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Re: to_xfer_partial, qPart, and EOF
- From: Jim Blandy <jimb at red-bean dot com>
- To: gdb at sourceware dot org
- Date: Wed, 18 Jan 2006 17:18:49 -0800
- Subject: Re: to_xfer_partial, qPart, and EOF
- References: <20060118231837.GA17726@nevyn.them.org>
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.