From: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
To: Michal Hocko <mhocko@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
Mel Gorman <mgorman@suse.de>,
"Kirill A. Shutemov" <kirill@shutemov.name>,
Christopher Lameter <cl@linux.com>,
linuxppc-dev@lists.ozlabs.org,
Andrew Morton <akpm@linux-foundation.org>,
Vlastimil Babka <vbabka@suse.cz>
Subject: Re: [PATCH 3/3] mm/page_alloc: Keep memoryless cpuless node 0 offline
Date: Wed, 18 Mar 2020 13:20:08 +0530 [thread overview]
Message-ID: <20200318075008.GE4879@linux.vnet.ibm.com> (raw)
In-Reply-To: <20200316085425.GB11482@dhcp22.suse.cz>
* Michal Hocko <mhocko@kernel.org> [2020-03-16 09:54:25]:
> On Sun 15-03-20 14:20:05, Cristopher Lameter wrote:
> > On Wed, 11 Mar 2020, Srikar Dronamraju wrote:
> >
> > > Currently Linux kernel with CONFIG_NUMA on a system with multiple
> > > possible nodes, marks node 0 as online at boot. However in practice,
> > > there are systems which have node 0 as memoryless and cpuless.
> >
> > Would it not be better and simpler to require that node 0 always has
> > memory (and processors)? A mininum operational set?
>
> I do not think you can simply ignore the reality. I cannot say that I am
> a fan of memoryless/cpuless numa configurations but they are a sad
> reality of different LPAR configurations. We have to deal with them.
> Besides that I do not really see any strong technical arguments to lack
> a support for those crippled configurations. We do have zonelists that
> allow to do reasonable decisions on memoryless nodes. So no, I do not
> think that this is a viable approach.
>
I agree with Michal, kernel should accept the reality and work with
different Lpar configurations.
> > We can dynamically number the nodes right? So just make sure that the
> > firmware properly creates memory on node 0?
>
> Are you suggesting that the OS would renumber NUMA nodes coming
> from FW just to satisfy node 0 existence? If yes then I believe this is
> really a bad idea because it would make HW/LPAR configuration matching
> to the resulting memory layout really hard to follow.
>
> --
> Michal Hocko
> SUSE Labs
Michal, Vlastimil, Christoph and others, do you have any more comments,
suggestions or any other feedback. If not, can you please add your
reviewed-by, acked etc.
--
Thanks and Regards
Srikar Dronamraju
WARNING: multiple messages have this Message-ID (diff)
From: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
To: Michal Hocko <mhocko@kernel.org>
Cc: Christopher Lameter <cl@linux.com>,
Andrew Morton <akpm@linux-foundation.org>,
Michael Ellerman <mpe@ellerman.id.au>,
linuxppc-dev@lists.ozlabs.org, linux-mm@kvack.org,
linux-kernel@vger.kernel.org, Mel Gorman <mgorman@suse.de>,
Vlastimil Babka <vbabka@suse.cz>,
"Kirill A. Shutemov" <kirill@shutemov.name>,
Linus Torvalds <torvalds@linux-foundation.org>
Subject: Re: [PATCH 3/3] mm/page_alloc: Keep memoryless cpuless node 0 offline
Date: Wed, 18 Mar 2020 13:20:08 +0530 [thread overview]
Message-ID: <20200318075008.GE4879@linux.vnet.ibm.com> (raw)
In-Reply-To: <20200316085425.GB11482@dhcp22.suse.cz>
* Michal Hocko <mhocko@kernel.org> [2020-03-16 09:54:25]:
> On Sun 15-03-20 14:20:05, Cristopher Lameter wrote:
> > On Wed, 11 Mar 2020, Srikar Dronamraju wrote:
> >
> > > Currently Linux kernel with CONFIG_NUMA on a system with multiple
> > > possible nodes, marks node 0 as online at boot. However in practice,
> > > there are systems which have node 0 as memoryless and cpuless.
> >
> > Would it not be better and simpler to require that node 0 always has
> > memory (and processors)? A mininum operational set?
