From: osalvador@suse.de
To: Dave Hansen <dave.hansen@linux.intel.com>
Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org,
yang.shi@linux.alibaba.com, rientjes@google.com,
ying.huang@intel.com, dan.j.williams@intel.com, david@redhat.com
Subject: Re: [RFC][PATCH 3/9] mm/migrate: update migration order during on hotplug events
Date: Wed, 07 Oct 2020 20:08:10 +0200 [thread overview]
Message-ID: <8acf3637996d5c72709a3143f41165f8@suse.de> (raw)
In-Reply-To: <20201007161741.DDC85648@viggo.jf.intel.com>
On 2020-10-07 18:17, Dave Hansen wrote:
> From: Dave Hansen <dave.hansen@linux.intel.com>
>
> Reclaim-based migration is attempting to optimize data placement in
> memory based on the system topology. If the system changes, so must
> the migration ordering.
>
> The implementation here is pretty simple and entirely unoptimized. On
> any memory or CPU hotplug events, assume that a node was added or
> removed and recalculate all migration targets. This ensures that the
> node_demotion[] array is always ready to be used in case the new
> reclaim mode is enabled.
>
> This recalculation is far from optimal, most glaringly that it does
> not even attempt to figure out if nodes are actually coming or going.
> But, given the expected paucity of hotplug events, this should be
> fine.
Hi Dave,
I am still going through all the details, but just wanted to comment
early on this one.
Could not you hook into __try_online_node/try_offline_node?
In there we check whether a node should be brought up or removed due to
lack of cpus and memory.
That is being checked during hot-remove operations.
We also have node_states_check_changes_{offline,online} and their pair
node_states_{set,clear}_node, that checks during online/offline stages
which states should be removed from the node, but that is only wrt.
memory (I guess we would only be interested in N_MEMORY).
Thanks
next prev parent reply other threads:[~2020-10-07 18:08 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-07 16:17 [RFC][PATCH 0/9] [v4][RESEND] Migrate Pages in lieu of discard Dave Hansen
2020-10-07 16:17 ` [RFC][PATCH 1/9] mm/numa: node demotion data structure and lookup Dave Hansen
2020-10-07 16:17 ` [RFC][PATCH 2/9] mm/numa: automatically generate node migration order Dave Hansen
2020-10-07 16:17 ` [RFC][PATCH 3/9] mm/migrate: update migration order during on hotplug events Dave Hansen
2020-10-07 18:08 ` osalvador [this message]
2020-10-07 16:17 ` [RFC][PATCH 4/9] mm/migrate: make migrate_pages() return nr_succeeded Dave Hansen
2020-10-07 16:17 ` [RFC][PATCH 5/9] mm/migrate: demote pages during reclaim Dave Hansen
2020-10-27 15:29 ` Oscar Salvador
2020-10-27 16:53 ` Yang Shi
2020-10-07 16:17 ` [RFC][PATCH 6/9] mm/vmscan: add page demotion counter Dave Hansen
2020-10-19 7:37 ` Huang, Ying
2020-10-27 16:41 ` Yang Shi
2020-10-28 1:25 ` Huang, Ying
2020-10-07 16:17 ` [RFC][PATCH 7/9] mm/vmscan: Consider anonymous pages without swap Dave Hansen
2020-10-29 8:14 ` Oscar Salvador
2020-10-29 14:33 ` Dave Hansen
2020-10-29 15:57 ` Yang Shi
2020-10-29 19:08 ` osalvador
2020-10-29 19:30 ` Yang Shi
2020-10-07 16:17 ` [RFC][PATCH 8/9] mm/vmscan: never demote for memcg reclaim Dave Hansen
2020-10-07 16:17 ` [RFC][PATCH 9/9] mm/migrate: new zone_reclaim_mode to enable reclaim migration Dave Hansen
2020-10-12 21:30 ` [RFC][PATCH 0/9] [v4][RESEND] Migrate Pages in lieu of discard Yang Shi
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