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Message-Id: <eba3303cdab63e2d96dcc630d153004e4afb88f3.1754712565.git.tim.c.chen@linux.intel.com>
Date: Sat, 9 Aug 2025 13:07:23 +0800
From: Chen Yu <yu.c.chen@...el.com>
To: Peter Zijlstra <peterz@...radead.org>,
Ingo Molnar <mingo@...hat.com>,
K Prateek Nayak <kprateek.nayak@....com>,
"Gautham R . Shenoy" <gautham.shenoy@....com>
Cc: Vincent Guittot <vincent.guittot@...aro.org>,
Juri Lelli <juri.lelli@...hat.com>,
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>,
Libo Chen <libo.chen@...cle.com>,
Madadi Vineeth Reddy <vineethr@...ux.ibm.com>,
Hillf Danton <hdanton@...a.com>,
Shrikanth Hegde <sshegde@...ux.ibm.com>,
Jianyong Wu <jianyong.wu@...look.com>,
Yangyu Chen <cyy@...self.name>,
Tingyin Duan <tingyin.duan@...il.com>,
Vern Hao <vernhao@...cent.com>,
Len Brown <len.brown@...el.com>,
Tim Chen <tim.c.chen@...ux.intel.com>,
Aubrey Li <aubrey.li@...el.com>,
Zhao Liu <zhao1.liu@...el.com>,
Chen Yu <yu.chen.surf@...il.com>,
Chen Yu <yu.c.chen@...el.com>,
linux-kernel@...r.kernel.org
Subject: [RFC PATCH v4 19/28] sched: Introduce SCHED_CACHE_LB to control cache aware load balance
From: Tim Chen <tim.c.chen@...ux.intel.com>
Introduce the SCHED_CACHE_LB sched feature to enable or disable
cache aware load balance in the schduler.
Co-developed-by: Chen Yu <yu.c.chen@...el.com>
Signed-off-by: Chen Yu <yu.c.chen@...el.com>
Signed-off-by: Tim Chen <tim.c.chen@...ux.intel.com>
---
kernel/sched/fair.c | 18 ++++++++++--------
kernel/sched/features.h | 1 +
2 files changed, 11 insertions(+), 8 deletions(-)
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 22b7a7fe538e..9843d4e1d84f 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -10019,7 +10019,7 @@ int can_migrate_task(struct task_struct *p, struct lb_env *env)
return 1;
#ifdef CONFIG_SCHED_CACHE
- if (sched_feat(SCHED_CACHE) &&
+ if (sched_feat(SCHED_CACHE) && sched_feat(SCHED_CACHE_LB) &&
get_migrate_hint(env->src_cpu, env->dst_cpu, p) == mig_forbid)
return 0;
#endif
@@ -10105,7 +10105,7 @@ static struct list_head
LIST_HEAD(no_pref_llc);
LIST_HEAD(pref_other_llc);
- if (!sched_feat(SCHED_CACHE))
+ if (!sched_feat(SCHED_CACHE) || !sched_feat(SCHED_CACHE_LB))
return tasks;
if (cpus_share_cache(env->dst_cpu, env->src_cpu))
@@ -10290,7 +10290,8 @@ static int detach_tasks(struct lb_env *env)
* The tasks have already been sorted by order_tasks_by_llc(),
* they are tasks that prefer the current LLC.
*/
- if (sched_feat(SCHED_CACHE) && p->preferred_llc != -1 &&
+ if (sched_feat(SCHED_CACHE) && sched_feat(SCHED_CACHE_LB) &&
+ p->preferred_llc != -1 &&
llc_id(env->src_cpu) == p->preferred_llc)
break;
#endif
@@ -10947,7 +10948,7 @@ static inline bool llc_balance(struct lb_env *env, struct sg_lb_stats *sgs,
struct sched_domain *child = env->sd->child;
int llc;
- if (!sched_feat(SCHED_CACHE))
+ if (!sched_feat(SCHED_CACHE) || !sched_feat(SCHED_CACHE_LB))
return false;
if (env->sd->flags & SD_SHARE_LLC)
@@ -11058,7 +11059,8 @@ static void update_sg_if_llc(struct lb_env *env, struct sg_lb_stats *sgs,
struct sched_domain *sd = env->sd->child;
struct sched_domain_shared *sd_share;
- if (!sched_feat(SCHED_CACHE) || env->idle == CPU_NEWLY_IDLE)
+ if (!sched_feat(SCHED_CACHE) || env->idle == CPU_NEWLY_IDLE ||
+ !sched_feat(SCHED_CACHE_LB))
return;
/* only care the sched domain that spans 1 LLC */
@@ -11120,7 +11122,7 @@ static inline void update_sg_lb_stats(struct lb_env *env,
*sg_overutilized = 1;
#ifdef CONFIG_SCHED_CACHE
- if (sched_feat(SCHED_CACHE)) {
+ if (sched_feat(SCHED_CACHE) && sched_feat(SCHED_CACHE_LB)) {
int j;
for (j = 0; j < max_llcs; ++j)
@@ -12406,7 +12408,7 @@ imbalanced_active_balance(struct lb_env *env)
static inline bool
break_llc_locality(struct lb_env *env)
{
- if (!sched_feat(SCHED_CACHE))
+ if (!sched_feat(SCHED_CACHE) || !sched_feat(SCHED_CACHE_LB))
return 0;
if (cpus_share_cache(env->src_cpu, env->dst_cpu))
@@ -12908,7 +12910,7 @@ static int active_load_balance_cpu_stop(void *data)
#ifdef CONFIG_SCHED_CACHE
int llc = llc_idx(target_cpu);
- if (!sched_feat(SCHED_CACHE))
+ if (!sched_feat(SCHED_CACHE) || !sched_feat(SCHED_CACHE_LB))
goto out_unlock;
if (llc < 0)
diff --git a/kernel/sched/features.h b/kernel/sched/features.h
index d2af7bfd36bf..11dbd74cd365 100644
--- a/kernel/sched/features.h
+++ b/kernel/sched/features.h
@@ -88,6 +88,7 @@ SCHED_FEAT(TTWU_QUEUE, true)
SCHED_FEAT(SIS_UTIL, true)
SCHED_FEAT(SCHED_CACHE, true)
+SCHED_FEAT(SCHED_CACHE_LB, true)
/*
* Issue a WARN when we do multiple update_rq_clock() calls
* in a single rq->lock section. Default disabled because the
--
2.25.1
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