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Date: Wed, 21 Jul 2021 15:57:51 +0800
From: Xuewen Yan <xuewen.yan94@...il.com>
To: dietmar.eggemann@....com, mingo@...hat.com, peterz@...radead.org,
juri.lelli@...hat.com, vincent.guittot@...aro.org
Cc: rostedt@...dmis.org, bsegall@...gle.com, mgorman@...e.de,
bristot@...hat.com, mcgrof@...nel.org, keescook@...omium.org,
yzaikin@...gle.com, pjt@...gle.com, qais.yousef@....com,
qperret@...gle.com, linux-kernel@...r.kernel.org,
linux-fsdevel@...r.kernel.org
Subject: [PATCH] sched/uclamp: Introduce a method to transform UCLAMP_MIN into BOOST
From: Xuewen Yan <xuewen.yan@...soc.com>
The uclamp can clamp the util within uclamp_min and uclamp_max,
it is benifit to some tasks with small util, but for those tasks
with middle util, it is useless.
To speed up those tasks, convert UCLAMP_MIN to BOOST,
the BOOST as schedtune does:
boot = uclamp_min / SCHED_CAPACITY_SCALE;
margin = boost * (uclamp_max - util)
boost_util = util + margin;
Scenario:
if the task_util = 200, {uclamp_min, uclamp_max} = {100, 1024}
without patch:
clamp_util = 200;
with patch:
clamp_util = 200 + (100 / 1024) * (1024 - 200) = 280;
On the other hand, adding a SYS interface to allow users
to configure it according to their own needs.
Signed-off-by: Xuewen Yan <xuewen.yan@...soc.com>
---
include/linux/sched/sysctl.h | 1 +
kernel/sched/core.c | 19 +++++++++++++++++++
kernel/sched/fair.c | 15 ++++++++++++---
kernel/sched/sched.h | 10 +++++++++-
kernel/sysctl.c | 9 +++++++++
5 files changed, 50 insertions(+), 4 deletions(-)
diff --git a/include/linux/sched/sysctl.h b/include/linux/sched/sysctl.h
index db2c0f34aaaf..97d8c5ecd4e6 100644
--- a/include/linux/sched/sysctl.h
+++ b/include/linux/sched/sysctl.h
@@ -69,6 +69,7 @@ extern unsigned int sysctl_sched_dl_period_min;
extern unsigned int sysctl_sched_uclamp_util_min;
extern unsigned int sysctl_sched_uclamp_util_max;
extern unsigned int sysctl_sched_uclamp_util_min_rt_default;
+extern unsigned int sysctl_sched_uclamp_min_to_boost;
#endif
#ifdef CONFIG_CFS_BANDWIDTH
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 2d9ff40f4661..8a49f9962cda 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -1245,6 +1245,9 @@ unsigned int sysctl_sched_uclamp_util_max = SCHED_CAPACITY_SCALE;
*/
unsigned int sysctl_sched_uclamp_util_min_rt_default = SCHED_CAPACITY_SCALE;
+/* map util clamp_min to boost */
+unsigned int sysctl_sched_uclamp_min_to_boost;
+
/* All clamps are required to be less or equal than these values */
static struct uclamp_se uclamp_default[UCLAMP_CNT];
@@ -1448,6 +1451,22 @@ uclamp_eff_get(struct task_struct *p, enum uclamp_id clamp_id)
return uc_req;
}
+unsigned long uclamp_transform_boost(unsigned long util, unsigned long uclamp_min,
+ unsigned long uclamp_max)
+{
+ unsigned long margin;
+
+ if (unlikely(uclamp_min > uclamp_max))
+ return util;
+
+ if (util >= uclamp_max)
+ return uclamp_max;
+
+ margin = DIV_ROUND_CLOSEST_ULL(uclamp_min * (uclamp_max - util),
+ SCHED_CAPACITY_SCALE);
+ return util + margin;
+}
+
unsigned long uclamp_eff_value(struct task_struct *p, enum uclamp_id clamp_id)
{
struct uclamp_se uc_eff;
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 44c452072a1b..790dfbb6c897 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -3934,9 +3934,18 @@ static inline unsigned long task_util_est(struct task_struct *p)
#ifdef CONFIG_UCLAMP_TASK
static inline unsigned long uclamp_task_util(struct task_struct *p)
{
- return clamp(task_util_est(p),
- uclamp_eff_value(p, UCLAMP_MIN),
- uclamp_eff_value(p, UCLAMP_MAX));
+ unsigned long min_util = uclamp_eff_value(p, UCLAMP_MIN);
+ unsigned long max_util = uclamp_eff_value(p, UCLAMP_MAX);
+ unsigned long clamp_util, util;
+
+ util = task_util_est(p);
+
+ if (sysctl_sched_uclamp_min_to_boost)
+ clamp_util = uclamp_transform_boost(util, min_util, max_util);
+ else
+ clamp_util = clamp(util, min_util, max_util);
+
+ return clamp_util;
}
#else
static inline unsigned long uclamp_task_util(struct task_struct *p)
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index 14a41a243f7b..73657be84678 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -2796,6 +2796,8 @@ static inline void cpufreq_update_util(struct rq *rq, unsigned int flags) {}
#ifdef CONFIG_UCLAMP_TASK
unsigned long uclamp_eff_value(struct task_struct *p, enum uclamp_id clamp_id);
+unsigned long uclamp_transform_boost(unsigned long util, unsigned long uclamp_min,
+ unsigned long uclamp_max);
/**
* uclamp_rq_util_with - clamp @util with @rq and @p effective uclamp values.
@@ -2820,6 +2822,7 @@ unsigned long uclamp_rq_util_with(struct rq *rq, unsigned long util,
{
unsigned long min_util = 0;
unsigned long max_util = 0;
+ unsigned long clamp_util;
if (!static_branch_likely(&sched_uclamp_used))
return util;
@@ -2847,7 +2850,12 @@ unsigned long uclamp_rq_util_with(struct rq *rq, unsigned long util,
if (unlikely(min_util >= max_util))
return min_util;
- return clamp(util, min_util, max_util);
+ if (sysctl_sched_uclamp_min_to_boost)
+ clamp_util = uclamp_transform_boost(util, min_util, max_util);
+ else
+ clamp_util = clamp(util, min_util, max_util);
+
+ return clamp_util;
}
/*
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 272f4a272f8c..b3a83356a969 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -1827,6 +1827,15 @@ static struct ctl_table kern_table[] = {
.mode = 0644,
.proc_handler = sysctl_sched_uclamp_handler,
},
+ {
+ .procname = "sched_clamp_min2boost",
+ .data = &sysctl_sched_uclamp_min_to_boost,
+ .maxlen = sizeof(unsigned int),
+ .mode = 0644,
+ .proc_handler = proc_dointvec_minmax,
+ .extra1 = SYSCTL_ZERO,
+ .extra2 = SYSCTL_ONE,
+ },
#endif
#ifdef CONFIG_SCHED_AUTOGROUP
{
--
2.25.1
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