Re: to_xfer_partial, qPart, and EOF

[Jim Blandy <jimb@red-bean.com>]

On 1/18/06, Daniel Jacobowitz <drow@false.org> wrote:
> I'm currently very well aware of the round trip latency in the remote
> protocol; it makes a huge difference over TCP, where larger packets are
> basically free up to a certain size, but round trips are very slow.  At
> the time he wanted to pursue this immediately; Andrew wanted to go without
> it for the moment, and it was never revisited.
>
> So that's action item one; I think it's time to add this.  So far so good.

This, and a few other remote protocol wrinkles, are consequences of
the mis-layering of the GDB protocol.  The protocol should simply
specify that the entire block of data gets transmitted, and let lower
layers handle retransmission and fragmentation.

I recognize it's probably not practical to fix this today, and maybe
it never will be.  But I keep running into instances of this when I
work on the remote protocol --- tracepoint definition packets needing
to be broken up into pieces to avoid long packets; breakpoint packets
needing to be idempotent, because they might be retransmitted; and so
on --- so I wanted to mention it.  Perhaps someone will have a flash
of super-coder powers some weekend.

> Any comments on either of these plans?  Otherwise I will probably implement
> them in the next couple of days.  I'm doing a lot of work in this area
> at present.

Sounds great to me.