linux-kernel - [tip:sched/urgent] sched/x86: Construct all sibling maps if smt

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Date:	Fri, 31 May 2013 05:50:12 -0700
From:	tip-bot for Andrew Jones <tipbot@...or.com>
To:	linux-tip-commits@...r.kernel.org
Cc:	linux-kernel@...r.kernel.org, hpa@...or.com, mingo@...nel.org,
	drjones@...hat.com, peterz@...radead.org, tglx@...utronix.de
Subject: [tip:sched/urgent] sched/x86: Construct all sibling maps if smt

Commit-ID:  b0bc225d0e5de887340d4d92a8c594ef0f60d412
Gitweb:     http://git.kernel.org/tip/b0bc225d0e5de887340d4d92a8c594ef0f60d412
Author:     Andrew Jones <drjones@...hat.com>
AuthorDate: Wed, 29 May 2013 14:48:15 +0200
Committer:  Ingo Molnar <mingo@...nel.org>
CommitDate: Fri, 31 May 2013 13:10:38 +0200

sched/x86: Construct all sibling maps if smt

Commit 316ad248307fb ("sched/x86: Rewrite
set_cpu_sibling_map()") broke the construction of sibling maps,
which also broke the booted_cores accounting.

Before the rewrite, if smt was present, then each map was
updated for each smt sibling. After the rewrite only
cpu_sibling_mask gets updated, as the llc and core maps depend
on 'has_mc = x86_max_cores > 1' instead. This leads to problems
with topologies like the following

(qemu -smp sockets=2,cores=1,threads=2)

  processor       : 0
  physical id     : 0
  siblings        : 1    <= should be 2
  core id         : 0
  cpu cores       : 1

  processor       : 1
  physical id     : 0
  siblings        : 1    <= should be 2
  core id         : 0
  cpu cores       : 0    <= should be 1

  processor       : 2
  physical id     : 1
  siblings        : 1    <= should be 2
  core id         : 0
  cpu cores       : 1

  processor       : 3
  physical id     : 1
  siblings        : 1    <= should be 2
  core id         : 0
  cpu cores       : 0    <= should be 1

This patch restores the former construction by defining has_mc
as (has_smt || x86_max_cores > 1). This should be fine as there
were no (has_smt && !has_mc) conditions in the context.

Aso rename has_mc to has_mp now that it's not just for cores.

Signed-off-by: Andrew Jones <drjones@...hat.com>
Acked-by: Peter Zijlstra <peterz@...radead.org>
Cc: a.p.zijlstra@...llo.nl
Cc: fenghua.yu@...el.com
Link: http://lkml.kernel.org/r/1369831695-11970-1-git-send-email-drjones@redhat.com
Signed-off-by: Ingo Molnar <mingo@...nel.org>
---
 arch/x86/kernel/smpboot.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
index 9c73b51..bfd348e 100644
--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -372,15 +372,15 @@ static bool __cpuinit match_mc(struct cpuinfo_x86 *c, struct cpuinfo_x86 *o)
 
 void __cpuinit set_cpu_sibling_map(int cpu)
 {
-	bool has_mc = boot_cpu_data.x86_max_cores > 1;
 	bool has_smt = smp_num_siblings > 1;
+	bool has_mp = has_smt || boot_cpu_data.x86_max_cores > 1;
 	struct cpuinfo_x86 *c = &cpu_data(cpu);
 	struct cpuinfo_x86 *o;
 	int i;
 
 	cpumask_set_cpu(cpu, cpu_sibling_setup_mask);
 
-	if (!has_smt && !has_mc) {
+	if (!has_mp) {
 		cpumask_set_cpu(cpu, cpu_sibling_mask(cpu));
 		cpumask_set_cpu(cpu, cpu_llc_shared_mask(cpu));
 		cpumask_set_cpu(cpu, cpu_core_mask(cpu));
@@ -394,7 +394,7 @@ void __cpuinit set_cpu_sibling_map(int cpu)
 		if ((i == cpu) || (has_smt && match_smt(c, o)))
 			link_mask(sibling, cpu, i);
 
-		if ((i == cpu) || (has_mc && match_llc(c, o)))
+		if ((i == cpu) || (has_mp && match_llc(c, o)))
 			link_mask(llc_shared, cpu, i);
 
 	}
@@ -406,7 +406,7 @@ void __cpuinit set_cpu_sibling_map(int cpu)
 	for_each_cpu(i, cpu_sibling_setup_mask) {
 		o = &cpu_data(i);
 
-		if ((i == cpu) || (has_mc && match_mc(c, o))) {
+		if ((i == cpu) || (has_mp && match_mc(c, o))) {
 			link_mask(core, cpu, i);
 
 			/*
--
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