linux-kernel - [tip:sched/core] sched/topology: Set correct NUMA topology type

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Message-ID: <tip-e5e96fafd9028b1478b165db78c52d981c14f471@git.kernel.org>
Date:   Mon, 10 Sep 2018 03:06:09 -0700
From:   tip-bot for Srikar Dronamraju <tipbot@...or.com>
To:     linux-tip-commits@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
        torvalds@...ux-foundation.org, wild@...ux.vnet.ibm.com,
        suravee.suthikulpanit@....com, hpa@...or.com, mingo@...nel.org,
        mpe@...erman.id.au, heiko.carstens@...ibm.com, tglx@...utronix.de,
        peterz@...radead.org, riel@...riel.com, srikar@...ux.vnet.ibm.com,
        mgorman@...hsingularity.net
Subject: [tip:sched/core] sched/topology: Set correct NUMA topology type

Commit-ID:  e5e96fafd9028b1478b165db78c52d981c14f471
Gitweb:     https://git.kernel.org/tip/e5e96fafd9028b1478b165db78c52d981c14f471
Author:     Srikar Dronamraju <srikar@...ux.vnet.ibm.com>
AuthorDate: Fri, 10 Aug 2018 22:30:18 +0530
Committer:  Ingo Molnar <mingo@...nel.org>
CommitDate: Mon, 10 Sep 2018 10:13:45 +0200

sched/topology: Set correct NUMA topology type

With the following commit:

  051f3ca02e46 ("sched/topology: Introduce NUMA identity node sched domain")

the scheduler introduced a new NUMA level. However this leads to the NUMA topology
on 2 node systems to not be marked as NUMA_DIRECT anymore.

After this commit, it gets reported as NUMA_BACKPLANE, because
sched_domains_numa_level is now 2 on 2 node systems.

Fix this by allowing setting systems that have up to 2 NUMA levels as
NUMA_DIRECT.

While here remove code that assumes that level can be 0.

Signed-off-by: Srikar Dronamraju <srikar@...ux.vnet.ibm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Cc: Andre Wild <wild@...ux.vnet.ibm.com>
Cc: Heiko Carstens <heiko.carstens@...ibm.com>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Mel Gorman <mgorman@...hsingularity.net>
Cc: Michael Ellerman <mpe@...erman.id.au>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Rik van Riel <riel@...riel.com>
Cc: Suravee Suthikulpanit <suravee.suthikulpanit@....com>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: linuxppc-dev <linuxppc-dev@...ts.ozlabs.org>
Fixes: 051f3ca02e46 "Introduce NUMA identity node sched domain"
Link: http://lkml.kernel.org/r/1533920419-17410-1-git-send-email-srikar@linux.vnet.ibm.com
Signed-off-by: Ingo Molnar <mingo@...nel.org>
---
 kernel/sched/topology.c | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/kernel/sched/topology.c b/kernel/sched/topology.c
index 56a0fed30c0a..505a41c42b96 100644
--- a/kernel/sched/topology.c
+++ b/kernel/sched/topology.c
@@ -1295,7 +1295,7 @@ static void init_numa_topology_type(void)
 
 	n = sched_max_numa_distance;
 
-	if (sched_domains_numa_levels <= 1) {
+	if (sched_domains_numa_levels <= 2) {
 		sched_numa_topology_type = NUMA_DIRECT;
 		return;
 	}
@@ -1380,9 +1380,6 @@ void sched_init_numa(void)
 			break;
 	}
 
-	if (!level)
-		return;
-
 	/*
 	 * 'level' contains the number of unique distances
 	 *