Re: [PATCH 1/4] iommu/arm-smmu-v3: Use command queue batching helpers to improve performance
From: Robin Murphy <robin.murphy@arm.com>
Date: 2021-08-13 16:01:46
Also in:
linux-iommu, lkml
On 2021-08-11 12:48, Zhen Lei wrote:
quoted hunk ↗ jump to hunk
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 <redacted> --- 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 = {};
BTW, it looks like this has crossed over with John's patch removing these. Robin.
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,_______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel