linaro Committee Confidential @ 2017

SFO17-320 TSC Accelerators Discussion

David A RuslingFrancois, Martin

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linaro Committee Confidential @ 2017

Overview● Current hardware acceleration work in Linaro (and elsewhere)

○ LNG○ LEG

● Discussion ○ Are any activities common (or should any activities be common?)○ Anything missing?

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LNG perspective● Use cases

○ Cloud RAN: matrix compression on FPGA○ Mobile Edge computing: Video acceleration○ CPE (enterprise or consumer): IPsec acceleration

● Solutions needed○ Linux kernel

■ complex to add because of crash risks and hence upstream delays (if accepted)■ Required latencies are such that “one size fits all” kernel approach do not meet performance

○ Userland■ Diverse ways to match performance goals and bug containment (as opposed to kernel crash)■ Not a Linux first class citizen, security issues because not using IOMMUs

● Vision○ Stop kernel bypass, start kernel driver cooperation: secure userland direct dataplane IO○ Linux kernel: always in charge of IO controlplane○ Movement started

■ vfio_mdev for virtio-gpu■ Mellanox libiverbs DPDK PMD on bifurcated drivers■ LNG: vf-netdev for ODP, DPDK, Netmap, Zephyr...

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LNG activities● Mimic OpenVPN: IPsec acceleration with tap interface

○ Transparent to Linux and applications○ Huge efficiency benefits (1 A53 core + IPsec HW to deal with 20Gbps IMIX)

■ Can handle fat pipes■ 5x less expensive per secured Gbps that ANY other solution

○ Plan to be delivered as a LEG ERP 2018.1 package and other forms■ Strongswan? OpenVPN for the IPsec ESP tunnel? ENEA Linux?

● net_mdev○ Leverage VFIO to expose queues (and only queues) to userland○ Prototyping, checking relationship with other technologies (WrapDrive, dma_buf, Netmap)

● virtio-fpga○ Implement ETSI NFV IFA002 specifications

■ Standard load of bitstream through virtio-fpga -> obtain passthrough device on the fly■ Leverage that device directly■ May be create classes of passthrough devices (network…)

○ Current status: positive industry contacts, public support from Cisco, Ericsson, Nokia○ Not limited to LNG very broad use cases

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Coherent acceleration● Technologies: Arm: CCIX, Intel: PPC: CAPI/CCIX● Radical change of IO model, even if it does look like it● If drivers don’t evolve (metadata for IO…) most of benefits will be lost● New model is about cacheline movement control which means in-depth

understanding of cache coherency protocol by developers● peer to peer connectivity to chain accelerators and IOMMU relationship is very

unknown at this stage○ PCIe Access Control Services (ACS) was created to solve this on PCIe

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LMG Accelerator Interest● Mobile Tensorflow

○ https://www.tensorflow.org/mobile/○ “makes sense when there is a poor or missing network connection, or where sending

continuous data to a server would be too expensive”● Use case

○ Image processing/identification is a common use case○ Voice input

● Vulkan, OpenCL-next ○ Vulkan is strategic (part of AOSP)○ OpenCL hasn’t seen adoption by handset vendors○ Is the merging of Vulkan & OpenCL-next what the ARM ecosystem needs

linaro Committee Confidential @ 2017

Thank You

#SFO17BUD17 keynotes and videos on: connect.linaro.orgFor further information: www.linaro.org

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