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

Avi Kivity
2011-05-30T12:44:35Z

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.
>

Well, strangely, 42-on-1 booted for me in qemu, and only got
ridiculously slow in initrd. Three minutes and it's still booting.

I don't really see how tools/kvm could cause this slowness, though.

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