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    Subject[PATCH v2 1/4] iommu/arm-smmu-v3: Use command queue batching helpers to improve performance
    Date
    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@huawei.com>
    ---
    drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 6 ++++--
    1 file changed, 4 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..5eedb46aaceece8 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 +1747,17 @@ 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);

    + cmds.num = 0;
    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
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