From: Wei Xu <weixugc@google.com>
To: "Huang, Ying" <ying.huang@intel.com>
Cc: Michal Hocko <mhocko@suse.com>,
Yosry Ahmed <yosryahmed@google.com>,
Johannes Weiner <hannes@cmpxchg.org>,
Shakeel Butt <shakeelb@google.com>,
Andrew Morton <akpm@linux-foundation.org>,
David Rientjes <rientjes@google.com>, Tejun Heo <tj@kernel.org>,
Zefan Li <lizefan.x@bytedance.com>,
Roman Gushchin <roman.gushchin@linux.dev>,
cgroups@vger.kernel.org, linux-doc@vger.kernel.org,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Linux MM <linux-mm@kvack.org>, Jonathan Corbet <corbet@lwn.net>,
Yu Zhao <yuzhao@google.com>,
Dave Hansen <dave.hansen@linux.intel.com>,
Greg Thelen <gthelen@google.com>
Subject: Re: [PATCH resend] memcg: introduce per-memcg reclaim interface
Date: Sat, 2 Apr 2022 23:56:19 -0700 [thread overview]
Message-ID: <CAAPL-u8wjtBRE7KZyZjoQ0eTJecnW35uEXAE3KU0M+AvL=5-ug@mail.gmail.com> (raw)
In-Reply-To: <87y20nzyw4.fsf@yhuang6-desk2.ccr.corp.intel.com>
On Sat, Apr 2, 2022 at 1:13 AM Huang, Ying <ying.huang@intel.com> wrote:
>
> Wei Xu <weixugc@google.com> writes:
>
> > On Fri, Apr 1, 2022 at 6:54 AM Michal Hocko <mhocko@suse.com> wrote:
> >>
> >> On Thu 31-03-22 08:41:51, Yosry Ahmed wrote:
> >> > From: Shakeel Butt <shakeelb@google.com>
> >> >
>
> [snip]
>
> >> > Possible Extensions:
> >> > --------------------
> >> >
> >> > - This interface can be extended with an additional parameter or flags
> >> > to allow specifying one or more types of memory to reclaim from (e.g.
> >> > file, anon, ..).
> >> >
> >> > - The interface can also be extended with a node mask to reclaim from
> >> > specific nodes. This has use cases for reclaim-based demotion in memory
> >> > tiering systens.
> >> >
> >> > - A similar per-node interface can also be added to support proactive
> >> > reclaim and reclaim-based demotion in systems without memcg.
> >> >
> >> > For now, let's keep things simple by adding the basic functionality.
> >>
> >> Yes, I am for the simplicity and this really looks like a bare minumum
> >> interface. But it is not really clear who do you want to add flags on
> >> top of it?
> >>
> >> I am not really sure we really need a node aware interface for memcg.
> >> The global reclaim interface will likely need a different node because
> >> we do not want to make this CONFIG_MEMCG constrained.
> >
> > A nodemask argument for memory.reclaim can be useful for memory
> > tiering between NUMA nodes with different performance. Similar to
> > proactive reclaim, it can allow a userspace daemon to drive
> > memcg-based proactive demotion via the reclaim-based demotion
> > mechanism in the kernel.
>
> I am not sure whether nodemask is a good way for demoting pages between
> different types of memory. For example, for a system with DRAM and
> PMEM, if specifying DRAM node in nodemask means demoting to PMEM, what
> is the meaning of specifying PMEM node? reclaiming to disk?
>
> In general, I have no objection to the idea in general. But we should
> have a clear and consistent interface. Per my understanding the default
> memcg interface is for memory, regardless of memory types. The memory
> reclaiming means reduce the memory usage, regardless of memory types.
> We need to either extending the semantics of memory reclaiming (to
> include memory demoting too), or add another interface for memory
> demoting.
Good point. With the "demote pages during reclaim" patch series,
reclaim is already extended to demote pages as well. For example,
can_reclaim_anon_pages() returns true if demotion is allowed and
shrink_page_list() can demote pages instead of reclaiming pages.
Currently, demotion is disabled for memcg reclaim, which I think can
be relaxed and also necessary for memcg-based proactive demotion. I'd
like to suggest that we extend the semantics of memory.reclaim to
cover memory demotion as well. A flag can be used to enable/disable
the demotion behavior.
next prev parent reply other threads:[~2022-04-03 6:56 UTC|newest]
Thread overview: 61+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-03-31 8:41 [PATCH resend] memcg: introduce per-memcg reclaim interface Yosry Ahmed
2022-03-31 17:25 ` Roman Gushchin
2022-04-01 6:01 ` Wei Xu
2022-04-01 9:11 ` Yosry Ahmed
2022-04-01 18:39 ` Roman Gushchin
2022-04-01 21:13 ` Johannes Weiner
2022-04-01 21:21 ` Roman Gushchin
2022-04-01 21:38 ` Wei Xu
2022-04-01 21:51 ` Johannes Weiner
2022-04-04 17:14 ` Shakeel Butt
2022-04-04 17:13 ` Yosry Ahmed
2022-04-04 17:55 ` Roman Gushchin
2022-04-01 9:15 ` Yosry Ahmed
2022-04-01 15:41 ` Shakeel Butt
2022-04-01 13:49 ` Michal Hocko
2022-04-01 16:58 ` Roman Gushchin
2022-04-04 8:44 ` Michal Hocko
2022-04-04 18:25 ` Roman Gushchin
2022-03-31 19:25 ` Johannes Weiner
2022-04-01 0:33 ` Andrew Morton
2022-04-01 3:38 ` Wei Xu
2022-04-01 9:17 ` Yosry Ahmed
2022-04-01 13:03 ` Michal Hocko
2022-04-01 3:05 ` Chen Wandun
2022-04-01 9:20 ` Yosry Ahmed
2022-04-01 9:48 ` Chen Wandun
2022-04-01 10:02 ` Yosry Ahmed
2022-04-01 4:05 ` Wei Xu
2022-04-01 9:22 ` Yosry Ahmed
2022-04-01 15:22 ` Johannes Weiner
2022-04-01 20:14 ` Wei Xu
2022-04-01 21:07 ` Johannes Weiner
2022-04-04 17:08 ` Shakeel Butt
2022-04-05 2:30 ` Wei Xu
2022-04-05 10:09 ` Michal Koutný
2022-04-01 8:39 ` Vaibhav Jain
2022-04-01 9:23 ` Yosry Ahmed
2022-04-04 3:50 ` Vaibhav Jain
2022-04-04 17:18 ` Yosry Ahmed
2022-04-01 13:54 ` Michal Hocko
2022-04-01 16:56 ` Wei Xu
2022-04-02 8:13 ` Huang, Ying
2022-04-03 6:46 ` Wei Xu
2022-04-03 6:56 ` Wei Xu [this message]
2022-04-06 0:48 ` Huang, Ying
2022-04-06 1:07 ` Wei Xu
2022-04-06 2:49 ` Huang, Ying
2022-04-06 5:02 ` Wei Xu
2022-04-06 6:32 ` Huang, Ying
2022-04-06 7:05 ` Wei Xu
2022-04-06 8:49 ` Huang, Ying
2022-04-06 20:16 ` Wei Xu
2022-04-07 7:35 ` Michal Hocko
2022-04-07 21:26 ` Tim Chen
2022-04-07 22:07 ` Wei Xu
2022-04-07 22:12 ` Wei Xu
2022-04-07 23:11 ` Tim Chen
2022-04-08 2:10 ` Wei Xu
2022-04-08 3:08 ` Huang, Ying
2022-04-08 4:10 ` Wei Xu
2022-04-04 17:09 ` Yosry Ahmed
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