:52:36 +01:00
contrib util: rename qemu_*block() socket functions 2022-05-03 15:53:20 +04:00
crypto crypto: move sm4_sbox from target/arm 2022-04-29 10:47:45 +10:00
disas disas: Remove old libopcode s390 disassembler 2022-05-04 08:47:19 +02:00
docs meson, configure: move --with-pkgversion, CONFIG_STAMP to meson 2022-05-07 07:46:58 +02:00
dtc@b6910bec11
dump dump/win_dump: add 32-bit guest Windows support 2022-04-22 13:41:56 +04:00
ebpf
fpu softfloat: Use FloatRelation for fracN_cmp 2022-04-26 20:01:55 -07:00
fsdev Remove qemu-common.h include from most units 2022-04-06 14:31:55 +02:00
gdb-xml
hw artist: only render dirty scanlines on the display surface 2022-05-08 18:52:37 +01:00
include util/event-loop-base: Introduce options to set the thread pool size 2022-05-09 10:43:23 +01:00
io util: rename qemu_*block() socket functions 2022-05-03 15:53:20 +04:00
libdecnumber
linux-headers linux-headers: include missing changes from 5.17 2022-03-15 11:50:50 +01:00
linux-user linux-user/nios2: Handle various SIGILL exceptions 2022-04-26 08:17:05 -07:00
meson@12f9f04ba0
migration meson, configure: move RDMA options to meson 2022-04-28 08:52:20 +02:00
monitor vnc: add display-update monitor command. 2022-04-27 10:49:28 -07:00
nbd qapi: nbd-export: allow select bitmaps by node/name pair 2022-04-26 13:15:19 -05:00
net meson: use have_vhost_* variables to pick sources 2022-05-07 07:46:58 +02:00
pc-bios ppc/pnv: Update skiboot to v7.0 2022-04-20 17:58:35 -03:00
plugins osdep: Move memalign-related functions to their own header 2022-03-07 13:16:49 +00:00
po
python python/qmp: remove pylint workaround from legacy.py 2022-04-21 11:01:00 -04:00
qapi util/event-loop-base: Introduce options to set the thread pool size 2022-05-09 10:43:23 +01:00
qga qga-vss: always build qga-vss.tlb when qga-vss.dll is built 2022-05-07 07:46:58 +02:00
qobject include/qapi: add g_autoptr support for qobject types 2022-04-06 10:50:38 +02:00
qom include: add qemu/keyval.h 2022-04-21 17:03:51 +04:00
replay Use g_new() & friends where that makes obvious sense 2022-03-21 15:44:44 +01:00
roms ppc/pnv: Update skiboot to v7.0 2022-04-20 17:58:35 -03:00
scripts configure, meson: move vhost options to Meson 2022-05-07 07:46:59 +02:00
scsi util: replace qemu_get_local_state_pathname() 2022-04-21 17:09:09 +04:00
semihosting semihosting: clean up handling of expanded argv 2022-03-23 10:38:09 +00:00
slirp@a88d9ace23
softmmu remove -writeconfig 2022-04-28 08:51:56 +02:00
storage-daemon include: rename qemu-common.h qemu/help-texts.h 2022-04-21 16:58:24 +04:00
stubs Move error_printf_unless_qmp() with monitor unit 2022-04-21 17:09:09 +04:00
subprojects/libvhost-user vhost-user: Don't pass file descriptor for VHOST_USER_REM_MEM_REG 2022-05-04 15:55:23 +02:00
target * WHPX support for xcr0 2022-05-07 06:14:16 -05:00
tcg tcg: Implement tcg_gen_{h,w}swap_{i32,i64} 2022-05-04 08:47:19 +02:00
tests * WHPX support for xcr0 2022-05-07 06:14:16 -05:00
tools meson: create have_vhost_* variables 2022-05-07 07:46:58 +02:00
trace error: use GLib to remember the program name 2022-03-22 14:46:18 +04:00
ui ui: replace qemu_set_nonblock() 2022-05-03 15:52:37 +04:00
util util/event-loop-base: Introduce options to set the thread pool size 2022-05-09 10:43:23 +01:00
.cirrus.yml tests: Manually remove libxml2 on MSYS2 runners 2022-02-09 12:08:42 +00:00
.dir-locals.el
.editorconfig
.exrc
.gdbinit
.gitattributes gitattributes: Cover Objective-C source files 2022-03-29 00:15:14 +02:00
