There were several commits interspersed with sched/topology fixes upstream that I thought were cleanup and therefore didn't backport to the 3.16 stable branch. Now I suspect that at least some of them are needed. I'm attaching backports of 3 of the commits that I left out. Can you test whether they fix the regression for you? If this doesn't help, I think we may just have to revert the sched/topology fixes. Ben. -- Ben Hutchings A free society is one where it is safe to be unpopular. - Adlai Stevenson
From: Peter Zijlstra <peterz@infradead.org>
Date: Fri, 14 Apr 2017 17:32:07 +0200
Subject: sched/topology: Simplify build_overlap_sched_groups()
Origin: https://git.kernel.org/linus/91eaed0d61319f58a9f8e43d41a8cbb069b4f73d
Now that the first group will always be the previous domain of this
@cpu this can be simplified.
In fact, writing the code now removed should've been a big clue I was
doing it wrong :/
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
[bwh: Backported to 3.16: adjust filename, context]
---
kernel/sched/topology.c | 13 ++-----------
1 file changed, 2 insertions(+), 11 deletions(-)
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 921dedde2ee1..6b10e0a956c7 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -557,7 +557,7 @@ static void init_overlap_sched_group(struct sched_domain *sd,
static int
build_overlap_sched_groups(struct sched_domain *sd, int cpu)
{
- struct sched_group *first = NULL, *last = NULL, *groups = NULL, *sg;
+ struct sched_group *first = NULL, *last = NULL, *sg;
const struct cpumask *span = sched_domain_span(sd);
struct cpumask *covered = sched_domains_tmpmask;
struct sd_data *sdd = sd->private;
@@ -587,15 +587,6 @@ build_overlap_sched_groups(struct sched_domain *sd, int cpu)
init_overlap_sched_group(sd, sg);
- /*
- * Make sure the first group of this domain contains the
- * canonical balance cpu. Otherwise the sched_domain iteration
- * breaks. See update_sg_lb_stats().
- */
- if ((!groups && cpumask_test_cpu(cpu, sg_span)) ||
- group_balance_cpu(sg) == cpu)
- groups = sg;
-
if (!first)
first = sg;
if (last)
@@ -603,7 +594,7 @@ build_overlap_sched_groups(struct sched_domain *sd, int cpu)
last = sg;
last->next = first;
}
- sd->groups = groups;
+ sd->groups = first;
return 0;
From 5727151be2afd55868244c2621ce0e350eecdc8d Mon Sep 17 00:00:00 2001
From: Peter Zijlstra <peterz@infradead.org>
Date: Fri, 14 Apr 2017 17:32:07 +0200
Subject: [PATCH 2/3] sched/topology: Simplify build_overlap_sched_groups()
commit 91eaed0d61319f58a9f8e43d41a8cbb069b4f73d upstream.
Now that the first group will always be the previous domain of this
@cpu this can be simplified.
In fact, writing the code now removed should've been a big clue I was
doing it wrong :/
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
[bwh: Backported to 3.16: adjust filename, context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
kernel/sched/core.c | 13 ++-----------
1 file changed, 2 insertions(+), 11 deletions(-)
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 0692ee2dd889..68bc1bf9f5ab 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -5869,7 +5869,7 @@ static void init_overlap_sched_group(struct sched_domain *sd,
static int
build_overlap_sched_groups(struct sched_domain *sd, int cpu)
{
- struct sched_group *first = NULL, *last = NULL, *groups = NULL, *sg;
+ struct sched_group *first = NULL, *last = NULL, *sg;
const struct cpumask *span = sched_domain_span(sd);
struct cpumask *covered = sched_domains_tmpmask;
struct sd_data *sdd = sd->private;
@@ -5899,15 +5899,6 @@ build_overlap_sched_groups(struct sched_domain *sd, int cpu)
init_overlap_sched_group(sd, sg);
- /*
- * Make sure the first group of this domain contains the
- * canonical balance cpu. Otherwise the sched_domain iteration
- * breaks. See update_sg_lb_stats().
- */
- if ((!groups && cpumask_test_cpu(cpu, sg_span)) ||
- group_balance_cpu(sg) == cpu)
- groups = sg;
-
if (!first)
first = sg;
if (last)
@@ -5915,7 +5906,7 @@ build_overlap_sched_groups(struct sched_domain *sd, int cpu)
last = sg;
last->next = first;
}
- sd->groups = groups;
+ sd->groups = first;
return 0;
From 10f83418ab83f5d4ff5f7bc53cbd3f9455981186 Mon Sep 17 00:00:00 2001
From: Lauro Ramos Venancio <lvenanci@redhat.com>
Date: Thu, 20 Apr 2017 16:51:40 -0300
Subject: [PATCH 3/3] sched/topology: Optimize build_group_mask()
commit f32d782e31bf079f600dcec126ed117b0577e85c upstream.
The group mask is always used in intersection with the group CPUs. So,
when building the group mask, we don't have to care about CPUs that are
not part of the group.
Signed-off-by: Lauro Ramos Venancio <lvenanci@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: lwang@redhat.com
Cc: riel@redhat.com
Link: http://lkml.kernel.org/r/1492717903-5195-2-git-send-email-lvenanci@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
[bwh: Backported to 3.16:
- Update another reference to 'span' introduced by an earlier backport of
sched/topology changes
- Adjust filename]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
kernel/sched/core.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 68bc1bf9f5ab..e6c9458f4b49 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -5782,14 +5782,14 @@ enum s_alloc {
static void
build_group_mask(struct sched_domain *sd, struct sched_group *sg, struct cpumask *mask)
{
- const struct cpumask *span = sched_domain_span(sd);
+ const struct cpumask *sg_span = sched_group_cpus(sg);
struct sd_data *sdd = sd->private;
struct sched_domain *sibling;
int i;
cpumask_clear(mask);
- for_each_cpu(i, span) {
+ for_each_cpu(i, sg_span) {
sibling = *per_cpu_ptr(sdd->sd, i);
/*
@@ -5801,7 +5801,7 @@ build_group_mask(struct sched_domain *sd, struct sched_group *sg, struct cpumask
continue;
/* If we would not end up here, we can't continue from here */
- if (!cpumask_equal(span, sched_domain_span(sibling->child)))
+ if (!cpumask_equal(sg_span, sched_domain_span(sibling->child)))
continue;
cpumask_set_cpu(i, mask);
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