mirror of
https://github.com/Motorhead1991/qemu.git
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Official QEMU mirror. Please see https://www.qemu.org/contribute/ for how to submit changes to QEMU. Pull Requests are ignored. Please only use release tarballs from the QEMU website.
http://www.qemu.org
8836630f5d
Currently, the spapr-vlan device is trying to flush the RX queue after each RX buffer that has been added by the guest via the H_ADD_LOGICAL_LAN_BUFFER hypercall. In case the receive buffer pool was empty before, we only pass single packets to the guest this way. This can cause very bad performance if a sender is trying to stream fragmented UDP packets to the guest. For example when using the UDP_STREAM test from netperf with UDP packets that are much bigger than the MTU size, almost all UDP packets are dropped in the guest since the chances are quite high that at least one of the fragments got lost on the way. When flushing the receive queue, it's much better if we'd have a bunch of receive buffers available already, so that fragmented packets can be passed to the guest in one go. To do this, the spapr_vlan_receive() function should return 0 instead of -1 if there are no more receive buffers available, so that receive_disabled = 1 gets temporarily set for the receive queue, and we have to delay the queue flushing at the end of h_add_logical_lan_buffer() a little bit by using a timer, so that the guest gets a chance to add multiple RX buffers before we flush the queue again. This improves the UDP_STREAM test with the spapr-vlan device a lot: Running netserver -p 44444 -L <guestip> -f -D -4 in the guest, and netperf -p 44444 -L <hostip> -H <guestip> -t UDP_STREAM -l 60 -- -m 16384 in the host, I get the following values _without_ this patch: Socket Message Elapsed Messages Size Size Time Okay Errors Throughput bytes bytes secs # # 10^6bits/sec 229376 16384 60.00 1738970 0 3798.83 229376 60.00 23 0.05 That "0.05" means that almost all UDP packets got lost/discarded at the receiving side. With this patch applied, the value look much better: Socket Message Elapsed Messages Size Size Time Okay Errors Throughput bytes bytes secs # # 10^6bits/sec 229376 16384 60.00 1789104 0 3908.35 229376 60.00 22818 49.85 Signed-off-by: Thomas Huth <thuth@redhat.com> Signed-off-by: David Gibson <david@gibson.dropbear.id.au> |
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| block | ||
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| default-configs | ||
| disas | ||
| docs | ||
| dtc@65cc4d2748 | ||
| fpu | ||
| fsdev | ||
| gdb-xml | ||
| hw | ||
| include | ||
| io | ||
| libdecnumber | ||
| linux-headers | ||
| linux-user | ||
| migration | ||
| nbd | ||
| net | ||
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| pixman@87eea99e44 | ||
| po | ||
| qapi | ||
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| replay | ||
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| async.c | ||
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| bootdevice.c | ||
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| Changelog | ||
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| configure | ||
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| cpus.c | ||
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| device-hotplug.c | ||
| device_tree.c | ||
| disas.c | ||
| dma-helpers.c | ||
| dump.c | ||
| exec.c | ||
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| HACKING | ||
| hmp-commands-info.hx | ||
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| hmp.c | ||
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| iohandler.c | ||
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| LICENSE | ||
| main-loop.c | ||
| MAINTAINERS | ||
| Makefile | ||
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| qapi-schema.json | ||
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| qdict-test-data.txt | ||
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| qemu-doc.texi | ||
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| qemu-img.texi | ||
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| qemu-nbd.c | ||
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| README | ||
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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