From: Michal Hocko <mhocko@suse.com>
To: Wei Xu <weixugc@google.com>
Cc: Mina Almasry <almasrymina@google.com>,
Andrew Morton <akpm@linux-foundation.org>,
Johannes Weiner <hannes@cmpxchg.org>,
Roman Gushchin <roman.gushchin@linux.dev>,
Shakeel Butt <shakeelb@google.com>,
Muchun Song <songmuchun@bytedance.com>,
Huang Ying <ying.huang@intel.com>,
Yang Shi <yang.shi@linux.alibaba.com>,
Yosry Ahmed <yosryahmed@google.com>,
fvdl@google.com, linux-mm@kvack.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v3] [mm-unstable] mm: Fix memcg reclaim on memory tiered systems
Date: Fri, 9 Dec 2022 22:16:08 +0100 [thread overview]
Message-ID: <Y5OlmLeDen1c/Nly@dhcp22.suse.cz> (raw)
In-Reply-To: <CAAPL-u8J_sgnAn1ev-cfZh428UOySxh1aYZUFKq1=dr-KrdTsw@mail.gmail.com>
On Fri 09-12-22 08:41:47, Wei Xu wrote:
> On Fri, Dec 9, 2022 at 12:08 AM Michal Hocko <mhocko@suse.com> wrote:
> >
> > On Thu 08-12-22 16:59:36, Wei Xu wrote:
> > [...]
> > > > What I really mean is to add demotion nodes to the nodemask along with
> > > > the set of nodes you want to reclaim from. To me that sounds like a
> > > > more natural interface allowing for all sorts of usecases:
> > > > - free up demotion targets (only specify demotion nodes in the mask)
> > > > - control where to demote (e.g. select specific demotion target(s))
> > > > - do not demote at all (skip demotion nodes from the node mask)
> > >
> > > For clarification, do you mean to add another argument (e.g.
> > > demotion_nodes) in addition to the "nodes" argument?
> >
> > No, nodes=mask argument should control the domain where the memory
> > reclaim should happen. That includes both aging and the reclaim. If the
> > mask doesn't contain any lower tier node then no demotion will happen.
> > If only a subset of lower tiers are specified then only those could be
> > used for the demotion process. Or put it otherwise, the nodemask is not
> > only used to filter out zonelists during reclaim it also restricts
> > migration targets.
> >
> > Is this more clear now?
>
> In that case, how can we request demotion only from toptier nodes
> (without counting any reclaimed bytes from other nodes), which is our
> memory tiering use case?
I am not sure I follow. Could you be more specific please?
> Besides, when both toptier and demotion nodes are specified, the
> demoted pages should only be counted as aging and not be counted
> towards the requested bytes of try_to_free_mem_cgroup_pages(), which
> is what this patch tries to address.
This should be addressed by
http://lkml.kernel.org/r/Y5B1K5zAE0PkjFZx@dhcp22.suse.cz, no?
--
Michal Hocko
SUSE Labs
next prev parent reply other threads:[~2022-12-09 21:16 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-12-06 2:34 [PATCH v3] [mm-unstable] mm: Fix memcg reclaim on memory tiered systems Mina Almasry
2022-12-06 3:13 ` Huang, Ying
2022-12-06 4:15 ` Mina Almasry
2022-12-06 5:22 ` Huang, Ying
2022-12-06 12:20 ` Michal Hocko
2022-12-06 16:06 ` Mina Almasry
2022-12-06 19:55 ` Michal Hocko
2022-12-07 1:22 ` Huang, Ying
2022-12-07 1:55 ` Mina Almasry
2022-12-07 11:12 ` Michal Hocko
2022-12-07 21:43 ` Mina Almasry
2022-12-08 8:09 ` Michal Hocko
2022-12-08 9:00 ` Mina Almasry
2022-12-08 11:54 ` Michal Hocko
2022-12-09 0:59 ` Wei Xu
2022-12-09 8:08 ` Michal Hocko
2022-12-09 16:41 ` Wei Xu
2022-12-09 21:16 ` Michal Hocko [this message]
2022-12-09 21:39 ` Mina Almasry
2022-12-12 8:33 ` Michal Hocko
2022-12-10 8:01 ` Wei Xu
2022-12-12 8:36 ` Michal Hocko
2022-12-06 15:15 ` kernel test robot
2022-12-06 18:17 ` kernel test robot
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