Re: [PATCH v2 6/8] kvm tools: Add rwlock wrapper

[Avi Kivity <avi@redhat.com>]

On 05/30/2011 03:36 PM, Ingo Molnar wrote:
> You are probably right about 1024 CPUs.
>
> Right now i can produce something similar to it: 42 vcpus on a single
> CPU:
>
> 	$ taskse 1 kvm run --cpus 42
>
> And that hangs early on during bootup, around:
>
> [    0.236000] Disabled fast string operations
> [    0.242000]  #4
> [    0.270000] Disabled fast string operations
> [    0.275000]  #5
> [    0.317000] Disabled fast string operations
> [    0.322000]  #6
> [    0.352000] Disabled fast string operations
> [    0.358000]  #7
> [    0.414000] Disabled fast string operations
>
> The threads seem to be livelocked:
>
>    PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND
> 22227 mingo     20   0  471g  95m  904 R 12.9  0.8   0:06.39 kvm
> 22230 mingo     20   0  471g  95m  904 R 12.9  0.8   0:06.36 kvm
> 22226 mingo     20   0  471g  95m  904 R 11.9  0.8   0:07.04 kvm
> 22228 mingo     20   0  471g  95m  904 R 11.9  0.8   0:06.38 kvm
> 22229 mingo     20   0  471g  95m  904 R 11.9  0.8   0:06.37 kvm
> 22231 mingo     20   0  471g  95m  904 R 11.9  0.8   0:06.37 kvm
> 22232 mingo     20   0  471g  95m  904 R 11.9  0.8   0:06.36 kvm
> 22233 mingo     20   0  471g  95m  904 R 11.9  0.8   0:06.33 kvm
>      7 root      -2  19     0    0    0 S  2.0  0.0   1:12.53 rcuc0
>
> with no apparent progress being made.
>


Does your host kernel include 8fa2206821953 ("KVM: make guest mode entry 
to be rcu quiescent state")?

I'm guessing it does, and that it doesn't matter anyway (you have a lot 
of ordinary host context switches), but it doesn't hurt to check.

-- 
error compiling committee.c: too many arguments to function