Re: [PATCH RESEND v6 0/5] migration: reduce time of loading non-iterable vmstate

[Chuang Xu <xuchuangxclwt@bytedance.com>]

Hi, Peter,

On 2023/3/8 下午10:58, Peter Xu wrote:
> On Wed, Mar 08, 2023 at 06:03:45AM -0800, Chuang Xu wrote:
>> IIUC, Do you mean that different ways to get flatview are tricky?
> Yes, and properly define when to use which.
>
>> As you said, it's slightly beyond what this series does. Maybe it would be
>> better if we discuss it in a new series and keep this series at v6?
>> what's your take?
> Quotting your test result:
>
>                          time of loading non-iterable vmstate
> before                                  112 ms
> long's patch applied                    103 ms
> my patch applied                         44 ms
> both applied                             39 ms
> add as_to_flat_rcu                       19 ms
>
> If introducing address_space_to_flatview_rcu() can further half the time,
> maybe still worth it?
>
> The thing is the extra _rcu() doesn't bring the major complexity, IMHO.  It
> brings some on identifying which is really safe to not reference a latest
> flatview (it seems to me only during a commit() hook..).
>
> The major complexity still comes from the nested enforced commit() during
> address_space_to_flatview() but that is already in the patchset.
>
> Thanks,
>
OK, let me continue to finish v7.

Here I list some TODOs in v7:

1. squash fix into patch1 of yours.
2. introduce address_space_to_flatview_rcu()
3. add specific comment to define when to use which as_to_flat()
4. Does enforce commit() need further modification or keep current status?
    Looks like you have some new thoughts on it?

Are there any other missing points?

Thanks!