linux-kernel - [PATCH 1/4] iommu/arm-smmu-v3: Use command queue batching helpers to improve performance

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Date:   Wed, 11 Aug 2021 19:48:49 +0800
From:   Zhen Lei <thunder.leizhen@...wei.com>
To:     Will Deacon <will@...nel.org>, Robin Murphy <robin.murphy@....com>,
        "Joerg Roedel" <joro@...tes.org>,
        linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
        iommu <iommu@...ts.linux-foundation.org>,
        <linux-kernel@...r.kernel.org>
CC:     Zhen Lei <thunder.leizhen@...wei.com>
Subject: [PATCH 1/4] iommu/arm-smmu-v3: Use command queue batching helpers to improve performance

The obvious key to the performance optimization of commit 587e6c10a7ce
("iommu/arm-smmu-v3: Reduce contention during command-queue insertion") is
to allow multiple cores to insert commands in parallel after a brief mutex
contention.

Obviously, inserting as many commands at a time as possible can reduce the
number of times the mutex contention participates, thereby improving the
overall performance. At least it reduces the number of calls to function
arm_smmu_cmdq_issue_cmdlist().

Therefore, use command queue batching helpers to insert multiple commands
at a time.

Signed-off-by: Zhen Lei <thunder.leizhen@...wei.com>
---
 drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
index 235f9bdaeaf223b..c81cd929047f573 100644
--- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
+++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
@@ -1747,15 +1747,16 @@ static int arm_smmu_atc_inv_master(struct arm_smmu_master *master)
 {
 	int i;
 	struct arm_smmu_cmdq_ent cmd;
+	struct arm_smmu_cmdq_batch cmds = {};
 
 	arm_smmu_atc_inv_to_cmd(0, 0, 0, &cmd);
 
 	for (i = 0; i < master->num_streams; i++) {
 		cmd.atc.sid = master->streams[i].id;
-		arm_smmu_cmdq_issue_cmd(master->smmu, &cmd);
+		arm_smmu_cmdq_batch_add(master->smmu, &cmds, &cmd);
 	}
 
-	return arm_smmu_cmdq_issue_sync(master->smmu);
+	return arm_smmu_cmdq_batch_submit(master->smmu, &cmds);
 }
 
 int arm_smmu_atc_inv_domain(struct arm_smmu_domain *smmu_domain, int ssid,
-- 
2.26.0.106.g9fadedd