.gitignore .gitignore: add .gcov pattern 2022-02-09 12:08:41 +00:00
.gitlab-ci.yml
.gitmodules gitmodules: Correct libvirt-ci submodule URL 2022-02-09 12:08:41 +00:00
.gitpublish
.mailmap MAINTAINERS: change Fred Konrad's email address 2022-04-01 15:35:49 +01:00
.patchew.yml
.readthedocs.yml
.travis.yml gitlab: disable accelerated zlib for s390x 2022-03-22 17:07:30 +00:00
block.c block: Classify bdrv_get_flags() as I/O function 2022-05-04 15:55:23 +02:00
blockdev-nbd.c qapi: nbd-export: allow select bitmaps by node/name pair 2022-04-26 13:15:19 -05:00
blockdev.c Replace qemu_gettimeofday() with g_get_real_time() 2022-04-06 10:50:37 +02:00
blockjob.c assertions for blockjob.h global state API 2022-03-04 18:18:25 +01:00
configure configure, meson: move vhost options to Meson 2022-05-07 07:46:59 +02:00
COPYING
COPYING.LIB
cpu.c util/log: Remove qemu_log_close 2022-04-20 10:51:11 -07:00
cpus-common.c Use g_new() & friends where that makes obvious sense 2022-03-21 15:44:44 +01:00
disas.c disas: Remove old libopcode s390 disassembler 2022-05-04 08:47:19 +02:00
event-loop-base.c util/event-loop-base: Introduce options to set the thread pool size 2022-05-09 10:43:23 +01:00
gdbstub.c whpx: Added support for breakpoints and stepping 2022-04-06 14:31:55 +02:00
gitdm.config
hmp-commands-info.hx mos6522: add "info via" HMP command for debugging 2022-03-09 09:28:28 +00:00
hmp-commands.hx vnc: add display-update monitor command. 2022-04-27 10:49:28 -07:00
iothread.c util/event-loop-base: Introduce options to set the thread pool size 2022-05-09 10:43:23 +01:00
job-qmp.c
job.c job.h: assertions in the callers of JobDriver function pointers 2022-03-04 18:18:26 +01:00
Kconfig
Kconfig.host meson: use have_vhost_* variables to pick sources 2022-05-07 07:46:58 +02:00
LICENSE
MAINTAINERS lasi: move from hw/hppa to hw/misc 2022-05-08 18:52:37 +01:00
Makefile Makefile: also remove .gcno files when cleaning 2022-02-09 12:08:41 +00:00
memory_ldst.c.inc
meson_options.txt configure, meson: move vhost options to Meson 2022-05-07 07:46:59 +02:00
meson.build util/main-loop: Introduce the main loop into QOM 2022-05-09 10:43:23 +01:00
module-common.c
os-posix.c os-posix: replace pipe()+cloexec with g_unix_open_pipe(CLOEXEC) 2022-05-03 15:46:17 +04:00
os-win32.c Remove qemu-common.h include from most units 2022-04-06 14:31:55 +02:00
page-vary-common.c Remove qemu-common.h include from most units 2022-04-06 14:31:55 +02:00
page-vary.c include: move target page bits declaration to page-vary.h 2022-04-06 14:31:43 +02:00
qemu-bridge-helper.c
qemu-edid.c edid: set default resolution to 1280x800 (WXGA) 2022-01-13 10:59:16 +01:00
qemu-img-cmds.hx qemu-img: Unify [-b [-F]] documentation 2022-02-01 13:49:15 +01:00
qemu-img.c qapi: rename BlockDirtyBitmapMergeSource to BlockDirtyBitmapOrStr 2022-04-26 13:13:50 -05:00
qemu-io-cmds.c nbd patches for 2022-03-07 2022-03-09 11:38:29 +00:00
qemu-io.c include: rename qemu-common.h qemu/help-texts.h 2022-04-21 16:58:24 +04:00
qemu-keymap.c
qemu-nbd.c Replace qemu_pipe() with g_unix_open_pipe() 2022-05-03 15:17:56 +04:00
qemu-options.hx qemu-options: Limit the -enable-kvm option to the targets that support it 2022-04-28 08:52:22 +02:00
qemu.nsi nsis installer: Fix mouse-over descriptions for emulators 2022-03-18 10:55:15 +00:00
qemu.sasl
README.rst
replication.c
trace-events tracing: remove TCG memory access tracing 2022-02-09 12:08:42 +00:00
VERSION Open 7.1 development tree 2022-04-19 18:21:23 -07:00
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>`_