Re: [PATCH v3] topology: add support for node_to_mem_node() to determine the fallback node
From: Andrew Morton <akpm@linux-foundation.org>
Date: 2014-09-10 00:11:18
Also in:
linux-mm
On Tue, 9 Sep 2014 12:03:27 -0700 Nishanth Aravamudan [off-list ref] wrote:
quoted hunk ↗ jump to hunk
From: Joonsoo Kim <redacted> 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. ...--- a/include/linux/topology.h +++ b/include/linux/topology.h@@ -119,11 +119,20 @@ static inline int numa_node_id(void) * Use the accessor functions set_numa_mem(), numa_mem_id() and cpu_to_mem().
This comment could be updated.
*/
DECLARE_PER_CPU(int, _numa_mem_);
+extern int _node_numa_mem_[MAX_NUMNODES];
#ifndef set_numa_mem
static inline void set_numa_mem(int node)
{
this_cpu_write(_numa_mem_, node);
+ _node_numa_mem_[numa_node_id()] = node;
+}
+#endif
+
+#ifndef node_to_mem_node
+static inline int node_to_mem_node(int node)
+{
+ return _node_numa_mem_[node];
}A wee bit of documentation wouldn't hurt. How does node_to_mem_node(numa_node_id()) differ from numa_mem_id()? If I'm reading things correctly, they should both always return the same thing. If so, do we need both? Will node_to_mem_node() ever actually be called with a node != numa_node_id()?
quoted hunk ↗ jump to hunk
#endif@@ -146,6 +155,7 @@ static inline int cpu_to_mem(int cpu) static inline void set_cpu_numa_mem(int cpu, int node) { per_cpu(_numa_mem_, cpu) = node; + _node_numa_mem_[cpu_to_node(cpu)] = node; } #endif@@ -159,6 +169,13 @@ static inline int numa_mem_id(void) } #endif +#ifndef node_to_mem_node +static inline int node_to_mem_node(int node) +{ + return node; +} +#endif + #ifndef cpu_to_mem static inline int cpu_to_mem(int cpu) {diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 18cee0d4c8a2..0883c42936d4 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c@@ -85,6 +85,7 @@ EXPORT_PER_CPU_SYMBOL(numa_node); */ DEFINE_PER_CPU(int, _numa_mem_); /* Kernel "local memory" node */ EXPORT_PER_CPU_SYMBOL(_numa_mem_); +int _node_numa_mem_[MAX_NUMNODES];
How does this get updated as CPUs, memory and nodes are hot-added and removed?
#endif