Messages in this thread | | | Subject | Re: [ofa-general] Re: [PATCH RFC] RDMA/CMA: Allocate PS_TCP ports from the host TCP port space. | From | Roland Dreier <> | Date | Fri, 17 Aug 2007 12:52:39 -0700 |
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> > Isn't RDMA _part_ of the "software net stack" within Linux?
> It very much is not so.
This is just nit-picking. You can draw the boundary of the "software net stack" wherever you want, but I think Sean's point was just that RDMA drivers already are part of Linux, and we all want them to get better.
> When using RDMA you lose the capability to do packet shaping, > classification, and all the other wonderful networking facilities > you've grown to love and use over the years.
Same thing with TSO and LRO and who knows what else. I know you're going to make a distinction between "stateless" and "stateful" offloads, but really it's just an arbitrary distinction between things you like and things you don't.
> Imagine if you didn't know any of this, you purchase and begin to > deploy a huge piece of RDMA infrastructure, you then get the mandate > from IT that you need to add firewalling on the RDMA connections at > the host level, and "oh shit" you can't?
It's ironic that you bring up firewalling. I've had vendors of iWARP hardware tell me they would *love* to work with the community to make firewalling work better for RDMA connections. But instead we get the catch-22 of your changing arguments -- first, you won't even consider changes that might help RDMA work better in the name of maintainability; then you have to protect poor, ignorant users from accidentally using RDMA because of some problem or another; and then when someone tries to fix some of the problems you mention, it's back to step one.
Obviously some decisions have been prejudged here, so I guess this moves to the realm of politics. I have plenty of interesting technical stuff, so I'll leave it to the people with a horse in the race to find ways to twist your arm.
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