* [PATCH RESEND] sched/fair: Fix wrong cpu selecting from isolated domain
@ 2020-09-24 6:48 Xunlei Pang
2020-09-24 7:18 ` Vincent Guittot
2020-09-29 7:56 ` [tip: sched/core] " tip-bot2 for Xunlei Pang
0 siblings, 2 replies; 4+ messages in thread
From: Xunlei Pang @ 2020-09-24 6:48 UTC (permalink / raw)
To: Ingo Molnar, Peter Zijlstra, Juri Lelli, Vincent Guittot, Jiang Biao
Cc: Wetp Zhang, linux-kernel
We've met problems that occasionally tasks with full cpumask
(e.g. by putting it into a cpuset or setting to full affinity)
were migrated to our isolated cpus in production environment.
After some analysis, we found that it is due to the current
select_idle_smt() not considering the sched_domain mask.
Steps to reproduce on my 31-CPU hyperthreads machine:
1. with boot parameter: "isolcpus=domain,2-31"
(thread lists: 0,16 and 1,17)
2. cgcreate -g cpu:test; cgexec -g cpu:test "test_threads"
3. some threads will be migrated to the isolated cpu16~17.
Fix it by checking the valid domain mask in select_idle_smt().
Fixes: 10e2f1acd010 ("sched/core: Rewrite and improve select_idle_siblings())
Reported-by: Wetp Zhang <wetp.zy@linux.alibaba.com>
Reviewed-by: Jiang Biao <benbjiang@tencent.com>
Signed-off-by: Xunlei Pang <xlpang@linux.alibaba.com>
---
kernel/sched/fair.c | 9 +++++----
1 file changed, 5 insertions(+), 4 deletions(-)
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 1a68a05..fa942c4 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -6075,7 +6075,7 @@ static int select_idle_core(struct task_struct *p, struct sched_domain *sd, int
/*
* Scan the local SMT mask for idle CPUs.
*/
-static int select_idle_smt(struct task_struct *p, int target)
+static int select_idle_smt(struct task_struct *p, struct sched_domain *sd, int target)
{
int cpu;
@@ -6083,7 +6083,8 @@ static int select_idle_smt(struct task_struct *p, int target)
return -1;
for_each_cpu(cpu, cpu_smt_mask(target)) {
- if (!cpumask_test_cpu(cpu, p->cpus_ptr))
+ if (!cpumask_test_cpu(cpu, p->cpus_ptr) ||
+ !cpumask_test_cpu(cpu, sched_domain_span(sd)))
continue;
if (available_idle_cpu(cpu) || sched_idle_cpu(cpu))
return cpu;
@@ -6099,7 +6100,7 @@ static inline int select_idle_core(struct task_struct *p, struct sched_domain *s
return -1;
}
-static inline int select_idle_smt(struct task_struct *p, int target)
+static inline int select_idle_smt(struct task_struct *p, struct sched_domain *sd, int target)
{
return -1;
}
@@ -6274,7 +6275,7 @@ static int select_idle_sibling(struct task_struct *p, int prev, int target)
if ((unsigned)i < nr_cpumask_bits)
return i;
- i = select_idle_smt(p, target);
+ i = select_idle_smt(p, sd, target);
if ((unsigned)i < nr_cpumask_bits)
return i;
--
1.8.3.1
^ permalink raw reply related [flat|nested] 4+ messages in thread* Re: [PATCH RESEND] sched/fair: Fix wrong cpu selecting from isolated domain
2020-09-24 6:48 [PATCH RESEND] sched/fair: Fix wrong cpu selecting from isolated domain Xunlei Pang
@ 2020-09-24 7:18 ` Vincent Guittot
2020-09-24 8:54 ` Xunlei Pang
2020-09-29 7:56 ` [tip: sched/core] " tip-bot2 for Xunlei Pang
1 sibling, 1 reply; 4+ messages in thread
From: Vincent Guittot @ 2020-09-24 7:18 UTC (permalink / raw)
To: Xunlei Pang
Cc: Ingo Molnar, Peter Zijlstra, Juri Lelli, Jiang Biao, Wetp Zhang,
linux-kernel
On Thu, 24 Sep 2020 at 08:48, Xunlei Pang <xlpang@linux.alibaba.com> wrote:
>
> We've met problems that occasionally tasks with full cpumask
> (e.g. by putting it into a cpuset or setting to full affinity)
> were migrated to our isolated cpus in production environment.
>
> After some analysis, we found that it is due to the current
> select_idle_smt() not considering the sched_domain mask.
