Re: [PATCH v8 0/4] introduce memory hinting API for external process

Minchan Kim
2020-06-22T19:36:41Z

On Mon, Jun 22, 2020 at 12:28:56PM -0700, Minchan Kim wrote:
> Now, we have MADV_PAGEOUT and MADV_COLD as madvise hinting API. With that,
> application could give hints to kernel what memory range are preferred to be
> reclaimed. However, in some platform(e.g., Android), the information
> required to make the hinting decision is not known to the app.
> Instead, it is known to a centralized userspace daemon(e.g., ActivityManagerService),
> and that daemon must be able to initiate reclaim on its own without any app
> involvement.
>
> To solve the concern, this patch introduces new syscall - process_madvise(2).
> Bascially, it's same with madvise(2) syscall but it has some differences.
>
> 1. It needs pidfd of target process to provide the hint
> 2. It supports only MADV_{COLD|PAGEOUT} at this moment.
> Other hints in madvise will be opened when there are explicit requests from
> community to prevent unexpected bugs we couldn't support.
> 3. Only privileged processes can do something for other process's address
> space.
>
> For more detail of the new API, please see "mm: introduce external memory hinting API"
> description in this patchset.
>
> * from v7 - http://lore.kernel.org/r/20200302193630.68771-1-minchan@kernel.org
> * dropping pid support from new syscall and fold releated patches into syscall patch
> * dropping KSM patch by discussion - Oleksandr, I lost the discussion.
> Please resend the single patch against of the patchset if you resolves the discussion.
> https://lore.kernel.org/linux-api/20200302193630.68771-8-minchan@kernel.org/

Oleksandr, it seems you discussed something with Vlastimil but couldn't
find conclustion yet and Since Jann put an a new note in the thread,
I detach the patch from this patchset.

Please send the KSM patch based on this patchset if you belive there is
no need to be actionable for comments.