On Tue, 18 Feb 2020 17:44:26 -0800 Minchan Kim [off-list ref] 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.

This patchset doesn't seem to be getting a lot of interest from other
potential users?  It seems very specialized.  Are there or will there
ever be any users of this apart from one Android daemon?

Also, it doesn't terribly hard for ActivityManagerService to tell
another process "now run madvise with these arguments".  Please explain
why this is not practical in ActivityManagerService and also within
other potential users of this syscall.