Jeff, I have back-ported patches to address "Support SMMU passthrough using the default domain". This adds a new kernel command line option iommu.passthrough=0/1 to Configure DMA to bypass the IOMMU for ARM64. http://bugs.launchpad.net/bugs/1688158
0 - Use IOMMU translation for DMA. 1 - Bypass the IOMMU for DMA. The test case recommended by Nate using 'fio' is: $ sudo apt update ; sudo apt install fio $ sudo fio --name=global --readonly --group_reporting --direct=1 --ioengine=libaio --rw=read --eta-newline=1s --size=1T --blocksize=512k --iodepth=32 --numjobs=1 --runtime=10s --name=nvme_0 --filename=/dev/nvme0n1 You can find the kernel and the instructions to install the kernel in the Centriq test PPA: https://launchpad.net/~centriq-team/+archive/ubuntu/test/ Nate and I have gone back and forth on testing these patches and finally came down to having this test run on an NVME device. Unfortunately I cant seem to find any nvme HW at this time, we would need to order these drive and could take time. Could you please test the kernel using the test case mentioned above and reply back to this email with test case out put for both cases. iommu.passthrough=0 and iommu.passthrough=1. We should see better performance (iops may be) with IOMMU bypassed for DMA (ie iommu.passthrough=1). The bug is cced on this email, so if you replay with a summary output in both cases it will be automatically recorded in the bug. Once I get your test results I will be able to make a case for SRUing these patches. Thanks a ton Manoj Iyer -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1688158 Title: [SRU][Zesty] Support SMMU passthrough using the default domain To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1688158/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
