Re: RFC: Immediate data support for SRP

Bart Van Assche
2015-07-20T23:49:57Z

On 07/19/2015 02:25 PM, Vasiliy Tolstov wrote:
> > On 7/16/2015 6:25 PM, Bart Van Assche wrote:
> >> it is easy to add to the SRP initiator and target drivers.
> >> Implementations exist in the ib_srp-backport initiator driver and the
> >> SCST SRP target driver (see also
> >> https://github.com/bvanassche/ib_srp-backport and
> >> http://sourceforge.net/p/scst/svn/HEAD/tree/trunk/srpt/). These
> >> implementations are available since considerable time, work reliably,
> >> are backwards compatible and support zero-copy. Since using immediate
> >> data provides a measurable performance improvement I'm wondering whether
> >> it would be acceptable to add support for immediate data to the SRP
> >> drivers in the Linux kernel tree (ib_srp and ib_srpt) ?
>
> Does this possible in userspace? I'm working on software defined storage
> with rdma support,and I think this is usable.

Hello Vasiliy,

The feature of the RDMA API that was used to implement sending inline
data, namely passing a scatterlist to ib_post_send() with more than one
element, is also available in the user space RDMA API. I think it would
be easy to add inline data support in a user space implementation of
SRP. Not that it really matters, but your e-mail made me wonder whether
the source code of the user space SRP initiator implementation you are
working is available somewhere, and if so, under which license ?

Bart.