[Stgt-devel] Linux Kernel Version

Tom Tucker tom
Thu Jul 13 19:52:53 CEST 2006


I don't think you should merge it yet because the transport side hasn't
been tested yet. Will you have time at OLS to get together and
whiteboard a few design ideas (including the one I proposed) and discuss
the trade-offs?


On Fri, 2006-07-14 at 02:39 +0900, FUJITA Tomonori wrote:
> From: Tom Tucker <tom at opengridcomputing.com>
> Subject: Re: [Stgt-devel] Linux Kernel Version
> Date: Thu, 13 Jul 2006 10:00:33 -0500
> > > As you said, it's complicated to run tgt right now. I've been working
> > > on it because some people might be interested in tgt after OLS. I want
> > > to make sure that everyone can run tgt without effort. I'm in the
> > > middle of large user-space rewrite (I've commited some last night).
> > > 
> > > Sorry for delay about iSER tgt stuff. I will work on it after OLS. 
> > 
> > The biggest thing I'd like some guidance on is how we want to plug into
> > the transport switch. If connection management (not LOGIN, just the 
> > listen/accept paths), is pushed into the kernel, then the user-mode
> > code is insulated from the transport switch. This requires pushing the 
> > current TCP connection management into the kernel though and adding netlink 
> > messages for listen/accept. 
> > 
> > Otherwise, we need to replicate the switch in user-mode. The TCP tgt can
> > still use sockets in user mode, but he RDMA side will need to have the 
> > netlink messages anyway. The issue is that unlike a socket, the RDMA 
> > user-mode CM doesn't have the ability to have user-mode code and 
> > kernel-mode code both doing I/O on the transport like a socket. 
> > 
> > I've coded up the kernel-only approach, but haven't gotten much feedback 
> > on it, so I'm assuming that it's not the preferred method ;-)
> I guess that you are doing something like open-iscsi iSER code (the
> user-space daemon asks the kernel module to do transport staff, called
> endpoint in open-iscsi). It is fine by me. I will read your patch
> (really sorry about delay again) and merge it.
> > > If
> > > you guys teach me how to setup Chelsio T3 at OLS, I can work on it
> > > right after OLS. :)
> > 
> > Here's a How-To on bringing up the Chelsio code for RDMA
> Looks really helpful. Thanks. I'll try after OLS.

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