Re: [Lsf-pc] Fwd: [LSF/MM/BPF TOPIC] userspace control of memory management

From: Michal Hocko
Date: Fri Apr 28 2023 - 10:18:22 EST


For some reason I cannot find this email in my linux-mm inbox and I
cannot find it in any archives so let me add linux-mm and lkml again for
future reference.

On Tue 28-02-23 21:20:57, Frank van der Linden via Lsf-pc wrote:
> ---------- Forwarded message ---------
> From: Frank van der Linden <fvdl@xxxxxxxxxx>
> Date: Tue, Feb 28, 2023 at 4:15 PM
> Subject: [LSF/MM/BPF TOPIC] userspace control of memory management
> To: <linux-mm@xxxxxxxxx>
>
>
> I propose this discussion topic for LSF/MM/BPF.
>
> In a world where memory topologies are becoming more complicated, is
> it still possible to have an approach where the kernel deals with
> memory management to everyone's satisfaction?
>
> The answer seemingly has been "not quite", since madvise and mempolicy
> exist. With things like cxl.mem coming into existence, a heterogeneous
> memory setup will become more common.
>
> The number of madvise options keeps growing. There is now a
> process_madvise, and there are proposed extensions for the mempolicy
> systemcalls, allowing one process to control the policy of another, as
> well. There are exported cgroup interfaces to control reclaim, and
> discussions have taken place on explicit control reclaim-as-demotion
> to other nodes.
>
> Is this the right approach? If so, would it be a good idea to
> optionally provide BPF hooks to control certain behavior, and let
> userspace direct things even more? Is that even possible,
> performance-wise? Would it make sense to be able to influence the
> MGLRU generation process in a more direct way if needed?
>
> I think a discussion about these points would be interesting. Or, I
> should say, further discussion.
>
> What do you think?
>
> Thanks,
>
> - Frank
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--
Michal Hocko
SUSE Labs