From: Yosry Ahmed <yosryahmed@google.com>
To: Tejun Heo <tj@kernel.org>, Michal Hocko <mhocko@kernel.org>,
Roman Gushchin <roman.gushchin@linux.dev>,
Shakeel Butt <shakeelb@google.com>
Cc: Alistair Popple <apopple@nvidia.com>,
linux-mm@kvack.org, cgroups@vger.kernel.org,
linux-kernel@vger.kernel.org, jgg@nvidia.com,
jhubbard@nvidia.com, tjmercier@google.com, hannes@cmpxchg.org,
surenb@google.com, mkoutny@suse.com, daniel@ffwll.ch,
"Daniel P . Berrange" <berrange@redhat.com>,
Alex Williamson <alex.williamson@redhat.com>,
Zefan Li <lizefan.x@bytedance.com>,
Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [PATCH 14/19] mm: Introduce a cgroup for pinned memory
Date: Mon, 6 Feb 2023 15:34:55 -0800 [thread overview]
Message-ID: <CAJD7tkYP_4PbrLumDYaTHN2vh8BmLcmy_hWFDbWeA0p58xmYEw@mail.gmail.com> (raw)
In-Reply-To: <Y+GMbWWP/YhtJQqe@slm.duckdns.org>
On Mon, Feb 6, 2023 at 3:25 PM Tejun Heo <tj@kernel.org> wrote:
>
> On Mon, Feb 06, 2023 at 02:39:17PM -0800, Yosry Ahmed wrote:
> > On Mon, Feb 6, 2023 at 2:36 PM Tejun Heo <tj@kernel.org> wrote:
> > >
> > > On Mon, Feb 06, 2023 at 02:32:10PM -0800, Yosry Ahmed wrote:
> > > > I guess it boils down to which we want:
> > > > (a) Limit the amount of memory processes in a cgroup can be pinned/locked.
> > > > (b) Limit the amount of memory charged to a cgroup that can be pinned/locked.
> > > >
> > > > The proposal is doing (a), I suppose if this was part of memcg it
> > > > would be (b), right?
> > > >
> > > > I am not saying it should be one or the other, I am just making sure
> > > > my understanding is clear.
> > >
> > > I don't quite understand what the distinction would mean in practice. It's
> > > just odd to put locked memory in a separate controller from interface POV.
> >
> > Assume we have 2 cgroups, A and B. A process in cgroup A creates a
> > tmpfs file and writes to it, so the memory is now charged to cgroup A.
> > Now imagine a process in cgroup B tries to lock this memory.
> > - With (a) the amount of locked memory will count toward's cgroup A's
> > limit, because cgroup A is charged for the memory.
> > - With (b) the amount of locked memory will count toward's cgroup B's
> > limit, because a process in cgroup B is locking the memory.
> >
> > I agree that it is confusing from an interface POV.
>
> Oh yeah, that's confusing. I'd go with (a) for consistency with the rest of
> memcg - locked memory should fit inside e.g. memory.max. The problem with
> shared memory accounting exists for non-locked memory as well and prolly
> best to handle the same way rather than handling differently.
+Michal Hocko +Roman Gushchin +Shakeel Butt for visibility with memcg.
>
> Thanks.
