Hi, I've tested on kvm and encountered similar issue. If I boot up VM with CPU hotplug enabled like below: ./qemu-system-x86_64 -smp 2, maxcpus=4 <other boot parameters>
then the ' /sys/devices/system/cpu/possible' does not equal to the number of cpu* dirs in ' /sys/devices/system/cpu/', which will crash the percpu map testcase. Should we consider fix it, or for simply workaround, we could disable CONFIG_HOTPLUG_CPU? Thanks William On Thu, Aug 18, 2016 at 6:38 PM, William Tu <u9012...@gmail.com> wrote: > Hi Alexei and Daniel, > > I got feedback from Fusion bios/chipset team. In short, the value > 'possible' includes empty CPU socket. To verify, I tested on a > physical Xeon machine with 2 CPU sockets, one of them is empty. I got > 'possible' = 0-239, the number of 'cpu*' =12. As a result, extra bytes > are copied from kernel to userspace. > > As for Fusion, there is a configuration in *.vmx. If we disable cpu > hot plug by "vcpu.hotadd=FALSE", then 'possible' == the number of > 'cpu*' dirs, which is the configuration in ESX. If "vcpu.hotadd=TURE", > then 'possible' is larger than 'cpu*' dirs, allowing users to add more > vcpus. > > Regards, > William > > > On Fri, Aug 12, 2016 at 4:08 PM, Alexei Starovoitov > <alexei.starovoi...@gmail.com> wrote: >> On Fri, Aug 12, 2016 at 09:58:51AM -0700, William Tu wrote: >>> Hi, >>> >>> I've tested on ESXi version 5.5 and it seems OK. >>> - VM1: Ubuntu 14.04, kernel 3.19 ---> OK 3 cpu dirs, possible = 0-2 >>> - VM2: Centos7, kernel 3.10 ---> OK 8 cpu dirs, possible = 0-7 >>> >>> I tried another MacBook with Fusion, same issue happens, the cpu[0-9] >>> dirs are not equal to /sys/devices/system/cpu/possible >> >> great. thanks for testing. I think the issue is closed and >> hopefully you can follow up with fusion guys ;) >>