>
> Steps to reproduce on my 31-CPU hyperthreads machine:
> 1. with boot parameter: "isolcpus=domain,2-31"
> (thread lists: 0,16 and 1,17)
> 2. cgcreate -g cpu:test; cgexec -g cpu:test "test_threads"
> 3. some threads will be migrated to the isolated cpu16~17.
>
> Fix it by checking the valid domain mask in select_idle_smt().
>
> Fixes: 10e2f1acd010 ("sched/core: Rewrite and improve select_idle_siblings())
> Reported-by: Wetp Zhang <wetp.zy@linux.alibaba.com>
> Reviewed-by: Jiang Biao <benbjiang@tencent.com>
> Signed-off-by: Xunlei Pang <xlpang@linux.alibaba.com>
Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>
> ---
> kernel/sched/fair.c | 9 +++++----
> 1 file changed, 5 insertions(+), 4 deletions(-)
>
> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
> index 1a68a05..fa942c4 100644
> --- a/kernel/sched/fair.c
> +++ b/kernel/sched/fair.c
> @@ -6075,7 +6075,7 @@ static int select_idle_core(struct task_struct *p, struct sched_domain *sd, int
> /*
> * Scan the local SMT mask for idle CPUs.
> */
> -static int select_idle_smt(struct task_struct *p, int target)
> +static int select_idle_smt(struct task_struct *p, struct sched_domain *sd, int target)
> {
> int cpu;
>
> @@ -6083,7 +6083,8 @@ static int select_idle_smt(struct task_struct *p, int target)
> return -1;
>
> for_each_cpu(cpu, cpu_smt_mask(target)) {
> - if (!cpumask_test_cpu(cpu, p->cpus_ptr))
> + if (!cpumask_test_cpu(cpu, p->cpus_ptr) ||
> + !cpumask_test_cpu(cpu, sched_domain_span(sd)))
> continue;
> if (available_idle_cpu(cpu) || sched_idle_cpu(cpu))
> return cpu;
> @@ -6099,7 +6100,7 @@ static inline int select_idle_core(struct task_struct *p, struct sched_domain *s
> return -1;
> }
>
> -static inline int select_idle_smt(struct task_struct *p, int target)
> +static inline int select_idle_smt(struct task_struct *p, struct sched_domain *sd, int target)
> {
> return -1;
> }
> @@ -6274,7 +6275,7 @@ static int select_idle_sibling(struct task_struct *p, int prev, int target)
> if ((unsigned)i < nr_cpumask_bits)
> return i;
>
> - i = select_idle_smt(p, target);
> + i = select_idle_smt(p, sd, target);
> if ((unsigned)i < nr_cpumask_bits)
> return i;
>
> --
> 1.8.3.1
>
^ permalink raw reply [flat|nested] 4+ messages in thread* Re: [PATCH RESEND] sched/fair: Fix wrong cpu selecting from isolated domain
2020-09-24 7:18 ` Vincent Guittot
@ 2020-09-24 8:54 ` Xunlei Pang
0 siblings, 0 replies; 4+ messages in thread
From: Xunlei Pang @ 2020-09-24 8:54 UTC (permalink / raw)
To: Vincent Guittot, Xunlei Pang
Cc: Ingo Molnar, Peter Zijlstra, Juri Lelli, Jiang Biao, Wetp Zhang,
linux-kernel
On 9/24/20 3:18 PM, Vincent Guittot wrote:
> On Thu, 24 Sep 2020 at 08:48, Xunlei Pang <xlpang@linux.alibaba.com> wrote:
>>
>> We've met problems that occasionally tasks with full cpumask
>> (e.g. by putting it into a cpuset or setting to full affinity)
>> were migrated to our isolated cpus in production environment.
>>
>> After some analysis, we found that it is due to the current
>> select_idle_smt() not considering the sched_domain mask.
>>
>> Steps to reproduce on my 31-CPU hyperthreads machine:
>> 1. with boot parameter: "isolcpus=domain,2-31"
>> (thread lists: 0,16 and 1,17)
>> 2. cgcreate -g cpu:test; cgexec -g cpu:test "test_threads"
>> 3. some threads will be migrated to the isolated cpu16~17.
>>
>> Fix it by checking the valid domain mask in select_idle_smt().
