linux-kernel - [PATCH RFC 5/5] powerpc:numa Use chipid to nid mapping to get serial numa node ids

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Date:	Sun, 27 Sep 2015 23:59:13 +0530
From:	Raghavendra K T <raghavendra.kt@...ux.vnet.ibm.com>
To:	<benh@...nel.crashing.org>, <paulus@...ba.org>,
	<mpe@...erman.id.au>
Cc:	<anton@...ba.org>, <linuxppc-dev@...ts.ozlabs.org>,
	<linux-kernel@...r.kernel.org>, <cl@...ux.com>,
	<nacc@...ux.vnet.ibm.com>, <gkurz@...ux.vnet.ibm.com>,
	<grant.likely@...aro.org>, <nikunj@...ux.vnet.ibm.com>,
	<raghavendra.kt@...ux.vnet.ibm.com>, <khandual@...ux.vnet.ibm.com>
Subject: [PATCH RFC  5/5] powerpc:numa Use chipid to nid mapping to get serial numa node ids

Also properly initialize numa distance table for serial nids.

Problem: Powerpc supports sparse nid numbering which could affect
1) memory footprint 2) virtualization use cases

Current solution:
The patch maps sprase chipid got fromn device tree to serail
nids.

Result before:
node   0   1  16  17
  0:  10  20  40  40
  1:  20  10  40  40
 16:  40  40  10  20
 17:  40  40  20  10

After:
node   0   1   2   3
  0:  10  20  40  40
  1:  20  10  40  40
  2:  40  40  10  20
  3:  40  40  20  10

Testing: Scenarios tested on  baremetal and KVM guest with 4 nodes
1) offlining and onlining memory and cpus
2) Running the tests from numactl source.
3) Creating 1000s of docker containers stressing the system

Signed-off-by: Raghavendra K T <raghavendra.kt@...ux.vnet.ibm.com>
---
 arch/powerpc/mm/numa.c | 13 ++++++++-----
 1 file changed, 8 insertions(+), 5 deletions(-)

diff --git a/arch/powerpc/mm/numa.c b/arch/powerpc/mm/numa.c
index f015cad..873ac8c 100644
--- a/arch/powerpc/mm/numa.c
+++ b/arch/powerpc/mm/numa.c
@@ -304,7 +304,8 @@ static int associativity_to_chipid(const __be32 *associativity)
 		/*
 		 * Skip the length field and send start of associativity array
 		 */
-		initialize_distance_lookup_table(chipid, associativity + 1);
+		initialize_distance_lookup_table(chipid_to_nid(chipid),
+						 associativity + 1);
 	}
 
 out:
@@ -314,9 +315,10 @@ out:
  /* Return the nid from associativity */
 static int associativity_to_nid(const __be32 *associativity)
 {
-	int nid;
+	int chipid, nid;
 
-	nid = associativity_to_chipid(associativity);
+	chipid = associativity_to_chipid(associativity);
+	nid = map_chipid_to_nid(chipid);
 	return nid;
 }
 
@@ -340,9 +342,10 @@ static int of_node_to_chipid_single(struct device_node *device)
  */
 static int of_node_to_nid_single(struct device_node *device)
 {
-	int nid;
+	int chipid, nid;
 
-	nid = of_node_to_chipid_single(device);
+	chipid = of_node_to_chipid_single(device);
+	nid = map_chipid_to_nid(chipid);
 	return nid;
 }
 
-- 
1.7.11.7

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