[dpdk-dev] bifurcated driver
Zhou, Danny
danny.zhou at intel.com
Wed Nov 5 23:48:34 CET 2014
Hi Thomas,
Thanks for sharing the links to ibverbs, I will take a close look at it and compare it to bifurcated driver. My take
after a rough review is that idea is very much similar, but bifurcated driver implementation is generic for any
Ethernet device based on existing af_packet mechanism, with extension of exchanging the messages between
user space and kernel space driver.
I have an internal document to summary the pros and cons of below solutions, except for ibvers, but
will be adding it shortly.
- igb_uio
- uio_pci_generic
- VFIO
- bifurcated driver
Short answers to your questions:
> - upstream status
Adding IOMMU based memory protection and generic descriptor description support now, into version 2
kernel patches.
> - usable with kernel netdev
af_packet based, and relevant patchset will be submitted to netdev for sure.
> - usable in a vm
No, it does no coexist with SRIOV for number of reasons. but if you pass-through a PF to a VM, it works perfect.
> - usable for Ethernet
It could work with all Ethernet NICs, as flow director is available and NIC driver support new net_ops to split off
queue pairs for user space.
> - hardware requirements
No specific hardware requirements. All mainstream NICs have multiple qpairs and flow director support.
> - security protection
Leverage IOMMU to provide memory protection on Intel platform. Other archs provide similar memory protection
mechanism, so we only use arch-agnostic DMA memory allocation APIs in kernel to support memory protection.
> - performance
DPDK native performance on user space queues, as long as drop_en is enabled to avoid head-of-line blocking.
-Danny
> -----Original Message-----
> From: Thomas Monjalon [mailto:thomas.monjalon at 6wind.com]
> Sent: Wednesday, November 05, 2014 9:01 PM
> To: Zhou, Danny
> Cc: dev at dpdk.org; Fastabend, John R
> Subject: Re: [dpdk-dev] bifurcated driver
>
> Hi Danny,
>
> 2014-10-31 17:36, O'driscoll, Tim:
> > Bifurcated Driver (Danny.Zhou at intel.com)
>
> Thanks for the presentation of bifurcated driver during the community call.
> I asked if you looked at ibverbs and you wanted a link to check.
> The kernel module is here:
> http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/drivers/infiniband/core
> The userspace library:
> http://git.kernel.org/cgit/libs/infiniband/libibverbs.git
>
> Extract from Kconfig:
> "
> config INFINIBAND_USER_ACCESS
> tristate "InfiniBand userspace access (verbs and CM)"
> select ANON_INODES
> ---help---
> Userspace InfiniBand access support. This enables the
> kernel side of userspace verbs and the userspace
> communication manager (CM). This allows userspace processes
> to set up connections and directly access InfiniBand
> hardware for fast-path operations. You will also need
> libibverbs, libibcm and a hardware driver library from
> <http://www.openfabrics.org/git/>.
> "
>
> It seems to be close to the bifurcated driver needs.
> Not sure if it can solve the security issues if there is no dedicated MMU
> in the NIC.
>
> I feel we should sum up pros and cons of
> - igb_uio
> - uio_pci_generic
> - VFIO
> - ibverbs
> - bifurcated driver
> I suggest to consider these criterias:
> - upstream status
> - usable with kernel netdev
> - usable in a vm
> - usable for ethernet
> - hardware requirements
> - security protection
> - performance
>
> --
> Thomas
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