>>
>> Fixes: 10e2f1acd010 ("sched/core: Rewrite and improve select_idle_siblings())
>> Reported-by: Wetp Zhang <wetp.zy@linux.alibaba.com>
>> Reviewed-by: Jiang Biao <benbjiang@tencent.com>
>> Signed-off-by: Xunlei Pang <xlpang@linux.alibaba.com>
>
> Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>
>
Thanks, Vincent :-)
^ permalink raw reply [flat|nested] 4+ messages in thread
* [tip: sched/core] sched/fair: Fix wrong cpu selecting from isolated domain
2020-09-24 6:48 [PATCH RESEND] sched/fair: Fix wrong cpu selecting from isolated domain Xunlei Pang
2020-09-24 7:18 ` Vincent Guittot
@ 2020-09-29 7:56 ` tip-bot2 for Xunlei Pang
1 sibling, 0 replies; 4+ messages in thread
From: tip-bot2 for Xunlei Pang @ 2020-09-29 7:56 UTC (permalink / raw)
To: linux-tip-commits
Cc: Wetp Zhang, Xunlei Pang, Peter Zijlstra (Intel),
Jiang Biao, Vincent Guittot, x86, LKML
The following commit has been merged into the sched/core branch of tip:
Commit-ID: df3cb4ea1fb63ff326488efd671ba3c39034255e
Gitweb: https://git.kernel.org/tip/df3cb4ea1fb63ff326488efd671ba3c39034255e
Author: Xunlei Pang <xlpang@linux.alibaba.com>
AuthorDate: Thu, 24 Sep 2020 14:48:47 +08:00
Committer: Peter Zijlstra <peterz@infradead.org>
CommitterDate: Fri, 25 Sep 2020 14:23:25 +02:00
sched/fair: Fix wrong cpu selecting from isolated domain
We've met problems that occasionally tasks with full cpumask
(e.g. by putting it into a cpuset or setting to full affinity)
were migrated to our isolated cpus in production environment.
After some analysis, we found that it is due to the current
select_idle_smt() not considering the sched_domain mask.
Steps to reproduce on my 31-CPU hyperthreads machine:
1. with boot parameter: "isolcpus=domain,2-31"
(thread lists: 0,16 and 1,17)
2. cgcreate -g cpu:test; cgexec -g cpu:test "test_threads"
3. some threads will be migrated to the isolated cpu16~17.
Fix it by checking the valid domain mask in select_idle_smt().
Fixes: 10e2f1acd010 ("sched/core: Rewrite and improve select_idle_siblings())
Reported-by: Wetp Zhang <wetp.zy@linux.alibaba.com>
Signed-off-by: Xunlei Pang <xlpang@linux.alibaba.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Jiang Biao <benbjiang@tencent.com>
Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>
Link: https://lkml.kernel.org/r/1600930127-76857-1-git-send-email-xlpang@linux.alibaba.com
---
kernel/sched/fair.c | 9 +++++----
1 file changed, 5 insertions(+), 4 deletions(-)
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index a15deb2..9613e5d 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -6080,7 +6080,7 @@ static int select_idle_core(struct task_struct *p, struct sched_domain *sd, int
/*
* Scan the local SMT mask for idle CPUs.
*/
-static int select_idle_smt(struct task_struct *p, int target)
+static int select_idle_smt(struct task_struct *p, struct sched_domain *sd, int target)
{
int cpu;
@@ -6088,7 +6088,8 @@ static int select_idle_smt(struct task_struct *p, int target)
return -1;
for_each_cpu(cpu, cpu_smt_mask(target)) {
- if (!cpumask_test_cpu(cpu, p->cpus_ptr))
+ if (!cpumask_test_cpu(cpu, p->cpus_ptr) ||
+ !cpumask_test_cpu(cpu, sched_domain_span(sd)))
continue;
if (available_idle_cpu(cpu) || sched_idle_cpu(cpu))
return cpu;
@@ -6104,7 +6105,7 @@ static inline int select_idle_core(struct task_struct *p, struct sched_domain *s
return -1;
}
-static inline int select_idle_smt(struct task_struct *p, int target)
+static inline int select_idle_smt(struct task_struct *p, struct sched_domain *sd, int target)
{
return -1;
}
@@ -6279,7 +6280,7 @@ symmetric:
if ((unsigned)i < nr_cpumask_bits)
return i;
- i = select_idle_smt(p, target);
+ i = select_idle_smt(p, sd, target);
if ((unsigned)i < nr_cpumask_bits)
return i;
^ permalink raw reply related [flat|nested] 4+ messages in thread
end of thread, other threads:[~2020-09-29 7:57 UTC | newest]
Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2020-09-24 6:48 [PATCH RESEND] sched/fair: Fix wrong cpu selecting from isolated domain Xunlei Pang
2020-09-24 7:18 ` Vincent Guittot
2020-09-24 8:54 ` Xunlei Pang
2020-09-29 7:56 ` [tip: sched/core] " tip-bot2 for Xunlei Pang
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).