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

[Paolo Bonzini]

On 07/12/2017 16:06, Yang Zhong wrote:
>  Which show trim cost time less than 1ms and call_rcu_thread() do 10 times 
> batch free, the trim also 10 times.
> 
>  I also did below changes: 
>     delta=1000,  and 
>     next_trim_time = qemu_clock_get_ns(QEMU_CLOCK_HOST) + delta * 
> last_trim_time
> 
>  The whole VM bootup will trim 3 times.

For any adaptive mechanism (either this one or the simple "if (n == 0)"
one), the question is:

1) what effect it has on RSS in your case

2) what effect it has on boot time in Shannon's case.

Either patch is okay if you can justify it with these two performance
indices.

Thanks,

Paolo