Just FYI, it will likely take me a few days to get to this. Jeffrey Hugo Senior Engineer Qualcomm Datacenter Technologies, Inc. 1-303-247-5002
From: Manoj Iyer [mailto:manoj.i...@canonical.com] Sent: Thursday, May 11, 2017 9:23 PM To: Jeff Hugo <jh...@qti.qualcomm.com>; 1688...@bugs.launchpad.net Cc: Nate Watterson <nwatt...@qti.qualcomm.com>; Timur Tabi <ti...@qti.qualcomm.com> Subject: [Bug #1688158] Please help test kernel for iommu.passthrough=0/1 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 Kernel Packages, which is subscribed to linux in Ubuntu. https://bugs.launchpad.net/bugs/1688158 Title: [SRU][Zesty] Support SMMU passthrough using the default domain Status in linux package in Ubuntu: Incomplete Bug description: [Impact] Have the SMMU come up in a passthrough configuration, and then allow subsequent translation for things such as VFIO. Rather than do this in each SMMU driver, it's much cleaner to allow the default domain to be configured to be something other than DMA. This patch series implements a command-line option to configure the default domain type. Currently, it supports "dma" and "identity" which is sufficient for the passthrough use-case. [Fix] The following patch series in linux-next adds this support to the kernel. 4a8d8a14c0d0 arm64: dma-mapping: Only swizzle DMA ops for IOMMU_DOMAIN_DMA fccb4e3b8ab0 iommu: Allow default domain type to be set on the kernel command line beb3c6a066bf iommu/arm-smmu-v3: Install bypass STEs for IOMMU_DOMAIN_IDENTITY domains 67560edcd8e5 iommu/arm-smmu-v3: Make arm_smmu_install_ste_for_dev return void 61bc671179f1 iommu/arm-smmu: Install bypass S2CRs for IOMMU_DOMAIN_IDENTITY domains 0834cc28fa56 iommu/arm-smmu: Restrict domain attributes to UNMANAGED domains To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1688158/+subscriptions -- Mailing list: https://launchpad.net/~kernel-packages Post to : kernel-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~kernel-packages More help : https://help.launchpad.net/ListHelp
