From: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
To: Christopher Lameter <cl@linux.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
linuxppc-dev@lists.ozlabs.org, linux-mm@kvack.org,
linux-kernel@vger.kernel.org, Michal Hocko <mhocko@suse.com>,
Mel Gorman <mgorman@suse.de>, Vlastimil Babka <vbabka@suse.cz>,
"Kirill A. Shutemov" <kirill@shutemov.name>,
Michael Ellerman <mpe@ellerman.id.au>,
Linus Torvalds <torvalds@linux-foundation.org>,
Gautham R Shenoy <ego@linux.vnet.ibm.com>,
Satheesh Rajendran <sathnaga@linux.vnet.ibm.com>,
David Hildenbrand <david@redhat.com>
Subject: Re: [PATCH v5 3/3] mm/page_alloc: Keep memoryless cpuless node 0 offline
Date: Tue, 30 Jun 2020 09:31:25 +0530 [thread overview]
Message-ID: <20200630040125.GA31617@linux.vnet.ibm.com> (raw)
In-Reply-To: <alpine.DEB.2.22.394.2006291456550.27163@www.lameter.com>
* Christopher Lameter <cl@linux.com> [2020-06-29 14:58:40]:
> On Wed, 24 Jun 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.
>
> Maybe add something to explain why you are not simply mapping the
> existing memory to NUMA node 0 which is after all just a numbering scheme
> used by the kernel and can be used arbitrarily?
>
I thought Michal Hocko already gave a clear picture on why mapping is a bad
idea. https://lore.kernel.org/lkml/20200316085425.GB11482@dhcp22.suse.cz/t/#u
Are you suggesting that we add that as part of the changelog?
> This could be seen more as a bug in the arch code during the setup of NUMA
> nodes. The two nodes are created by the firmwware / bootstrap code after
> all. Just do not do it?
>
- The arch/setup code in powerpc is not onlining these nodes.
- Later on cpus/memory in node 0 can be onlined.
- Firmware in this case Phyp is an independent code by itself.
--
Thanks and Regards
Srikar Dronamraju
WARNING: multiple messages have this Message-ID (diff)
From: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
To: Christopher Lameter <cl@linux.com>
Cc: Gautham R Shenoy <ego@linux.vnet.ibm.com>,
Michal Hocko <mhocko@suse.com>,
David Hildenbrand <david@redhat.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
Satheesh Rajendran <sathnaga@linux.vnet.ibm.com>,
Mel Gorman <mgorman@suse.de>,
"Kirill A. Shutemov" <kirill@shutemov.name>,
Andrew Morton <akpm@linux-foundation.org>,
linuxppc-dev@lists.ozlabs.org, Vlastimil Babka <vbabka@suse.cz>
Subject: Re: [PATCH v5 3/3] mm/page_alloc: Keep memoryless cpuless node 0 offline
Date: Tue, 30 Jun 2020 09:31:25 +0530 [thread overview]
Message-ID: <20200630040125.GA31617@linux.vnet.ibm.com> (raw)
In-Reply-To: <alpine.DEB.2.22.394.2006291456550.27163@www.lameter.com>
* Christopher Lameter <cl@linux.com> [2020-06-29 14:58:40]:
> On Wed, 24 Jun 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.
>
> Maybe add something to explain why you are not simply mapping the
> existing memory to NUMA node 0 which is after all just a numbering scheme
> used by the kernel and can be used arbitrarily?
>
I thought Michal Hocko already gave a clear picture on why mapping is a bad
idea. https://lore.kernel.org/lkml/20200316085425.GB11482@dhcp22.suse.cz/t/#u
Are you suggesting that we add that as part of the changelog?
> This could be seen more as a bug in the arch code during the setup of NUMA
> nodes. The two nodes are created by the firmwware / bootstrap code after
> all. Just do not do it?
>
- The arch/setup code in powerpc is not onlining these nodes.
- Later on cpus/memory in node 0 can be onlined.
- Firmware in this case Phyp is an independent code by itself.