>
> I do not think you can simply ignore the reality. I cannot say that I am
> a fan of memoryless/cpuless numa configurations but they are a sad
> reality of different LPAR configurations. We have to deal with them.
> Besides that I do not really see any strong technical arguments to lack
> a support for those crippled configurations. We do have zonelists that
> allow to do reasonable decisions on memoryless nodes. So no, I do not
> think that this is a viable approach.
>
I agree with Michal, kernel should accept the reality and work with
different Lpar configurations.
> > We can dynamically number the nodes right? So just make sure that the
> > firmware properly creates memory on node 0?
>
> Are you suggesting that the OS would renumber NUMA nodes coming
> from FW just to satisfy node 0 existence? If yes then I believe this is
> really a bad idea because it would make HW/LPAR configuration matching
> to the resulting memory layout really hard to follow.
>
> --
> Michal Hocko
> SUSE Labs
Michal, Vlastimil, Christoph and others, do you have any more comments,
suggestions or any other feedback. If not, can you please add your
reviewed-by, acked etc.
--
Thanks and Regards
Srikar Dronamraju
next prev parent reply other threads:[~2020-03-18 7:51 UTC|newest]
Thread overview: 48+ 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 ` Srikar Dronamraju
2020-03-11 11:02 ` [PATCH 1/3] powerpc/numa: Set numa_node for all possible cpus Srikar Dronamraju
2020-03-11 11:02 ` Srikar Dronamraju
2020-03-11 11:57 ` Michal Hocko
2020-03-11 11:57 ` Michal Hocko
2020-03-12 5:27 ` Srikar Dronamraju
2020-03-12 5:27 ` Srikar Dronamraju
2020-03-12 8:23 ` Sachin Sant
2020-03-12 8:23 ` Sachin Sant
2020-03-12 9:30 ` Vlastimil Babka
2020-03-12 9:30 ` Vlastimil Babka
2020-03-12 13:14 ` Srikar Dronamraju
2020-03-12 13:14 ` Srikar Dronamraju
2020-03-12 13:51 ` Vlastimil Babka
2020-03-12 13:51 ` Vlastimil Babka
2020-03-12 16:13 ` Srikar Dronamraju
2020-03-12 16:13 ` Srikar Dronamraju
2020-03-12 16:41 ` Vlastimil Babka
2020-03-12 16:41 ` Vlastimil Babka
2020-03-13 9:47 ` Joonsoo Kim
2020-03-13 9:47 ` Joonsoo Kim
2020-03-13 11:04 ` Srikar Dronamraju
2020-03-13 11:04 ` Srikar Dronamraju
2020-03-13 11:38 ` Vlastimil Babka
2020-03-13 11:38 ` Vlastimil Babka
2020-03-16 8:15 ` Joonsoo Kim
2020-03-16 8:15 ` Joonsoo Kim
2020-03-13 11:22 ` Srikar Dronamraju
2020-03-13 11:22 ` Srikar Dronamraju
2020-03-16 9:06 ` Michal Hocko
2020-03-16 9:06 ` Michal Hocko
2020-03-17 13:44 ` Vlastimil Babka
2020-03-17 13:44 ` Vlastimil Babka
2020-03-17 14:01 ` Michal Hocko
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 ` Srikar Dronamraju
2020-03-11 11:02 ` [PATCH 3/3] mm/page_alloc: Keep memoryless cpuless node 0 offline Srikar Dronamraju
2020-03-11 11:02 ` Srikar Dronamraju
2020-03-15 14:20 ` Christopher Lameter
2020-03-15 14:20 ` Christopher Lameter
2020-03-16 8:54 ` Michal Hocko
2020-03-16 8:54 ` Michal Hocko
2020-03-18 7:50 ` Srikar Dronamraju [this message]
2020-03-18 7:50 ` Srikar Dronamraju
2020-03-18 18:57 ` Christopher Lameter
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=20200318075008.GE4879@linux.vnet.ibm.com \
--to=srikar@linux.vnet.ibm.com \
--cc=akpm@linux-foundation.org \
--cc=cl@linux.com \
--cc=kirill@shutemov.name \
--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=torvalds@linux-foundation.org \
--cc=vbabka@suse.cz \
/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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.