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From: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Michal Hocko <mhocko@suse.com>,
	Srikar Dronamraju <srikar@linux.vnet.ibm.com>,
	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, Vlastimil Babka <vbabka@suse.cz>
Subject: [PATCH v2 0/3] Offline memoryless cpuless node 0
Date: Tue, 28 Apr 2020 15:08:33 +0530
Message-ID: <20200428093836.27190-1-srikar@linux.vnet.ibm.com> (raw)

Changelog v1:->v2:
- Rebased to v5.7-rc3
- Updated the changelog.

Linux kernel configured 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.

This can cause
1. numa_balancing to be enabled on systems with only one online node.
2. Existence of dummy (cpuless and memoryless) node which can confuse
users/scripts looking at output of lscpu / numactl.

This patchset wants to correct this anomaly.

This should only affect systems that have CONFIG_MEMORYLESS_NODES.
Currently there are only 2 architectures ia64 and powerpc that have this
config.

Note: Patch 3 in this patch series depends on patches 1 and 2.
Without patches 1 and 2, patch 3 might crash powerpc.

v5.7-rc3
 available: 2 nodes (0,2)
 node 0 cpus:
 node 0 size: 0 MB
 node 0 free: 0 MB
 node 2 cpus: 0 1 2 3 4 5 6 7
 node 2 size: 32625 MB
 node 2 free: 31490 MB
 node distances:
 node   0   2
   0:  10  20
   2:  20  10

proc and sys files
------------------
 /sys/devices/system/node/online:            0,2
 /proc/sys/kernel/numa_balancing:            1
 /sys/devices/system/node/has_cpu:           2
 /sys/devices/system/node/has_memory:        2
 /sys/devices/system/node/has_normal_memory: 2
 /sys/devices/system/node/possible:          0-31

v5.7-rc3 + patches
------------------
 available: 1 nodes (2)
 node 2 cpus: 0 1 2 3 4 5 6 7
 node 2 size: 32625 MB
 node 2 free: 31487 MB
 node distances:
 node   2
   2:  10

proc and sys files
------------------
/sys/devices/system/node/online:            2
/proc/sys/kernel/numa_balancing:            0
/sys/devices/system/node/has_cpu:           2
/sys/devices/system/node/has_memory:        2
/sys/devices/system/node/has_normal_memory: 2
/sys/devices/system/node/possible:          0-31

Cc: linuxppc-dev@lists.ozlabs.org
Cc: linux-mm@kvack.org
Cc: linux-kernel@vger.kernel.org
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: "Kirill A. Shutemov" <kirill@shutemov.name>
Cc: Christopher Lameter <cl@linux.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>

Srikar Dronamraju (3):
  powerpc/numa: Set numa_node for all possible cpus
  powerpc/numa: Prefer node id queried from vphn
  mm/page_alloc: Keep memoryless cpuless node 0 offline

 arch/powerpc/mm/numa.c | 32 ++++++++++++++++++++++----------
 mm/page_alloc.c        |  4 +++-
 2 files changed, 25 insertions(+), 11 deletions(-)

-- 
2.20.1


             reply index

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-04-28  9:38 Srikar Dronamraju [this message]
2020-04-28  9:38 ` [PATCH v2 1/3] powerpc/numa: Set numa_node for all possible cpus Srikar Dronamraju
2020-04-28  9:38 ` [PATCH v2 2/3] powerpc/numa: Prefer node id queried from vphn Srikar Dronamraju
2020-04-29  6:52   ` Gautham R Shenoy
2020-04-30  4:34     ` Srikar Dronamraju
2020-04-28  9:38 ` [PATCH v2 3/3] mm/page_alloc: Keep memoryless cpuless node 0 offline Srikar Dronamraju
2020-04-28 23:59   ` Andrew Morton
2020-04-29  1:41     ` Srikar Dronamraju
2020-04-29 12:22       ` Michal Hocko
2020-04-30  7:18         ` Srikar Dronamraju
2020-05-04  9:37           ` Michal Hocko
2020-05-08 13:03             ` Srikar Dronamraju
2020-05-08 13:39               ` David Hildenbrand
2020-05-08 13:42                 ` David Hildenbrand
2020-05-11 17:47                   ` Srikar Dronamraju
2020-05-12  7:49                     ` David Hildenbrand
2020-05-12 10:42                       ` Srikar Dronamraju

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