[libvirt] [PATCH 0/8] RFC New API to retrieve host node CPU map

Rationale: In order to use the APIs listed below it is necessary for a client to know the maximum number of node CPUs which is passed via the maplen argument. virDomainGetEmulatorPinInfo virDomainGetVcpuPinInfo virDomainGetVcpus virDomainPinEmulator virDomainPinVcpu virDomainPinVcpuFlags The current approach uses virNodeGetInfo to determine the maximum CPU number. This can lead to incorrect results if not all node CPUs are online. The maximum CPU number should always be the number of CPUs present on the host, regardless of their online/offline state. The following example illustrates the issue: Host has 3 logical CPUs, 1 socket, 3 cores, 1 thread. Guest has 1 virtual CPU and is started while all 3 host CPUs are online. $ virsh vcpuinfo guest VCPU: 0 CPU: 0 State: running CPU time: 35.4s CPU Affinity: yyy $ echo 0 > /sys/devices/system/cpu/cpu1/online $ virsh vcpuinfo guest VCPU: 0 CPU: 0 State: running CPU time: 35.5s CPU Affinity: y- The correct display for CPU affinity would have been y-y, as the guest continues to use CPUs 0 and 2. This is not a display problem only, because it is also not possible to explicitly pin the virtual CPU to host CPUs 0 and 2, due to the truncated CPU mask. PROPOSAL: To help solve the issue above I suggest a new public API: int virNodeGetCPUMapFlags(virConnectPtr conn, unsigned char **cpumap, unsigned int *online, unsigned int flags); The function will return the number of CPUs present on the host or -1 on failure; If cpumap is non-NULL virNodeGetCPUMapFlags will allocate an array containing a bit map representation of the online CPUs. It's the callers responsibility to deallocate cpumap using free(). If online is non-NULL, the variable pointed to will contain the number of online host node CPUs. The variable flags has been added to support future extensions and must be set to 0. Clients can use virNodeGetCPUMapFlags to properly determine the maximum number of node CPUs and their online/offline state. Remarks: This series implements the QEMU and test drivers. This series doesn't introduce changes to the existing vcpu pinning, which I would submit as a succeeding patch set. No python binding yet. Viktor Mihajlovski (8): virNodeGetCPUMapFlags: Define public API. virNodeGetCPUMapFlags: Define driver API. virNodeGetCPUMapFlags: Implement public API. virNodeGetCPUMapFlags: Implement wire protocol. libvirt.h.in: Add new cpumap macro VIR_CPU_USED virNodeGetCPUMapFlags: Implement virsh support. virNodeGetCPUMapFlags: Implement support function in nodeinfo virNodeGetCPUMapFlags: Implement driver support daemon/remote.c | 44 +++++++++++++++++++++++++++++++++ include/libvirt/libvirt.h.in | 28 ++++++++++++++++++--- python/generator.py | 1 + src/driver.h | 7 +++++ src/libvirt.c | 56 ++++++++++++++++++++++++++++++++++++++++++ src/libvirt_private.syms | 1 + src/libvirt_public.syms | 5 +++ src/nodeinfo.c | 49 ++++++++++++++++++++++++++++++++++++ src/nodeinfo.h | 6 ++++ src/qemu/qemu_driver.c | 1 + src/remote/remote_driver.c | 49 ++++++++++++++++++++++++++++++++++++ src/remote/remote_protocol.x | 13 +++++++++- src/remote_protocol-structs | 12 +++++++++ src/test/test_driver.c | 30 ++++++++++++++++++++++ tools/virsh-host.c | 41 ++++++++++++++++++++++++++++++ tools/virsh.pod | 5 +++ 16 files changed, 343 insertions(+), 5 deletions(-)