linux-kernel - [PATCH v4 4/6] sched/fair: Provide update_sg_lb

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Date:   Tue, 10 Aug 2021 07:41:43 -0700
From:   Ricardo Neri <ricardo.neri-calderon@...ux.intel.com>
To:     "Peter Zijlstra (Intel)" <peterz@...radead.org>,
        Ingo Molnar <mingo@...nel.org>,
        Juri Lelli <juri.lelli@...hat.com>,
        Vincent Guittot <vincent.guittot@...aro.org>
Cc:     Srikar Dronamraju <srikar@...ux.vnet.ibm.com>,
        Nicholas Piggin <npiggin@...il.com>,
        Dietmar Eggemann <dietmar.eggemann@....com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Ben Segall <bsegall@...gle.com>, Mel Gorman <mgorman@...e.de>,
        Len Brown <len.brown@...el.com>,
        Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>,
        Tim Chen <tim.c.chen@...ux.intel.com>,
        Aubrey Li <aubrey.li@...ux.intel.com>,
        "Ravi V. Shankar" <ravi.v.shankar@...el.com>,
        Ricardo Neri <ricardo.neri@...el.com>,
        "Rafael J. Wysocki" <rafael.j.wysocki@...el.com>,
        Quentin Perret <qperret@...gle.com>,
        "Joel Fernandes (Google)" <joel@...lfernandes.org>,
        linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org,
        Ricardo Neri <ricardo.neri-calderon@...ux.intel.com>,
        Aubrey Li <aubrey.li@...el.com>,
        Daniel Bristot de Oliveira <bristot@...hat.com>
Subject: [PATCH v4 4/6] sched/fair: Provide update_sg_lb_stats() with sched domain statistics

Before deciding to pull tasks when using asymmetric packing of tasks,
on some architectures (e.g., x86) it is necessary to know not only the
state of dst_cpu but also of its SMT siblings. The decision to classify
a candidate busiest group as group_asym_packing is done in
update_sg_lb_stats(). Give this function access to the scheduling domain
statistics, which contains the statistics of the local group.

Cc: Aubrey Li <aubrey.li@...el.com>
Cc: Ben Segall <bsegall@...gle.com>
Cc: Daniel Bristot de Oliveira <bristot@...hat.com>
Cc: Dietmar Eggemann <dietmar.eggemann@....com>
Cc: Mel Gorman <mgorman@...e.de>
Cc: Quentin Perret <qperret@...gle.com>
Cc: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
Cc: Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>
Cc: Steven Rostedt <rostedt@...dmis.org>
Cc: Tim Chen <tim.c.chen@...ux.intel.com>
Reviewed-by: Joel Fernandes (Google) <joel@...lfernandes.org>
Reviewed-by: Len Brown <len.brown@...el.com>
Originally-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Signed-off-by: Ricardo Neri <ricardo.neri-calderon@...ux.intel.com>
---
Changes since v3:
  * None

Changes since v2:
  * Introduced this patch.

Changes since v1:
  * N/A
---
 kernel/sched/fair.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 3b686e18a39b..ae3d2bc59d8d 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -8539,6 +8539,7 @@ group_type group_classify(unsigned int imbalance_pct,
  * @sg_status: Holds flag indicating the status of the sched_group
  */
 static inline void update_sg_lb_stats(struct lb_env *env,
+				      struct sd_lb_stats *sds,
 				      struct sched_group *group,
 				      struct sg_lb_stats *sgs,
 				      int *sg_status)
@@ -8547,7 +8548,7 @@ static inline void update_sg_lb_stats(struct lb_env *env,
 
 	memset(sgs, 0, sizeof(*sgs));
 
-	local_group = cpumask_test_cpu(env->dst_cpu, sched_group_span(group));
+	local_group = group == sds->local;
 
 	for_each_cpu_and(i, sched_group_span(group), env->cpus) {
 		struct rq *rq = cpu_rq(i);
@@ -9110,7 +9111,7 @@ static inline void update_sd_lb_stats(struct lb_env *env, struct sd_lb_stats *sd
 				update_group_capacity(env->sd, env->dst_cpu);
 		}
 
-		update_sg_lb_stats(env, sg, sgs, &sg_status);
+		update_sg_lb_stats(env, sds, sg, sgs, &sg_status);
 
 		if (local_group)
 			goto next_group;
-- 
2.17.1