When starting a domain and there's no vCPU/emulator pinning set, we query the list of all online physical CPUs and set affinity of the child process (which eventually becomes QEMU) to that list. We can't assume libvirtd itself had affinity to all online CPUs and since affinity of the child process is inherited, we should fix it afterwards. But that's not necessarily correct. Users might isolate some physical CPUs and we should avoid touching them unless explicitly told so (i.e. vCPU/emulator pinning told us so). Therefore, when attempting to set affinity to all online CPUs subtract the isolated ones. Before this commit: root@localhost:~# cat /sys/devices/system/cpu/isolated 19,21,23 root@virtlab414:~# taskset -cp $(pgrep qemu) pid 14835's current affinity list: 0-23 After: root@virtlab414:~# taskset -cp $(pgrep qemu) pid 17153's current affinity list: 0-18,20,22 Resolves: https://issues.redhat.com/browse/RHEL-33082 Signed-off-by: Michal Privoznik <mprivozn@xxxxxxxxxx> --- src/qemu/qemu_process.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/src/qemu/qemu_process.c b/src/qemu/qemu_process.c index da2b024f92..ef5338eda3 100644 --- a/src/qemu/qemu_process.c +++ b/src/qemu/qemu_process.c @@ -2334,6 +2334,8 @@ qemuProcessDetectIOThreadPIDs(virDomainObj *vm, static int qemuProcessGetAllCpuAffinity(virBitmap **cpumapRet) { + g_autoptr(virBitmap) isolCpus = NULL; + *cpumapRet = NULL; if (!virHostCPUHasBitmap()) @@ -2342,6 +2344,11 @@ qemuProcessGetAllCpuAffinity(virBitmap **cpumapRet) if (!(*cpumapRet = virHostCPUGetOnlineBitmap())) return -1; + if (!(isolCpus = virHostCPUGetIsolated())) + return -1; + + virBitmapSubtract(*cpumapRet, isolCpus); + return 0; } -- 2.43.2 _______________________________________________ Devel mailing list -- devel@xxxxxxxxxxxxxxxxx To unsubscribe send an email to devel-leave@xxxxxxxxxxxxxxxxx
