From: Wei Xu <weixugc@google.com>
To: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Linux MM <linux-mm@kvack.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Yang Shi <shy828301@gmail.com>,
David Rientjes <rientjes@google.com>,
Huang Ying <ying.huang@intel.com>,
Dan Williams <dan.j.williams@intel.com>,
David Hildenbrand <david@redhat.com>,
Oscar Salvador <osalvador@suse.de>
Subject: Re: [PATCH 02/10] mm/numa: automatically generate node migration order
Date: Fri, 9 Apr 2021 20:07:08 -0700 [thread overview]
Message-ID: <CAAPL-u8Jk-i-9-iSnU7_nb-k2ZMqdRk5c88d-M6Bi1rfv4kSLQ@mail.gmail.com> (raw)
In-Reply-To: <20210401183219.DC1928FA@viggo.jf.intel.com>
On Thu, Apr 1, 2021 at 11:35 AM Dave Hansen <dave.hansen@linux.intel.com> wrote:
> +/*
> + * node_demotion[] example:
> + *
> + * Consider a system with two sockets. Each socket has
> + * three classes of memory attached: fast, medium and slow.
> + * Each memory class is placed in its own NUMA node. The
> + * CPUs are placed in the node with the "fast" memory. The
> + * 6 NUMA nodes (0-5) might be split among the sockets like
> + * this:
> + *
> + * Socket A: 0, 1, 2
> + * Socket B: 3, 4, 5
> + *
> + * When Node 0 fills up, its memory should be migrated to
> + * Node 1. When Node 1 fills up, it should be migrated to
> + * Node 2. The migration path start on the nodes with the
> + * processors (since allocations default to this node) and
> + * fast memory, progress through medium and end with the
> + * slow memory:
> + *
> + * 0 -> 1 -> 2 -> stop
> + * 3 -> 4 -> 5 -> stop
> + *
> + * This is represented in the node_demotion[] like this:
> + *
> + * { 1, // Node 0 migrates to 1
> + * 2, // Node 1 migrates to 2
> + * -1, // Node 2 does not migrate
> + * 4, // Node 3 migrates to 4
> + * 5, // Node 4 migrates to 5
> + * -1} // Node 5 does not migrate
> + */
In this example, if we want to support multiple nodes as the demotion
target of a source node, we can group these nodes into three tiers
(classes):
fast class:
0 -> {1, 4} // 1 is the preferred
3 -> {4, 1} // 4 is the preferred
medium class:
1 -> {2, 5} // 2 is the preferred
4 -> {5, 2} // 5 is the preferred
slow class:
2 -> stop
5 -> stop
This can guarantee there are no cycles, either. Does it sound sensible?
> +again:
> + this_pass = next_pass;
> + next_pass = NODE_MASK_NONE;
> + /*
> + * To avoid cycles in the migration "graph", ensure
> + * that migration sources are not future targets by
> + * setting them in 'used_targets'. Do this only
> + * once per pass so that multiple source nodes can
> + * share a target node.
> + *
> + * 'used_targets' will become unavailable in future
> + * passes. This limits some opportunities for
> + * multiple source nodes to share a destination.
> + */
> + nodes_or(used_targets, used_targets, this_pass);
> + for_each_node_mask(node, this_pass) {
> + int target_node = establish_migrate_target(node, &used_targets);
> +
> + if (target_node == NUMA_NO_NODE)
> + continue;
> +
> + /* Visit targets from this pass in the next pass: */
> + node_set(target_node, next_pass);
> + }
> + /* Is another pass necessary? */
> + if (!nodes_empty(next_pass))
> + goto again;
This goto seems like exactly a "do {} while" loop. Any particular reason not to
use "do {} while" here?
