linux-kernel - [PATCH v4 10/10] sched/topology: Use prebuilt SD flag degeneration mask

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Date:   Fri, 31 Jul 2020 12:55:02 +0100
From:   Valentin Schneider <valentin.schneider@....com>
To:     linux-kernel@...r.kernel.org
Cc:     Peter Zijlstra <peterz@...radead.org>, mingo@...nel.org,
        vincent.guittot@...aro.org, dietmar.eggemann@....com,
        morten.rasmussen@....com, Quentin Perret <qperret@...gle.com>
Subject: [PATCH v4 10/10] sched/topology: Use prebuilt SD flag degeneration mask

Leverage SD_DEGENERATE_GROUPS_MASK in sd_degenerate() and
sd_parent_degenerate(). The negation of SD_DEGENERATE_GROUPS_MASK is used
as the mask of flags not requiring groups, which is equivalent to
SD_WAKE_AFFINE, IOW is the same as what we have now.

Suggested-by: Peter Zijlstra <peterz@...radead.org>
Signed-off-by: Valentin Schneider <valentin.schneider@....com>
---
 kernel/sched/topology.c | 33 +++++++--------------------------
 1 file changed, 7 insertions(+), 26 deletions(-)

diff --git a/kernel/sched/topology.c b/kernel/sched/topology.c
index c6ecc395c76c..0cc5ce5cd034 100644
--- a/kernel/sched/topology.c
+++ b/kernel/sched/topology.c
@@ -160,22 +160,12 @@ static int sd_degenerate(struct sched_domain *sd)
 		return 1;
 
 	/* Following flags need at least 2 groups */
-	if (sd->flags & (SD_BALANCE_NEWIDLE |
-			 SD_BALANCE_WAKE |
-			 SD_BALANCE_FORK |
-			 SD_BALANCE_EXEC |
-			 SD_ASYM_PACKING |
-			 SD_SHARE_CPUCAPACITY |
-			 SD_ASYM_CPUCAPACITY |
-			 SD_SHARE_PKG_RESOURCES |
-			 SD_OVERLAP |
-			 SD_PREFER_SIBLING)) {
-		if (sd->groups != sd->groups->next)
-			return 0;
-	}
+	if ((sd->flags & SD_DEGENERATE_GROUPS_MASK) &&
+	    (sd->groups != sd->groups->next))
+		return 0;
 
 	/* Following flags don't use groups */
-	if (sd->flags & (SD_WAKE_AFFINE))
+	if (sd->flags & ~SD_DEGENERATE_GROUPS_MASK)
 		return 0;
 
 	return 1;
@@ -193,18 +183,9 @@ sd_parent_degenerate(struct sched_domain *sd, struct sched_domain *parent)
 		return 0;
 
 	/* Flags needing groups don't count if only 1 group in parent */
-	if (parent->groups == parent->groups->next) {
-		pflags &= ~(SD_BALANCE_NEWIDLE |
-			    SD_BALANCE_WAKE |
-			    SD_BALANCE_FORK |
-			    SD_BALANCE_EXEC |
-			    SD_ASYM_PACKING |
-			    SD_ASYM_CPUCAPACITY |
-			    SD_SHARE_CPUCAPACITY |
-			    SD_SHARE_PKG_RESOURCES |
-			    SD_OVERLAP |
-			    SD_PREFER_SIBLING);
-	}
+	if (parent->groups == parent->groups->next)
+		pflags &= ~SD_DEGENERATE_GROUPS_MASK;
+
 	if (~cflags & pflags)
 		return 0;
 
-- 
2.27.0