Re: [Qemu-devel] [PATCH v3] rcu: reduce more than 7MB heap memory by malloc_trim()

[Paolo Bonzini]

On 27/11/2017 04:06, Zhong Yang wrote:
>   #test command
>   ./qemu-system-x86_64 -enable-kvm -cpu host -m 2G -smp cpus=4,cores=4,\
>                        threads=1,sockets=1 -drive format=raw,\
>                        file=test.img,index=0,media=disk -nographic
> 
>   #without patch
>   address@hidden:~# systemd-analyze
>   Startup finished in 4.979s (kernel) + 1.214s (userspace) = 6.193s
> 
>   address@hidden:~# systemd-analyze
>   Startup finished in 4.922s (kernel) + 1.175s (userspace) = 6.097s
> 
>   address@hidden:~# systemd-analyze
>   Startup finished in 4.990s (kernel) + 1.301s (userspace) = 6.291s
> 
>   address@hidden:~# systemd-analyze
>   Startup finished in 5.063s (kernel) + 1.336s (userspace) = 6.400s
> 
>   address@hidden:~# systemd-analyze
>   Startup finished in 4.820s (kernel) + 1.237s (userspace) = 6.057s
> 
>   avg: kernel 4.9548, userspace 1.2526
> 
> 
>   #with this patch
>   address@hidden:~# systemd-analyze
>   Startup finished in 5.099s (kernel) + 1.579s (userspace) = 6.679s
> 
>   address@hidden:~# systemd-analyze
>   Startup finished in 5.003s (kernel) + 1.343s (userspace) = 6.347s
> 
>   address@hidden:~# systemd-analyze
>   Startup finished in 4.853s (kernel) + 1.220s (userspace) = 6.074s
> 
>   address@hidden:~# systemd-analyze
>   Startup finished in 4.836s (kernel) + 1.111s (userspace) = 5.948s
> 
>   address@hidden:~# systemd-analyze
>   Startup finished in 4.917s (kernel) + 1.166s (userspace) = 6.083s
> 
>   avg: kernel 4.9416s, userspace: 1.2838
> 
>   From above test results, there are almost not any performance regression
>   on x86 platform. Sorry, there is not any ARM based platform in my hand,
>   i can't give related datas.  thanks!

You are using only one disk, Shannon is using 200.  That may make a
difference, as PCI BAR setup in the guest becomes very expensive as you
add more devices.

Thanks,

Paolo