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 7:50 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
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 [this message]
2020-03-18 18:57 ` Christopher Lameter
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