next prev parent reply other threads:[~2021-04-10 3:07 UTC|newest]
Thread overview: 64+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-01 18:32 [PATCH 00/10] [v7][RESEND] Migrate Pages in lieu of discard Dave Hansen
2021-04-01 18:32 ` [PATCH 01/10] mm/numa: node demotion data structure and lookup Dave Hansen
2021-04-08 8:03 ` Oscar Salvador
2021-04-08 21:29 ` Dave Hansen
2021-04-09 5:32 ` Wei Xu
2021-04-01 18:32 ` [PATCH 02/10] mm/numa: automatically generate node migration order Dave Hansen
2021-04-08 8:26 ` Oscar Salvador
2021-04-08 21:51 ` Dave Hansen
2021-04-09 8:17 ` Oscar Salvador
2021-04-10 3:07 ` Wei Xu [this message]
2021-04-14 8:08 ` Oscar Salvador
2021-04-14 8:11 ` Oscar Salvador
2021-04-14 8:12 ` David Hildenbrand
2021-04-14 8:14 ` Oscar Salvador
2021-04-14 8:20 ` David Hildenbrand
2021-04-15 4:07 ` Wei Xu
2021-04-15 15:35 ` Dave Hansen
2021-04-15 20:25 ` Wei Xu
2021-04-01 18:32 ` [PATCH 03/10] mm/migrate: update node demotion order during on hotplug events Dave Hansen
2021-04-08 9:52 ` Oscar Salvador
2021-04-09 10:14 ` Oscar Salvador
2021-04-09 10:15 ` Oscar Salvador
2021-04-09 18:59 ` David Hildenbrand
2021-04-12 7:19 ` Oscar Salvador
2021-04-12 9:19 ` David Hildenbrand
2021-04-01 18:32 ` [PATCH 04/10] mm/migrate: make migrate_pages() return nr_succeeded Dave Hansen
2021-04-01 22:35 ` Wei Xu
2021-04-01 23:21 ` Dave Hansen
2021-04-01 22:39 ` Wei Xu
2021-04-08 10:14 ` Oscar Salvador
2021-04-08 17:26 ` Yang Shi
2021-04-08 18:17 ` Oscar Salvador
2021-04-08 18:21 ` Oscar Salvador
2021-04-08 20:40 ` Yang Shi
2021-04-09 5:06 ` Oscar Salvador
2021-04-09 5:43 ` Wei Xu
2021-04-09 15:43 ` Yang Shi
2021-04-09 15:50 ` Dave Hansen
2021-04-09 18:47 ` Wei Xu
2021-04-09 20:10 ` Yang Shi
2021-04-01 18:32 ` [PATCH 05/10] mm/migrate: demote pages during reclaim Dave Hansen
2021-04-01 20:01 ` Yang Shi
2021-04-01 22:58 ` Dave Hansen
2021-04-08 10:47 ` Oscar Salvador
2021-04-10 3:35 ` Wei Xu
2021-04-01 18:32 ` [PATCH 06/10] mm/vmscan: add page demotion counter Dave Hansen
2021-04-10 3:40 ` Wei Xu
2021-04-01 18:32 ` [PATCH 07/10] mm/vmscan: add helper for querying ability to age anonymous pages Dave Hansen
2021-04-07 18:40 ` Wei Xu
2021-04-09 8:31 ` Oscar Salvador
2021-04-01 18:32 ` [PATCH 08/10] mm/vmscan: Consider anonymous pages without swap Dave Hansen
2021-04-02 0:55 ` Wei Xu
2021-04-01 18:32 ` [PATCH 09/10] mm/vmscan: never demote for memcg reclaim Dave Hansen
2021-04-02 0:18 ` Wei Xu
2021-04-01 18:32 ` [PATCH 10/10] mm/migrate: new zone_reclaim_mode to enable reclaim migration Dave Hansen
2021-04-01 20:06 ` Yang Shi
2021-04-10 4:10 ` Wei Xu
2021-04-16 12:35 ` [PATCH 00/10] [v7][RESEND] Migrate Pages in lieu of discard Michal Hocko
2021-04-16 14:26 ` Dave Hansen
2021-04-16 15:02 ` Michal Hocko
2021-04-21 2:39 ` Huang, Ying
2021-05-07 6:14 ` Huang, Ying
-- strict thread matches above, loose matches on Subject: below --
2021-03-04 23:59 [PATCH 00/10] [v6] " Dave Hansen
2021-03-04 23:59 ` [PATCH 02/10] mm/numa: automatically generate node migration order Dave Hansen
2021-03-08 23:59 ` Yang Shi
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