Re: [RFC PATCH v1 00/11] Manage the top tier memory in a tiered memory

[Shakeel Butt]

On Thu, Apr 8, 2021 at 1:50 PM Yang Shi <shy828301@xxxxxxxxx> wrote:
>
[...]

> >
> > The low and min limits have semantics similar to the v1's soft limit
> > for this situation i.e. letting the low priority job occupy top tier
> > memory and depending on reclaim to take back the excess top tier
> > memory use of such jobs.
>
> I don't get why low priority jobs can *not* use top tier memory?

I am saying low priority jobs can use top tier memory. The only
difference is to limit them upfront (using limits) or reclaim from
them later (using min/low/soft-limit).

> I can
> think of it may incur latency overhead for high priority jobs. If it
> is not allowed, it could be restricted by cpuset without introducing
> in any new interfaces.
>
> I'm supposed the memory utilization could be maximized by allowing all
> jobs allocate memory from all applicable nodes, then let reclaimer (or
> something new if needed)

Most probably something new as we do want to consider unevictable
memory as well.

> do the job to migrate the memory to proper
> nodes by time. We could achieve some kind of balance between memory
> utilization and resource isolation.
>

Tradeoff between utilization and isolation should be decided by the user/admin.