From: Jiang Liu <jiang.liu@linux.intel.com>
To: Kamezawa Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>,
Andrew Morton <akpm@linux-foundation.org>,
David Rientjes <rientjes@google.com>
Cc: "Patil, Kiran" <kiran.patil@intel.com>,
Mel Gorman <mgorman@suse.de>,
Mike Galbraith <umgwanakikbuti@gmail.com>,
Peter Zijlstra <peterz@infradead.org>,
"Wysocki, Rafael J" <rafael.j.wysocki@intel.com>,
Tang Chen <tangchen@cn.fujitsu.com>, Tejun Heo <tj@kernel.org>,
"Kirsher, Jeffrey T" <jeffrey.t.kirsher@intel.com>,
"Brandeburg, Jesse" <jesse.brandeburg@intel.com>,
"Nelson, Shannon" <shannon.nelson@intel.com>,
"Wyborny, Carolyn" <carolyn.wyborny@intel.com>,
"Skidmore, Donald C" <donald.c.skidmore@intel.com>,
"Vick, Matthew" <matthew.vick@intel.com>,
"Ronciak, John" <john.ronciak@intel.com>,
"Williams, Mitch A" <mitch.a.williams@intel.com>,
"Luck, Tony" <tony.luck@intel.com>,
"netdev@vger.kernel.org" <netdev@vger.kernel.org>,
"x86@kernel.org" <x86@kernel.org>,
"linux-hotplug@vger.kernel.org" <linux-hotplug@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"linux-mm@kvack.org" <linux-mm@kvack.org>,
"intel-wired-lan@lists.osuosl.org"
<intel-wired-lan@lists.osuosl.org>
Subject: Re: [Intel-wired-lan] [Patch V3 5/9] i40e: Use numa_mem_id() to better support memoryless node
Date: Fri, 09 Oct 2015 09:25:36 +0000 [thread overview]
Message-ID: <56178810.8040200@linux.intel.com> (raw)
In-Reply-To: <56178419.6090503@jp.fujitsu.com>
On 2015/10/9 17:08, Kamezawa Hiroyuki wrote:
> On 2015/10/09 14:52, Jiang Liu wrote:
>> On 2015/10/9 4:20, Andrew Morton wrote:
>>> On Wed, 19 Aug 2015 17:18:15 -0700 (PDT) David Rientjes
>>> <rientjes@google.com> wrote:
>>>
>>>> On Wed, 19 Aug 2015, Patil, Kiran wrote:
>>>>
>>>>> Acked-by: Kiran Patil <kiran.patil@intel.com>
>>>>
>>>> Where's the call to preempt_disable() to prevent kernels with
>>>> preemption
>>>> from making numa_node_id() invalid during this iteration?
>>>
>>> David asked this question twice, received no answer and now the patch
>>> is in the maintainer tree, destined for mainline.
>>>
>>> If I was asked this question I would respond
>>>
>>> The use of numa_mem_id() is racy and best-effort. If the unlikely
>>> race occurs, the memory allocation will occur on the wrong node, the
>>> overall result being very slightly suboptimal performance. The
>>> existing use of numa_node_id() suffers from the same issue.
>>>
>>> But I'm not the person proposing the patch. Please don't just ignore
>>> reviewer comments!
>> Hi Andrew,
>> Apologize for the slow response due to personal reasons!
>> And thanks for answering the question from David. To be honest,
>> I didn't know how to answer this question before. Actually this
>> question has puzzled me for a long time when dealing with memory
>> hot-removal. For normal cases, it only causes sub-optimal memory
>> allocation if schedule event happens between querying NUMA node id
>> and calling alloc_pages_node(). But what happens if system run into
>> following execution sequence?
>> 1) node = numa_mem_id();
>> 2) memory hot-removal event triggers
>> 2.1) remove affected memory
>> 2.2) reset pgdat to zero if node becomes empty after memory removal
>
> I'm sorry if I misunderstand something.
> After commit b0dc3a342af36f95a68fe229b8f0f73552c5ca08, there is no
> memset().
Hi Kamezawa,
Thanks for the information. The commit solved the issue what
I was puzzling about. With this change applied, thing should work
as expected. Seems it would be better to enhance __build_all_zonelists()
to handle those offlined empty nodes too, but that really doesn't
make to much difference:)
Thanks for the info again!
