[gPXE] any negative implications of setting TCP window size to (65536 - 4) ?

[Joshua Oreman]

On Mon, Feb 1, 2010 at 11:50 PM, Marty Connor <mdc at etherboot.org> wrote:
>> On the other hand, we're probably safe bumping it to 256kB. Thoughts
>> from other developers?
>
> I think 256kB must be a typo because that's twice the heap size.  Did you
> mean 16KB or 24KB

Sorry, I meant increase the heap to 256kB. The TCP window size can't
go over 64kB because the window space is represented in a 16-bit
integer field.

> I have a suspicion (didn't look) that each connection is going to allocate
> this amount of memory, so with a lot of connections, things could get ugly
> real fast.  Put 3 NICs in a machine with those settings, and let's see what
> happens when they all meed to do DHCP :)

The memory is not allocated statically; it'll only come into play if
all three connections actually have to buffer 64kB of data because
they're receiving it so fast. Since gPXE generally only has one
connection actively working at a time, I doubt this will be a big
problem for us.

DHCP is UDP, so the TCP window size doesn't come into play.

-- Josh