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

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Date:   Thu, 4 May 2023 11:47:42 -0700
From:   Hao Luo <haoluo@...gle.com>
To:     Michal Hocko <mhocko@...e.com>
Cc:     Frank van der Linden <fvdl@...gle.com>,
        lsf-pc@...ts.linux-foundation.org, linux-mm@...ck.org,
        LKML <linux-kernel@...r.kernel.org>, bpf <bpf@...r.kernel.org>,
        Yu Zhao <yuzhao@...gle.com>,
        Alexei Starovoitov <ast@...nel.org>,
        Song Liu <song@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Andrii Nakryiko <andrii@...nel.org>,
        Martin KaFai Lau <martin.lau@...ux.dev>
Subject: Re: [Lsf-pc] Fwd: [LSF/MM/BPF TOPIC] userspace control of memory management

On Fri, Apr 28, 2023 at 7:18 AM Michal Hocko <mhocko@...e.com> wrote:
>
> 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@...gle.com>
> > Date: Tue, Feb 28, 2023 at 4:15 PM
> > Subject: [LSF/MM/BPF TOPIC] userspace control of memory management
> > To: <linux-mm@...ck.org>
> >
> >
> > 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
> > _______________________________________________

Please allow me to cc bpf mailing list for visibility. The idea seems
interesting.

Hao