Simplified iWARP Consumer Library

Dear all,

as announced last week (on [email protected]), I have developed a shared library to simplify iWARP/RDMA application development on Linux in the course of my PhD. The library, called libiwarp, is based on libibverbs and librdmacm - it is essentially a set of wrappers to hide some of the complexity.

Upon request, I hereby post the source code of the library (libiwarp) as well as a sample application that demonstrates the usage (libiwarp_sample_app). After having extracted the tarball, change to the libiwarp directory where you will find a README file explaining the installation and giving an overview of the library.

I would be very interested in your feedback! Also, if you have any questions, please do not hesitate to contact me.

Best regards,
Philip

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Philip Frey
Systems Group, Dept. of Computer Science Swiss Federal Institute of Technology (ETH), Zurich CH-8092 Zurich/Switzerland [email protected]

The general list isn't functional since last fall, as of such, your announcement wasn't seen by any of the non directly CCed recipients... can you please resend it here ([email protected])?

Or.

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Dear all,

I was made aware of the fact that the [email protected] mailinglist was deprecated and that my initial post about the iWARP library did not reach you. (The general list is still linked on openfabrics.org without a notice of it being deprecated.)

Please, find below a copy of the original message.

"Dear all,

throughout the course of my PhD, I have written a number of user applications based on the OFED verbs. After some time, I realized that many programming tasks are repetitive (particularly the connection management) and started to wrap them.

This eventually led to a slim, shared library called libiwarp which includes all the basic primitives of RDMA-based communication, implemented as wrappers around libibverbs. Throughout various research projects, the library has turned out to be quite useful especially for people who are not familiar with all the details of the OFED verbs (like master students that only have 6 months to complete their projects or people that simply want to play around with iWARP and run a few simple tests).

We have shown, by experiment, that the overhead induced by the wrappers is negligible, yet it simplifies writing RDMA-based applications significantly. Furthermore, as the library does not replace the OFED verbs, it does not impose any restrictions with regard to the original functionality. Whenever there is something missing in the libiwarp, you can always use the interface provided by the OFED verbs.

As I am now in the process of finishing my work, I was wondering whether there is an interest in the OpenFabrics community for such a library which provides a simplified interface for the OFED verbs. If there is, I would be glad to share my source code with you.

Many thanks for your consideration and best regards,
Philip"

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I briefly toured through the code, and it seems to offer these main features:

1. Joins the rdma_cm_id and qp together into a single construct.
2. Supports synchronous rdma_cm operation.
3. Abstracts some initialization, like opening the device, creating PDs, etc.
4. Simplifies some verbs operations.

Would it be possible to submit patches against the librdmacm to integrate some of these features?

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I'll have to look into that. So far, the library was intended as an add-on to the existing code with the option to fall back to the original API if need be.

Which of the features would you want to see in librdmacm? I guess the integration of the cm_id and qp as well as the simpler (synchronous) connection establishment and teardown functionality would fit. However, all cm events will thereafter be handled within the library rather than being presented to the user. Does that make sense?

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I think we keep this concept.

I wasn't thinking about replacing existing calls, but rather adding new functions. I would start with just trying to integrate one feature, probably the simpler connection model for the active side, then look to expand from there.

- Sean

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I have some ideas for simplifying connection establishment as part of my changes to support native IB addresses through the rdma_cm interface. This includes adding new calls to the librdmacm: rdma_getaddrinfo and rdma_create_id_and_optional_qp_and_bind_addr_and_set_route.
I'll pick a different name for the latter. :) Combined, I think these calls could allow a user to more easily connect, while still providing low level control for anyone who wants it.

I haven't looked at the details for this, but we may be able to support synchronous operation by allowing the user to provide a NULL rdma_event_channel when creating the rdma_cm_id. We can take advantage of rdma_migrate_id to implement this, or even toggle between synchronous and asynchronous mode. The hope is that the librdmacm can remain threadless.

If you can give me a month or so to finish my current patches, I'll take a look at this as part of my work.

- Sean

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