From: Vlastimil Babka <vbabka@suse.cz>
To: Michal Hocko <mhocko@kernel.org>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>,
Sachin Sant <sachinp@linux.vnet.ibm.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
LKML <linux-kernel@vger.kernel.org>,
linux-mm@kvack.org, Mel Gorman <mgorman@suse.de>,
"Kirill A. Shutemov" <kirill@shutemov.name>,
Andrew Morton <akpm@linux-foundation.org>,
linuxppc-dev@lists.ozlabs.org, Christopher Lameter <cl@linux.com>,
Joonsoo Kim <iamjoonsoo.kim@lge.com>,
Kirill Tkhai <ktkhai@virtuozzo.com>
Subject: Re: [PATCH 1/3] powerpc/numa: Set numa_node for all possible cpus
Date: Tue, 17 Mar 2020 14:44:45 +0100 [thread overview]
Message-ID: <65b99db6-3bdf-6caa-74e5-6d6b681f16b5@suse.cz> (raw)
In-Reply-To: <20200316090652.GC11482@dhcp22.suse.cz>
On 3/16/20 10:06 AM, Michal Hocko wrote:
> On Thu 12-03-20 17:41:58, Vlastimil Babka wrote:
> [...]
>> with nid present in:
>> N_POSSIBLE - pgdat might not exist, node_to_mem_node() must return some online
>
> I would rather have a dummy pgdat for those. Have a look at
> $ git grep "NODE_DATA.*->" | wc -l
> 63
>
> Who knows how many else we have there. I haven't looked more closely.
> Besides that what is a real reason to not have pgdat ther and force all
> users of a $random node from those that the platform considers possible
> for special casing? Is that a memory overhead? Is that really a thing?
I guess we can ignore memory overhead. I guess there only might be some concern
that for nodes that are initially offline, we will allocate the pgdat on a
different node, and after they are online, it will stay on a different node with
more access latency from local cpus. If we only allocate for online nodes, it
can always be local? But I guess it doesn't matter that much.
> Somebody has suggested to tweak some of the low level routines to do the
> special casing but I really have to say I do not like that. We shouldn't
> use the first online node or anything like that. We should simply always
> follow the topology presented by FW and of that we need to have a pgdat.
>
next prev parent reply other threads:[~2020-03-17 13:44 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-11 11:02 [PATCH 0/3] Offline memoryless cpuless node 0 Srikar Dronamraju
2020-03-11 11:02 ` [PATCH 1/3] powerpc/numa: Set numa_node for all possible cpus Srikar Dronamraju
2020-03-11 11:57 ` Michal Hocko
2020-03-12 5:27 ` Srikar Dronamraju
2020-03-12 8:23 ` Sachin Sant
2020-03-12 9:30 ` Vlastimil Babka
2020-03-12 13:14 ` Srikar Dronamraju
2020-03-12 13:51 ` Vlastimil Babka
2020-03-12 16:13 ` Srikar Dronamraju
2020-03-12 16:41 ` Vlastimil Babka
2020-03-13 9:47 ` Joonsoo Kim
2020-03-13 11:04 ` Srikar Dronamraju
2020-03-13 11:38 ` Vlastimil Babka
2020-03-16 8:15 ` Joonsoo Kim
2020-03-13 11:22 ` Srikar Dronamraju
2020-03-16 9:06 ` Michal Hocko
2020-03-17 13:44 ` Vlastimil Babka [this message]
2020-03-17 14:01 ` Michal Hocko
2020-03-11 11:02 ` [PATCH 2/3] powerpc/numa: Prefer node id queried from vphn Srikar Dronamraju
2020-03-11 11:02 ` [PATCH 3/3] mm/page_alloc: Keep memoryless cpuless node 0 offline Srikar Dronamraju
2020-03-15 14:20 ` Christopher Lameter
2020-03-16 8:54 ` Michal Hocko
2020-03-18 7:50 ` Srikar Dronamraju
2020-03-18 18:57 ` Christopher Lameter
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=65b99db6-3bdf-6caa-74e5-6d6b681f16b5@suse.cz \
--to=vbabka@suse.cz \
--cc=akpm@linux-foundation.org \
--cc=cl@linux.com \
--cc=iamjoonsoo.kim@lge.com \
--cc=kirill@shutemov.name \
--cc=ktkhai@virtuozzo.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=linuxppc-dev@lists.ozlabs.org \
--cc=mgorman@suse.de \
--cc=mhocko@kernel.org \
--cc=sachinp@linux.vnet.ibm.com \
--cc=srikar@linux.vnet.ibm.com \
--cc=torvalds@linux-foundation.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).