>
> --
> tejun
next prev parent reply other threads:[~2023-02-06 23:35 UTC|newest]
Thread overview: 71+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-02-06 7:47 [PATCH 00/19] mm: Introduce a cgroup to limit the amount of locked and pinned memory Alistair Popple
2023-02-06 7:47 ` [PATCH 01/19] mm: Introduce vm_account Alistair Popple
2023-02-06 7:47 ` [PATCH 02/19] drivers/vhost: Convert to use vm_account Alistair Popple
2023-02-06 7:47 ` [PATCH 03/19] drivers/vdpa: Convert vdpa to use the new vm_structure Alistair Popple
2023-02-06 7:47 ` [PATCH 04/19] infiniband/umem: Convert to use vm_account Alistair Popple
2023-02-06 7:47 ` [PATCH 05/19] RMDA/siw: " Alistair Popple
2023-02-12 17:32 ` Bernard Metzler
2023-02-06 7:47 ` [PATCH 06/19] RDMA/usnic: convert " Alistair Popple
2023-02-06 7:47 ` [PATCH 07/19] vfio/type1: Charge pinned pages to pinned_vm instead of locked_vm Alistair Popple
2023-02-06 7:47 ` [PATCH 08/19] vfio/spapr_tce: Convert accounting to pinned_vm Alistair Popple
2023-02-06 7:47 ` [PATCH 09/19] io_uring: convert to use vm_account Alistair Popple
2023-02-06 15:29 ` Jens Axboe
2023-02-07 1:03 ` Alistair Popple
2023-02-07 14:28 ` Jens Axboe
2023-02-07 14:55 ` Jason Gunthorpe
2023-02-07 17:05 ` Jens Axboe
2023-02-13 11:30 ` Alistair Popple
2023-02-06 7:47 ` [PATCH 10/19] net: skb: Switch to using vm_account Alistair Popple
2023-02-06 7:47 ` [PATCH 11/19] xdp: convert to use vm_account Alistair Popple
2023-02-06 7:47 ` [PATCH 12/19] kvm/book3s_64_vio: Convert account_locked_vm() to vm_account_pinned() Alistair Popple
2023-02-06 7:47 ` [PATCH 13/19] fpga: dfl: afu: convert to use vm_account Alistair Popple
2023-02-06 7:47 ` [PATCH 14/19] mm: Introduce a cgroup for pinned memory Alistair Popple
2023-02-06 21:01 ` Yosry Ahmed
2023-02-06 21:14 ` Tejun Heo
2023-02-06 22:32 ` Yosry Ahmed
2023-02-06 22:36 ` Tejun Heo
2023-02-06 22:39 ` Yosry Ahmed
2023-02-06 23:25 ` Tejun Heo
2023-02-06 23:34 ` Yosry Ahmed [this message]
2023-02-06 23:40 ` Jason Gunthorpe
2023-02-07 0:32 ` Tejun Heo
2023-02-07 12:19 ` Jason Gunthorpe
2023-02-15 19:00 ` Michal Hocko
2023-02-15 19:07 ` Jason Gunthorpe
2023-02-16 8:04 ` Michal Hocko
2023-02-16 12:45 ` Jason Gunthorpe
2023-02-21 16:51 ` Tejun Heo
2023-02-21 17:25 ` Jason Gunthorpe
2023-02-21 17:29 ` Tejun Heo
2023-02-21 17:51 ` Jason Gunthorpe
2023-02-21 18:07 ` Tejun Heo
2023-02-21 19:26 ` Jason Gunthorpe
2023-02-21 19:45 ` Tejun Heo
2023-02-21 19:49 ` Tejun Heo
2023-02-21 19:57 ` Jason Gunthorpe
2023-02-22 11:38 ` Alistair Popple
2023-02-22 12:57 ` Jason Gunthorpe
2023-02-22 22:59 ` Alistair Popple
2023-02-23 0:05 ` Christoph Hellwig
2023-02-23 0:35 ` Alistair Popple
2023-02-23 1:53 ` Jason Gunthorpe
2023-02-23 9:12 ` Daniel P. Berrangé
2023-02-23 17:31 ` Jason Gunthorpe
2023-02-23 17:18 ` T.J. Mercier
2023-02-23 17:28 ` Jason Gunthorpe
2023-02-23 18:03 ` Yosry Ahmed
2023-02-23 18:10 ` Jason Gunthorpe
2023-02-23 18:14 ` Yosry Ahmed
2023-02-23 18:15 ` Tejun Heo
2023-02-23 18:17 ` Jason Gunthorpe
2023-02-23 18:22 ` Tejun Heo
2023-02-07 1:00 ` Waiman Long
2023-02-07 1:03 ` Tejun Heo
2023-02-07 1:50 ` Alistair Popple
2023-02-06 7:47 ` [PATCH 15/19] mm/util: Extend vm_account to charge pages against the pin cgroup Alistair Popple
2023-02-06 7:47 ` [PATCH 16/19] mm/util: Refactor account_locked_vm Alistair Popple
2023-02-06 7:47 ` [PATCH 17/19] mm: Convert mmap and mlock to use account_locked_vm Alistair Popple
2023-02-06 7:47 ` [PATCH 18/19] mm/mmap: Charge locked memory to pins cgroup Alistair Popple
2023-02-06 21:12 ` Yosry Ahmed
2023-02-06 7:47 ` [PATCH 19/19] selftests/vm: Add pins-cgroup selftest for mlock/mmap Alistair Popple
2023-02-16 11:01 ` [PATCH 00/19] mm: Introduce a cgroup to limit the amount of locked and pinned memory David Hildenbrand
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