Commit ad2c8144418c6a81cefe65379fd47bbe8344cef2
Committed by
Linus Torvalds
Linus Torvalds
1 parent
c9e16131d6
Exists in
ti-lsk-linux-4.1.y
and in
10 other branches
topology: add support for node_to_mem_node() to determine the fallback node
Anton noticed (http://www.spinics.net/lists/linux-mm/msg67489.html) that
on ppc LPARs with memoryless nodes, a large amount of memory was consumed
by slabs and was marked unreclaimable. He tracked it down to slab
deactivations in the SLUB core when we allocate remotely, leading to poor
efficiency always when memoryless nodes are present.
After much discussion, Joonsoo provided a few patches that help
significantly. They don't resolve the problem altogether:
- memory hotplug still needs testing, that is when a memoryless node
becomes memory-ful, we want to dtrt
- there are other reasons for going off-node than memoryless nodes,
e.g., fully exhausted local nodes
Neither case is resolved with this series, but I don't think that should
block their acceptance, as they can be explored/resolved with follow-on
patches.
The series consists of:
[1/3] topology: add support for node_to_mem_node() to determine the
fallback node
[2/3] slub: fallback to node_to_mem_node() node if allocating on
memoryless node
- Joonsoo's patches to cache the nearest node with memory for each
NUMA node
[3/3] Partial revert of 81c98869faa5 (""kthread: ensure locality of
task_struct allocations")
- At Tejun's request, keep the knowledge of memoryless node fallback
to the allocator core.
This patch (of 3):
We need to determine the fallback node in slub allocator if the allocation
target node is memoryless node. Without it, the SLUB wrongly select the
node which has no memory and can't use a partial slab, because of node
mismatch. Introduced function, node_to_mem_node(X), will return a node Y
with memory that has the nearest distance. If X is memoryless node, it
will return nearest distance node, but, if X is normal node, it will
return itself.
We will use this function in following patch to determine the fallback
node.
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Nishanth Aravamudan <nacc@linux.vnet.ibm.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Han Pingtian <hanpt@linux.vnet.ibm.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Anton Blanchard <anton@samba.org>
Cc: Christoph Lameter <cl@linux.com>
Cc: Wanpeng Li <liwanp@linux.vnet.ibm.com>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Showing 2 changed files with 18 additions and 0 deletions Side-by-side Diff
include/linux/topology.h
| ... | ... | @@ -119,14 +119,23 @@ |
| 119 | 119 | * Use the accessor functions set_numa_mem(), numa_mem_id() and cpu_to_mem(). |
| 120 | 120 | */ |
| 121 | 121 | DECLARE_PER_CPU(int, _numa_mem_); |
| 122 | +extern int _node_numa_mem_[MAX_NUMNODES]; | |
| 122 | 123 | |
| 123 | 124 | #ifndef set_numa_mem |
| 124 | 125 | static inline void set_numa_mem(int node) |
| 125 | 126 | { |
| 126 | 127 | this_cpu_write(_numa_mem_, node); |
| 128 | + _node_numa_mem_[numa_node_id()] = node; | |
| 127 | 129 | } |
| 128 | 130 | #endif |
| 129 | 131 | |
| 132 | +#ifndef node_to_mem_node | |
| 133 | +static inline int node_to_mem_node(int node) | |
| 134 | +{ | |
| 135 | + return _node_numa_mem_[node]; | |
| 136 | +} | |
| 137 | +#endif | |
| 138 | + | |
| 130 | 139 | #ifndef numa_mem_id |
| 131 | 140 | /* Returns the number of the nearest Node with memory */ |
| 132 | 141 | static inline int numa_mem_id(void) |
| ... | ... | @@ -146,6 +155,7 @@ |
| 146 | 155 | static inline void set_cpu_numa_mem(int cpu, int node) |
| 147 | 156 | { |
| 148 | 157 | per_cpu(_numa_mem_, cpu) = node; |
| 158 | + _node_numa_mem_[cpu_to_node(cpu)] = node; | |
| 149 | 159 | } |
| 150 | 160 | #endif |
| 151 | 161 | |
| ... | ... | @@ -156,6 +166,13 @@ |
| 156 | 166 | static inline int numa_mem_id(void) |
| 157 | 167 | { |
| 158 | 168 | return numa_node_id(); |
| 169 | +} | |
| 170 | +#endif | |
| 171 | + | |
| 172 | +#ifndef node_to_mem_node | |
| 173 | +static inline int node_to_mem_node(int node) | |
| 174 | +{ | |
| 175 | + return node; | |
| 159 | 176 | } |
| 160 | 177 | #endif |
| 161 | 178 |