Re: [Linaro-open-discussions] [PATCH 1/4] sched: Add infrastructure to describe if cluster scheduler is really running
-----Original Message----- From: Tim Chen [mailto:tim.c.chen@linux.intel.com] Sent: Friday, June 25, 2021 11:03 AM To: Song Bao Hua (Barry Song) song.bao.hua@hisilicon.com; yangyicong yangyicong@huawei.com Cc: guodong.xu@linaro.org; tangchengchang tangchengchang@huawei.com; Zengtao (B) prime.zeng@hisilicon.com; Jonathan Cameron jonathan.cameron@huawei.com; chenxiang (M) chenxiang66@hisilicon.com; Linuxarm linuxarm@huawei.com Subject: Re: [PATCH 1/4] sched: Add infrastructure to describe if cluster scheduler is really running
On 6/24/21 2:15 AM, Barry Song wrote:
use sched_cluster_present static key to describe if cluster scheduler is really working. and add sched_cluster_active() API to reflect the status of cluster scheduler as well. Only if cluster is bigger than smt, and less than coregroup, we are quite sure cluster scheduler is used.
Signed-off-by: Barry Song song.bao.hua@hisilicon.com
include/linux/sched/cluster.h | 19 +++++++++++++++++++ kernel/sched/core.c | 20 ++++++++++++++++++++ kernel/sched/fair.c | 4 ++++ kernel/sched/sched.h | 1 + 4 files changed, 44 insertions(+) create mode 100644 include/linux/sched/cluster.h
diff --git a/include/linux/sched/cluster.h b/include/linux/sched/cluster.h new file mode 100644 index 0000000..ea6c475 --- /dev/null +++ b/include/linux/sched/cluster.h @@ -0,0 +1,19 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef _LINUX_SCHED_CLUSTER_H +#define _LINUX_SCHED_CLUSTER_H
+#include <linux/static_key.h>
+#ifdef CONFIG_SCHED_CLUSTER +extern struct static_key_false sched_cluster_present;
+static __always_inline bool sched_cluster_active(void) +{
- return static_branch_likely(&sched_cluster_present);
Barry, we may encounter load where having the cluster sched domain is not productive. Wonder if we should add a run time sysfs control to turn on/off the sched cluster feature (for packing) and cluster sched domain (for spreading).
This is a bit orthogonal to this patch series but could be a 3rd patchset.
We may try though I am not sure if Peter is a fan of this kind of sysctl. This kind of thing is usually done by sched_feat():
There is a sysfs_feature ctl in /sys/kernel/debug/sched/features: kernel/sched/debug.c static int sched_feat_set(char *cmp) { int i; int neg = 0;
if (strncmp(cmp, "NO_", 3) == 0) { neg = 1; cmp += 3; }
i = match_string(sched_feat_names, __SCHED_FEAT_NR, cmp); if (i < 0) return i;
if (neg) { sysctl_sched_features &= ~(1UL << i); sched_feat_disable(i); } else { sysctl_sched_features |= (1UL << i); sched_feat_enable(i); }
return 0; }
Tim
+} +#else +static inline bool sched_cluster_active(void) { return false; }
+#endif
+#endif diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 9e9a5be..dd5984d 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -8655,6 +8655,17 @@ int sched_cpu_activate(unsigned int cpu) if (cpumask_weight(cpu_smt_mask(cpu)) == 2) static_branch_inc_cpuslocked(&sched_smt_present); #endif
+#ifdef CONFIG_SCHED_CLUSTER
- /*
* When going up, increment the number of cluster cpus with* cluster present.*/- if (cpumask_weight(cpu_cluster_mask(cpu)) >
cpumask_weight(cpu_smt_mask(cpu)) &&
cpumask_weight(cpu_cluster_mask(cpu)) <cpumask_weight(cpu_coregroup_mask(cpu)))
static_branch_inc_cpuslocked(&sched_cluster_present);+#endif
set_cpu_active(cpu, true);
if (sched_smp_initialized) {
@@ -8731,6 +8742,15 @@ int sched_cpu_deactivate(unsigned int cpu) static_branch_dec_cpuslocked(&sched_smt_present); #endif
+#ifdef CONFIG_SCHED_CLUSTER
- /*
* When going down, decrement the number of cpus with cluster present.*/- if (cpumask_weight(cpu_cluster_mask(cpu)) >
cpumask_weight(cpu_smt_mask(cpu)) &&
cpumask_weight(cpu_cluster_mask(cpu)) <cpumask_weight(cpu_coregroup_mask(cpu)))
static_branch_dec_cpuslocked(&sched_cluster_present);+#endif
- if (!sched_smp_initialized) return 0;
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index ce625bf..8578cb1 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -5997,6 +5997,10 @@ static inline int __select_idle_cpu(int cpu, struct
task_struct *p)
return -1; }
+#ifdef CONFIG_SCHED_CLUSTER +DEFINE_STATIC_KEY_FALSE(sched_cluster_present); +#endif
#ifdef CONFIG_SCHED_SMT DEFINE_STATIC_KEY_FALSE(sched_smt_present); EXPORT_SYMBOL_GPL(sched_smt_present); diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h index 8f0194c..0f8f610 100644 --- a/kernel/sched/sched.h +++ b/kernel/sched/sched.h @@ -6,6 +6,7 @@
#include <linux/sched/autogroup.h> #include <linux/sched/clock.h> +#include <linux/sched/cluster.h> #include <linux/sched/coredump.h> #include <linux/sched/cpufreq.h> #include <linux/sched/cputime.h>
Thanks Barry
linaro-open-discussions@op-lists.linaro.org
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Song Bao Hua (Barry Song)