--
Thanks and Regards
Srikar Dronamraju
next prev parent reply other threads:[~2020-06-30 4:01 UTC|newest]
Thread overview: 67+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-24 9:28 [PATCH v5 0/3] Offline memoryless cpuless node 0 Srikar Dronamraju
2020-06-24 9:28 ` Srikar Dronamraju
2020-06-24 9:28 ` [PATCH v5 1/3] powerpc/numa: Set numa_node for all possible cpus Srikar Dronamraju
2020-06-24 9:28 ` Srikar Dronamraju
2020-06-24 9:48 ` Gautham R Shenoy
2020-06-24 9:48 ` Gautham R Shenoy
2020-06-24 9:28 ` [PATCH v5 2/3] powerpc/numa: Prefer node id queried from vphn Srikar Dronamraju
2020-06-24 9:28 ` Srikar Dronamraju
2020-06-24 10:29 ` Gautham R Shenoy
2020-06-24 10:29 ` Gautham R Shenoy
2020-06-24 9:28 ` [PATCH v5 3/3] mm/page_alloc: Keep memoryless cpuless node 0 offline Srikar Dronamraju
2020-06-24 9:28 ` Srikar Dronamraju
2020-06-29 14:58 ` Christopher Lameter
2020-06-29 14:58 ` Christopher Lameter
2020-06-29 14:58 ` Christopher Lameter
2020-06-30 4:01 ` Srikar Dronamraju [this message]
2020-06-30 4:01 ` Srikar Dronamraju
2020-07-01 12:23 ` Michal Hocko
2020-07-01 12:23 ` Michal Hocko
2020-07-01 8:42 ` Michal Hocko
2020-07-01 8:42 ` Michal Hocko
2020-07-01 10:04 ` Srikar Dronamraju
2020-07-01 10:04 ` Srikar Dronamraju
2020-07-01 10:15 ` David Hildenbrand
2020-07-01 10:15 ` David Hildenbrand
2020-07-01 11:01 ` Srikar Dronamraju
2020-07-01 11:01 ` Srikar Dronamraju
2020-07-01 11:06 ` David Hildenbrand
2020-07-01 11:06 ` David Hildenbrand
2020-07-01 11:30 ` David Hildenbrand
2020-07-01 11:30 ` David Hildenbrand
2020-07-01 12:21 ` Michal Hocko
2020-07-01 12:21 ` Michal Hocko
2020-07-02 6:44 ` Srikar Dronamraju
2020-07-02 6:44 ` Srikar Dronamraju
2020-07-02 8:41 ` Michal Hocko
2020-07-02 8:41 ` Michal Hocko
2020-07-02 14:32 ` Srikar Dronamraju
2020-07-02 14:32 ` Srikar Dronamraju
2020-07-03 9:10 ` Michal Suchánek
2020-07-03 9:10 ` Michal Suchánek
2020-07-03 9:24 ` Michal Hocko
2020-07-03 9:24 ` Michal Hocko
2020-07-03 10:59 ` Michal Hocko
2020-07-03 10:59 ` Michal Hocko
2020-07-03 11:32 ` David Hildenbrand
2020-07-03 11:32 ` David Hildenbrand
2020-07-03 11:46 ` Michal Hocko
2020-07-03 11:46 ` Michal Hocko
2020-07-03 12:58 ` Srikar Dronamraju
2020-07-03 12:58 ` Srikar Dronamraju
2020-08-07 4:32 ` Andrew Morton
2020-08-07 4:32 ` Andrew Morton
2020-08-07 6:58 ` David Hildenbrand
2020-08-07 6:58 ` David Hildenbrand
2020-08-07 10:04 ` Michal Suchánek
2020-08-07 10:04 ` Michal Suchánek
2020-08-12 6:01 ` Srikar Dronamraju
2020-08-12 6:01 ` Srikar Dronamraju
2020-08-18 7:32 ` David Hildenbrand
2020-08-18 7:32 ` David Hildenbrand
2020-08-18 7:37 ` Michal Hocko
2020-08-18 7:37 ` Michal Hocko
2020-08-18 7:49 ` Srikar Dronamraju
2020-08-18 7:49 ` Srikar Dronamraju
2020-07-06 16:08 ` Andi Kleen
2020-07-06 16:08 ` Andi Kleen
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