Public bug reported:
[Impact]
With SMMU page translation mode enabled. Several inefficiencies on ARM SMMUv3
driver has been identified. As a result IO BW is severely impacted.
[Test]
Running iperf on mellanox Connect-x4 cards capable of doing 40Gbps BW connected
back to back we get only about 15Gbps.
iperf -c 192.168.5.5 --bind 192.168.5.10 -P 5 -w 3.1M
------------------------------------------------------------
Client connecting to 192.168.5.5, TCP port 5001
Binding to local address 192.168.5.10
TCP window size: 6.20 MByte (WARNING: requested 3.10 MByte)
------------------------------------------------------------
[ 7] local 192.168.5.10 port 42588 connected with 192.168.5.5 port 5001
[ 3] local 192.168.5.10 port 42582 connected with 192.168.5.5 port 5001
[ 5] local 192.168.5.10 port 42584 connected with 192.168.5.5 port 5001
[ 4] local 192.168.5.10 port 42586 connected with 192.168.5.5 port 5001
[ 6] local 192.168.5.10 port 42590 connected with 192.168.5.5 port 5001
[ ID] Interval Transfer Bandwidth
[ 3] 0.0-10.0 sec 6.50 GBytes 5.58 Gbits/sec
[ 4] 0.0-10.0 sec 1.81 GBytes 1.56 Gbits/sec
[ 6] 0.0-10.0 sec 6.08 GBytes 5.22 Gbits/sec
[ 7] 0.0-10.0 sec 1.99 GBytes 1.71 Gbits/sec
[ 5] 0.0-10.0 sec 2.00 GBytes 1.72 Gbits/sec
[SUM] 0.0-10.0 sec 18.4 GBytes 15.8 Gbits/sec
[Fix]
After applying the patches listed below from linux-next, we were able to get
throughputs of 35+ Gbps. These patches are currently in linux-next and in line
for 4.13-rc.
iommu/io-pgtable-arm: Use dma_wmb() instead of wmb() when publishing table
iommu/arm-smmu-v3: Remove io-pgtable spinlock
iommu/arm-smmu: Remove io-pgtable spinlock
iommu/io-pgtable-arm-v7s: Support lockless operation
iommu/io-pgtable-arm: Support lockless operation
iommu/io-pgtable: Introduce explicit coherency
iommu/io-pgtable-arm-v7s: Refactor split_blk_unmap
iommu/io-pgtable-arm: Improve split_blk_unmap
iommu/io-pgtable-arm-v7s: Check table PTEs more precisely
iommu/io-pgtable-arm-v7s: constify dummy_tlb_ops.
iommu/io-pgtable-arm-v7s: Check for leaf entry before dereferencing it
iommu/io-pgtable-arm-v7s: Add support for the IOMMU_PRIV flag
iommu/io-pgtable-arm: Avoid shift overflow in block size
iommu/io-pgtable-arm: Check for leaf entry before dereferencing it
iommu/io-pgtable-arm: add support for the IOMMU_PRIV flag
iommu: add IOMMU_PRIV attribute
[Regression Potential]
These patches cherry-pick cleanly ontop of Zesty (4.10), and the patches are
limited to ARM SMMU and pagetable fixes. The patches were tested on QDF2400
system with mlx connect-X4 40G cards.
** Affects: linux (Ubuntu)
Importance: Critical
Assignee: Manoj Iyer (manjo)
Status: Incomplete
** Tags: qdf2400 zesty
** Summary changed:
- [Zesty] Fixes to smmuv3 on ARM64
+ [Zesty] Fixes to smmuv3 and io-pgtable on ARM64
** Summary changed:
- [Zesty] Fixes to smmuv3 and io-pgtable on ARM64
+ [Zesty] Fixes to iommu on arm64 to improve IO performance
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https://bugs.launchpad.net/bugs/1705123
Title:
[Zesty] Fixes to iommu on arm64 to improve IO performance
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