829142699e
It was reported that the performance of tunnelled migration and volume upload/download regressed in 6.9.0, when the virt-ssh-helper is used for remote SSH tunnelling instead of netcat. When seeing data available to read from stdin, or the socket, the current code will allocate at most 1k of extra space in the buffer it has. After writing data to the socket, or stdout, if more than 1k of extra space is in the buffer, it will reallocate to free up that space. This results in a huge number of mallocs when doing I/O, as well as a huge number of syscalls since at most 1k of data will be read/written at a time. Also if writing blocks for some reason, it will continue to read data with no memory bound which is bad. This changes the code to use a 1 MB fixed size buffer in each direction. If that buffer becomes full, it will update the watches to stop reading more data. It will never reallocate the buffer at runtime. This increases the performance by orders of magnitude. Reviewed-by: Daniel Henrique Barboza <danielhb413@gmail.com> Tested-by: Christian Ehrhardt <christian.ehrhardt@canonical.com> Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
Libvirt API for virtualization
Libvirt provides a portable, long term stable C API for managing the virtualization technologies provided by many operating systems. It includes support for QEMU, KVM, Xen, LXC, bhyve, Virtuozzo, VMware vCenter and ESX, VMware Desktop, Hyper-V, VirtualBox and the POWER Hypervisor.
For some of these hypervisors, it provides a stateful management daemon which runs on the virtualization host allowing access to the API both by non-privileged local users and remote users.
Layered packages provide bindings of the libvirt C API into other languages including Python, Perl, PHP, Go, Java, OCaml, as well as mappings into object systems such as GObject, CIM and SNMP.
Further information about the libvirt project can be found on the website:
License
The libvirt C API is distributed under the terms of GNU Lesser General Public License, version 2.1 (or later). Some parts of the code that are not part of the C library may have the more restrictive GNU General Public License, version 2.0 (or later). See the files COPYING.LESSER and COPYING for full license terms & conditions.
Installation
Instructions on building and installing libvirt can be found on the website:
https://libvirt.org/compiling.html
Contributing
The libvirt project welcomes contributions in many ways. For most components the best way to contribute is to send patches to the primary development mailing list. Further guidance on this can be found on the website:
https://libvirt.org/contribute.html
Contact
The libvirt project has two primary mailing lists:
- libvirt-users@redhat.com (for user discussions)
- libvir-list@redhat.com (for development only)
Further details on contacting the project are available on the website: