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Message-ID:
<ME0P300MB0414CFB62A0CEDF82333A7518E4B2@ME0P300MB0414.AUSP300.PROD.OUTLOOK.COM>
Date: Tue, 29 Oct 2024 04:26:37 +0000
From: 解 咏梅 <xieym_ict@...mail.com>
To: Tianchen Ding <dtcccc@...ux.alibaba.com>, "linux-kernel@...r.kernel.org"
<linux-kernel@...r.kernel.org>
CC: Ingo Molnar <mingo@...hat.com>, Peter Zijlstra <peterz@...radead.org>,
Juri Lelli <juri.lelli@...hat.com>, Vincent Guittot
<vincent.guittot@...aro.org>, Dietmar Eggemann <dietmar.eggemann@....com>,
Steven Rostedt <rostedt@...dmis.org>, Ben Segall <bsegall@...gle.com>, Mel
Gorman <mgorman@...e.de>, Valentin Schneider <vschneid@...hat.com>, Tejun Heo
<tj@...nel.org>
Subject:
回复: [RFC PATCH 2/2] sched/eevdf: Introduce a cgroup interface for slice
change to plain text to send to linux-kernel@...r.kernel.org
Sorry:(
________________________________________
发件人: 解 咏梅 <xieym_ict@...mail.com>
发送时间: 2024年10月29日 12:10
收件人: Tianchen Ding <dtcccc@...ux.alibaba.com>; linux-kernel@...r.kernel.org <linux-kernel@...r.kernel.org>
抄送: Ingo Molnar <mingo@...hat.com>; Peter Zijlstra <peterz@...radead.org>; Juri Lelli <juri.lelli@...hat.com>; Vincent Guittot <vincent.guittot@...aro.org>; Dietmar Eggemann <dietmar.eggemann@....com>; Steven Rostedt <rostedt@...dmis.org>; Ben Segall <bsegall@...gle.com>; Mel Gorman <mgorman@...e.de>; Valentin Schneider <vschneid@...hat.com>; Tejun Heo <tj@...nel.org>
主题: 回复: [RFC PATCH 2/2] sched/eevdf: Introduce a cgroup interface for slice
Interesting!
So, se's position in RB tree (aka se->deadline) is determined by 2 factors:
itself's total weighted runtime
tg's slice if defined or the queued cfs_rq's slice (the last one considers all ses beneth cfs_rq, so it's a dynamic slice)
As my understanding, this patch proposes a static slice for task cgroup. It might be useful in container colocation scenarios.
It's hard to detect the major product process in rich container scenario, because the user application is various and diverse.
Regards,
Yongmei.
________________________________________
发件人: Tianchen Ding <dtcccc@...ux.alibaba.com>
发送时间: 2024年10月28日 14:33
收件人: linux-kernel@...r.kernel.org <linux-kernel@...r.kernel.org>
抄送: Ingo Molnar <mingo@...hat.com>; Peter Zijlstra <peterz@...radead.org>; Juri Lelli <juri.lelli@...hat.com>; Vincent Guittot <vincent.guittot@...aro.org>; Dietmar Eggemann <dietmar.eggemann@....com>; Steven Rostedt <rostedt@...dmis.org>; Ben Segall <bsegall@...gle.com>; Mel Gorman <mgorman@...e.de>; Valentin Schneider <vschneid@...hat.com>; Tejun Heo <tj@...nel.org>
主题: [RFC PATCH 2/2] sched/eevdf: Introduce a cgroup interface for slice
Introduce "cpu.fair_slice" for cgroup v2 and "cpu.fair_slice_us" for v1
according to their name styles. The unit is always microseconds.
A cgroup with shorter slice can preempt others more easily. This could be
useful in container scenarios.
By default, cpu.fair_slice is 0, which means the slice of se is
calculated by min_slice from its cfs_rq. If cpu.fair_slice is set, it
will overwrite se->slice with the customized value.
Signed-off-by: Tianchen Ding <dtcccc@...ux.alibaba.com>
---
CC Tejun, do we need (and reuse) this slice interface for sched_ext?
