diff mbox

[RFC,v3,1/4] topology: add support for node_to_mem_node() to determine the fallback node

Message ID 20140814001422.GJ11121@linux.vnet.ibm.com (mailing list archive)
State RFC, archived
Headers show

Commit Message

Nishanth Aravamudan Aug. 14, 2014, 12:14 a.m. UTC 
From: Joonsoo Kim <iamjoonsoo.kim@lge.com>

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: Anton Blanchard <anton@samba.org>
Cc: Matt Mackall <mpm@selenic.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Wanpeng Li <liwanp@linux.vnet.ibm.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Linux Memory Management List <linux-mm@kvack.org>
Cc: linuxppc-dev@lists.ozlabs.org

---
v2 -> v3 (Nishanth):
  Fix declaration and definition of _node_numa_mem_.
  s/node_numa_mem/node_to_mem_node/ as suggested by David Rientjes.

Comments

Christoph Lameter (Ampere) Aug. 14, 2014, 2:35 p.m. UTC | #1 
On Wed, 13 Aug 2014, Nishanth Aravamudan wrote:

> +++ 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().
>   */
>  DECLARE_PER_CPU(int, _numa_mem_);
> +extern int _node_numa_mem_[MAX_NUMNODES];

Why are these variables starting with an _ ?
Maybe _numa_mem was defined that way because it is typically not defined.
We dont do this in other situations.
Nishanth Aravamudan Aug. 14, 2014, 8:06 p.m. UTC | #2 
On 14.08.2014 [09:35:37 -0500], Christoph Lameter wrote:
> On Wed, 13 Aug 2014, Nishanth Aravamudan wrote:
> 
> > +++ 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().
> >   */
> >  DECLARE_PER_CPU(int, _numa_mem_);
> > +extern int _node_numa_mem_[MAX_NUMNODES];
> 
> Why are these variables starting with an _ ?
> Maybe _numa_mem was defined that way because it is typically not defined.
> We dont do this in other situations.

That's how it was in Joonsoo's patch and I was trying to minimize the
changes from his version (beyond making it compile). I can of course
update it to not have a prefixing _ if that's preferred.

Thanks,
Nish
Nishanth Aravamudan Aug. 22, 2014, 9:52 p.m. UTC | #3 
Hi Christoph,

On 14.08.2014 [13:06:56 -0700], Nishanth Aravamudan wrote:
> On 14.08.2014 [09:35:37 -0500], Christoph Lameter wrote:
> > On Wed, 13 Aug 2014, Nishanth Aravamudan wrote:
> > 
> > > +++ 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().
> > >   */
> > >  DECLARE_PER_CPU(int, _numa_mem_);
> > > +extern int _node_numa_mem_[MAX_NUMNODES];
> > 
> > Why are these variables starting with an _ ?
> > Maybe _numa_mem was defined that way because it is typically not defined.
> > We dont do this in other situations.
> 
> That's how it was in Joonsoo's patch and I was trying to minimize the
> changes from his version (beyond making it compile). I can of course
> update it to not have a prefixing _ if that's preferred.

Upon reflection, did you mean all of these variables? Would you rather I
submitted a follow-on patch that removed the prefix _? Note that
_node_numa_mem_ is also not defined if !MEMORYLESS_NODES.

-Nish
diff mbox

Patch

diff --git a/include/linux/topology.h b/include/linux/topology.h
index dda6ee521e74..909b6e43b694 100644
--- 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().
  */
 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];
 }
 #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];
 #endif
 
 /*