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Message-Id: <20200428093836.27190-1-srikar@linux.vnet.ibm.com>
Date: Tue, 28 Apr 2020 15:08:33 +0530
From: Srikar Dronamraju <srikar@...ux.vnet.ibm.com>
To: Andrew Morton <akpm@...ux-foundation.org>
Cc: Srikar Dronamraju <srikar@...ux.vnet.ibm.com>,
linuxppc-dev@...ts.ozlabs.org, linux-mm@...ck.org,
linux-kernel@...r.kernel.org, Michal Hocko <mhocko@...e.com>,
Mel Gorman <mgorman@...e.de>, Vlastimil Babka <vbabka@...e.cz>,
"Kirill A. Shutemov" <kirill@...temov.name>,
Christopher Lameter <cl@...ux.com>,
Michael Ellerman <mpe@...erman.id.au>,
Linus Torvalds <torvalds@...ux-foundation.org>
Subject: [PATCH v2 0/3] Offline memoryless cpuless node 0
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@...ts.ozlabs.org
Cc: linux-mm@...ck.org
Cc: linux-kernel@...r.kernel.org
Cc: Michal Hocko <mhocko@...e.com>
Cc: Mel Gorman <mgorman@...e.de>
Cc: Vlastimil Babka <vbabka@...e.cz>
Cc: "Kirill A. Shutemov" <kirill@...temov.name>
Cc: Christopher Lameter <cl@...ux.com>
Cc: Michael Ellerman <mpe@...erman.id.au>
Cc: Andrew Morton <akpm@...ux-foundation.org>
Cc: Linus Torvalds <torvalds@...ux-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
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