Thanks!
Gerry
next prev parent reply other threads:[~2015-10-09 9:25 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-08-17 3:18 [Patch V3 0/9] Enable memoryless node support for x86 Jiang Liu
2015-08-17 3:18 ` [Patch V3 1/9] x86, NUMA, ACPI: Online node earlier when doing CPU hot-addition Jiang Liu
2015-08-17 3:18 ` [Patch V3 2/9] kernel/profile.c: Replace cpu_to_mem() with cpu_to_node() Jiang Liu
2015-08-18 0:31 ` David Rientjes
2015-08-19 7:18 ` Jiang Liu
2015-08-20 0:00 ` David Rientjes
2015-10-09 2:35 ` Jiang Liu
2015-08-17 3:19 ` [Patch V3 3/9] sgi-xp: Replace cpu_to_node() with cpu_to_mem() to support memoryless node Jiang Liu
2015-08-18 0:25 ` David Rientjes
2015-08-19 8:20 ` Jiang Liu
2015-08-20 0:02 ` David Rientjes
2015-08-20 6:36 ` Jiang Liu
2015-10-09 5:04 ` Jiang Liu
2015-08-19 11:52 ` Robin Holt
2015-08-19 12:45 ` Jiang Liu
2015-08-17 3:19 ` [Patch V3 4/9] openvswitch: " Jiang Liu
2015-08-18 0:14 ` Pravin Shelar
2015-08-17 3:19 ` [Patch V3 5/9] i40e: Use numa_mem_id() to better " Jiang Liu
2015-08-18 0:35 ` David Rientjes
2015-08-19 22:38 ` [Intel-wired-lan] " Patil, Kiran
2015-08-20 0:18 ` David Rientjes
2015-10-08 20:20 ` Andrew Morton
2015-10-09 5:52 ` Jiang Liu
2015-10-09 9:08 ` Kamezawa Hiroyuki
2015-10-09 9:25 ` Jiang Liu [this message]
2015-08-17 3:19 ` [Patch V3 6/9] i40evf: " Jiang Liu
2015-08-17 19:03 ` [Intel-wired-lan] " Patil, Kiran
2015-08-17 3:19 ` [Patch V3 7/9] x86, numa: Kill useless code to improve code readability Jiang Liu
2015-08-17 3:19 ` [Patch V3 8/9] mm: Update _mem_id_[] for every possible CPU when memory configuration changes Jiang Liu
2015-08-17 3:19 ` [Patch V3 9/9] mm, x86: Enable memoryless node support to better support CPU/memory hotplug Jiang Liu
2015-08-18 6:11 ` Tang Chen
[not found] ` <55D2D7C2.3090109@linux.intel.com>
2015-08-18 11:28 ` Tang Chen
2015-08-18 7:31 ` Ingo Molnar
2015-08-17 21:35 ` [Patch V3 0/9] Enable memoryless node support for x86 Andrew Morton
2015-08-18 10:02 ` Tang Chen
2015-08-19 8:09 ` Jiang Liu
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=56178810.8040200@linux.intel.com \
--to=jiang.liu@linux.intel.com \
--cc=akpm@linux-foundation.org \
--cc=carolyn.wyborny@intel.com \
--cc=donald.c.skidmore@intel.com \
--cc=intel-wired-lan@lists.osuosl.org \
--cc=jeffrey.t.kirsher@intel.com \
--cc=jesse.brandeburg@intel.com \
--cc=john.ronciak@intel.com \
--cc=kamezawa.hiroyu@jp.fujitsu.com \
--cc=kiran.patil@intel.com \
--cc=linux-hotplug@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=matthew.vick@intel.com \
--cc=mgorman@suse.de \
--cc=mitch.a.williams@intel.com \
--cc=netdev@vger.kernel.org \
--cc=peterz@infradead.org \
--cc=rafael.j.wysocki@intel.com \
--cc=rientjes@google.com \
--cc=shannon.nelson@intel.com \
--cc=tangchen@cn.fujitsu.com \
--cc=tj@kernel.org \
--cc=tony.luck@intel.com \
--cc=umgwanakikbuti@gmail.com \
--cc=x86@kernel.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 read-only IMAP folder(s) and NNTP newsgroup(s).