New virHostMemGetTHPSize() is introduced which allows caller to obtain THP PMD (Page Middle Directory) size, which is equal to the minimal size that THP can use, taken from kernel doc (Documentation/admin-guide/mm/transhuge.rst): Some userspace (such as a test program, or an optimized memory allocation library) may want to know the size (in bytes) of a transparent hugepage:: cat /sys/kernel/mm/transparent_hugepage/hpage_pmd_size Since this size depends on the host architecture and the kernel it won't change whilst libvirtd is running. Therefore, we can use virOnce() and cache the value. Of course, we can be running under kernel that has THP disabled or has no notion of THP at all. In that case a negative value is returned to signal error. Signed-off-by: Michal Privoznik <mprivozn@redhat.com> Reviewed-by: Ján Tomko <jtomko@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: