RE: [EXPERIMENTAL v1 0/4] RDMA loopback device

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 




> -----Original Message-----
> From: Leon Romanovsky <leon@xxxxxxxxxx>
> Sent: Wednesday, February 27, 2019 1:56 AM
> To: Parav Pandit <parav@xxxxxxxxxxxx>
> Cc: bvanassche@xxxxxxx; linux-rdma@xxxxxxxxxxxxxxx
> Subject: Re: [EXPERIMENTAL v1 0/4] RDMA loopback device
> 
> On Wed, Feb 27, 2019 at 12:27:13AM -0600, Parav Pandit wrote:
> > This patchset adds RDMA loopback driver.
> > Initially for RoCE which works on lo netdevice.
> >
> > It is tested with with nvme fabrics over ext4, perftests, and rping.
> > It only supports RC and GSI QPs.
> > It supports only RoCEv2 GIDs which belongs to loopback lo netdevice.
> >
> > It is only posted for discussion [1].
> > It is not yet ready for RFC posting or merge.
> 
> Which type of discussion do you expect?
Continuation of [1].
> And can you give brief explanation why wasn't enough to extend rxe/siw?
> 
Adding lo netdev to rxe is certainly an option along with cma patch in this series.

qp state machine is around spin locks..
pools doesn't use xarray that loopback uses and siw intends to use.

Incidentally, 5.0.0.rc5 rxe crashes on registering memory. Didn't have inspiration to supply a patch.

However rxe as it stands today after several fixes from many is still not there.
It leaks consumer index to user space and not sure its effect of it. Jason did talk some of the security concern I don't recall.
A while back when I reviewed the code, saw things that might crash kernel.

Users complain of memory leaks, rnr retries dropping connections..

Giving low priority to most of them, I think desire to have loopback rdma device are below.
1. rxe is not ready for adding IB link types and large code restructure to avoid skb processing in it. Pretty large rewrite to skip skbs.
2. stability and reasonable performance
3. maintainability

But if you think rxe is solid, siw should refactor the rxe code and start using most pieces from there, split into library for roce and iw.
Once that layering is done, may be loopback can fit that as different L4 so that rxe uses skb, siw uses sockets, loopback uses memcpy.

Loopback's helper.c is intended to share code with siw for table resources as xarray.
It also offers complete kernel level handling of data and control path commands and published perf numbers.




[Index of Archives]     [Linux USB Devel]     [Video for Linux]     [Linux Audio Users]     [Photo]     [Yosemite News]     [Yosemite Photos]     [Linux Kernel]     [Linux SCSI]     [XFree86]

  Powered by Linux