Public bug reported:
[Impact]
There's a significant performance gain to be had by removing the need to flush
the IOMMU TLB on every unmap. I'm seeing a 25% performance gain w/ fio reads on
a single NVMe device. This mode of operation is available for x86 via the
"intel_iommu=strict" parameter. This support is now available upstream for ARM
platforms via the "iommu.strict=[0|1]" parameter, while keeping the default in
strict mode.
[Test Case]
$ cat fio.rc
[global]
rw=read
direct=1
ioengine=libaio
iodepth=2048
numjobs=10
bs=4k
group_reporting=1
group_reporting=1
cpumask=0xff
runtime=100
loops = 10000
[job1]
filename=/dev/nvme0n1
[Fix]
44f6876a00e83 iommu/arm-smmu: Support non-strict mode
b2dfeba654cb0 iommu/io-pgtable-arm-v7s: Add support for non-strict mode
9662b99a19abc iommu/arm-smmu-v3: Add support for non-strict mode
b6b65ca20bc93 iommu/io-pgtable-arm: Add support for non-strict mode
68a6efe86f6a1 iommu: Add "iommu.strict" command line option
2da274cdf998a iommu/dma: Add support for non-strict mode
07fdef34d2be6 iommu/arm-smmu-v3: Implement flush_iotlb_all hook
85c7a0f1ef624 iommu/io-pgtable-arm: Fix race handling in split_blk_unmap()
[Regression Risk]
** Affects: linux (Ubuntu)
Importance: Undecided
Assignee: dann frazier (dannf)
Status: In Progress
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https://bugs.launchpad.net/bugs/1806488
Title:
Support non-strict iommu mode on arm64
Status in linux package in Ubuntu:
In Progress
Bug description:
[Impact]
There's a significant performance gain to be had by removing the need to
flush the IOMMU TLB on every unmap. I'm seeing a 25% performance gain w/ fio
reads on a single NVMe device. This mode of operation is available for x86 via
the "intel_iommu=strict" parameter. This support is now available upstream for
ARM platforms via the "iommu.strict=[0|1]" parameter, while keeping the default
in strict mode.
[Test Case]
$ cat fio.rc
[global]
rw=read
direct=1
ioengine=libaio
iodepth=2048
numjobs=10
bs=4k
group_reporting=1
group_reporting=1
cpumask=0xff
runtime=100
loops = 10000
[job1]
filename=/dev/nvme0n1
[Fix]
44f6876a00e83 iommu/arm-smmu: Support non-strict mode
b2dfeba654cb0 iommu/io-pgtable-arm-v7s: Add support for non-strict mode
9662b99a19abc iommu/arm-smmu-v3: Add support for non-strict mode
b6b65ca20bc93 iommu/io-pgtable-arm: Add support for non-strict mode
68a6efe86f6a1 iommu: Add "iommu.strict" command line option
2da274cdf998a iommu/dma: Add support for non-strict mode
07fdef34d2be6 iommu/arm-smmu-v3: Implement flush_iotlb_all hook
85c7a0f1ef624 iommu/io-pgtable-arm: Fix race handling in split_blk_unmap()
[Regression Risk]
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