---
kernel/sched/core.c | 34 ++++++++++++++++++++++++++++++
kernel/sched/fair.c | 49 +++++++++++++++++++++++++++++++++++++++-----
kernel/sched/sched.h | 3 +++
3 files changed, 81 insertions(+), 5 deletions(-)
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 114adac5a9c8..8d57b7d88d18 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -9690,6 +9690,24 @@ static int cpu_idle_write_s64(struct cgroup_subsys_state *css,
}
#endif
+#ifdef CONFIG_FAIR_GROUP_SCHED
+static u64 cpu_fair_slice_read_u64(struct cgroup_subsys_state *css,
+ struct cftype *cft)
+{
+ u64 fair_slice_us = css_tg(css)->slice;
+
+ do_div(fair_slice_us, NSEC_PER_USEC);
+
+ return fair_slice_us;
+}
+
+static int cpu_fair_slice_write_u64(struct cgroup_subsys_state *css,
+ struct cftype *cftype, u64 fair_slice_us)
+{
+ return sched_group_set_slice(css_tg(css), fair_slice_us);
+}
+#endif
+
static struct cftype cpu_legacy_files[] = {
#ifdef CONFIG_GROUP_SCHED_WEIGHT
{
@@ -9703,6 +9721,14 @@ static struct cftype cpu_legacy_files[] = {
.write_s64 = cpu_idle_write_s64,
},
#endif
+#ifdef CONFIG_FAIR_GROUP_SCHED
+ {
+ .name = "fair_slice_us",
+ .flags = CFTYPE_NOT_ON_ROOT,
+ .read_u64 = cpu_fair_slice_read_u64,
+ .write_u64 = cpu_fair_slice_write_u64,
+ },
+#endif
#ifdef CONFIG_CFS_BANDWIDTH
{
.name = "cfs_quota_us",
@@ -9943,6 +9969,14 @@ static struct cftype cpu_files[] = {
.write_s64 = cpu_idle_write_s64,
},
#endif
+#ifdef CONFIG_FAIR_GROUP_SCHED
+ {
+ .name = "fair_slice",
+ .flags = CFTYPE_NOT_ON_ROOT,
+ .read_u64 = cpu_fair_slice_read_u64,
+ .write_u64 = cpu_fair_slice_write_u64,
+ },
+#endif
#ifdef CONFIG_CFS_BANDWIDTH
{
.name = "max",
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 7dc90a6e6e26..694dc0655719 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -797,6 +797,11 @@ static inline u64 cfs_rq_min_slice(struct cfs_rq *cfs_rq)
return min_slice;
}
+static inline u64 cfs_rq_slice(struct cfs_rq *cfs_rq)
+{
+ return cfs_rq->tg->slice ? : cfs_rq_min_slice(cfs_rq);
+}
+
static inline bool __entity_less(struct rb_node *a, const struct rb_node *b)
{
return entity_before(__node_2_se(a), __node_2_se(b));
@@ -6994,7 +6999,7 @@ enqueue_task_fair(struct rq *rq, struct task_struct *p, int flags)
se->custom_slice = 1;
}
enqueue_entity(cfs_rq, se, flags);
- slice = cfs_rq_min_slice(cfs_rq);
+ slice = cfs_rq_slice(cfs_rq);
cfs_rq->h_nr_running++;
cfs_rq->idle_h_nr_running += idle_h_nr_running;
@@ -7018,7 +7023,7 @@ enqueue_task_fair(struct rq *rq, struct task_struct *p, int flags)
se->slice = slice;
min_vruntime_cb_propagate(&se->run_node, NULL);
- slice = cfs_rq_min_slice(cfs_rq);
+ slice = cfs_rq_slice(cfs_rq);
cfs_rq->h_nr_running++;
cfs_rq->idle_h_nr_running += idle_h_nr_running;
@@ -7093,7 +7098,7 @@ static int dequeue_entities(struct rq *rq, struct sched_entity *se, int flags)
idle_h_nr_running = task_has_idle_policy(p);
} else {
cfs_rq = group_cfs_rq(se);
- slice = cfs_rq_min_slice(cfs_rq);
+ slice = cfs_rq_slice(cfs_rq);
}
for_each_sched_entity(se) {
@@ -7118,7 +7123,7 @@ static int dequeue_entities(struct rq *rq, struct sched_entity *se, int flags)
/* Don't dequeue parent if it has other entities besides us */
if (cfs_rq->load.weight) {
- slice = cfs_rq_min_slice(cfs_rq);
+ slice = cfs_rq_slice(cfs_rq);
/* Avoid re-evaluating load for this entity: */
se = parent_entity(se);
@@ -7143,7 +7148,7 @@ static int dequeue_entities(struct rq *rq, struct sched_entity *se, int flags)
se->slice = slice;
min_vruntime_cb_propagate(&se->run_node, NULL);
- slice = cfs_rq_min_slice(cfs_rq);
+ slice = cfs_rq_slice(cfs_rq);
cfs_rq->h_nr_running -= h_nr_running;
cfs_rq->idle_h_nr_running -= idle_h_nr_running;
@@ -13535,6 +13540,40 @@ int sched_group_set_idle(struct task_group *tg, long idle)
return 0;
}
+int sched_group_set_slice(struct task_group *tg, u64 fair_slice_us)
+{
+ u64 slice = 0;
+ int i;
+
+ if (fair_slice_us > U64_MAX / NSEC_PER_USEC)
+ return -EINVAL;
+
+ if (fair_slice_us) {
+ slice = clamp_t(u64, fair_slice_us * NSEC_PER_USEC,
+ NSEC_PER_MSEC / 10, /* HZ = 1000 * 10 */
+ NSEC_PER_MSEC * 100); /* HZ = 100 / 10 */
+ }
+
+ if (slice == tg->slice)
+ return 0;
+
+ tg->slice = slice;
+
+ for_each_possible_cpu(i) {
+ struct sched_entity *se = tg->se[i];
+ struct rq *rq = cpu_rq(i);
+
+ guard(rq_lock_irqsave)(rq);
+ for_each_sched_entity(se) {
+ se->custom_slice = 1;
+ se->slice = cfs_rq_slice(group_cfs_rq(se));
+ min_vruntime_cb_propagate(&se->run_node, NULL);
+ }
+ }
+
+ return 0;
+}
+
#endif /* CONFIG_FAIR_GROUP_SCHED */
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index 7b139016cbd9..e02f8715bc04 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -443,6 +443,7 @@ struct task_group {
/* runqueue "owned" by this group on each CPU */
struct cfs_rq **cfs_rq;
unsigned long shares;
+ u64 slice;
#ifdef CONFIG_SMP
/*
* load_avg can be heavily contended at clock tick time, so put
@@ -574,6 +575,8 @@ extern int sched_group_set_shares(struct task_group *tg, unsigned long shares);
extern int sched_group_set_idle(struct task_group *tg, long idle);
+extern int sched_group_set_slice(struct task_group *tg, u64 fair_slice_us);
+
#ifdef CONFIG_SMP
extern void set_task_rq_fair(struct sched_entity *se,
struct cfs_rq *prev, struct cfs_rq *next);
--
2.39.3
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