[mosh-devel] Lazy buffers?

[Robert Redelmeier]

  Success!  (Thanks for the tip about debian/control).

-b lowbandwith has the delays I suggested.  --predict=[DEFAULT]
and sightly better --predict=experimental  give that neat underlining
that disappears and fixes itself when wrong (like vim k for scroll up).

Horizontal cursor <- and -> work fine, without delays (or at least
working on the buffer).  But vertical scrolling has maddening delays
and slow visual feedback.  Hard to correctly position cursor.

-- Robert


On 1657-0700 Tue 21 Apr, Keith Winstein wrote in part:
> Can you give a try to the lowbandwidth branch with the
> --predict=experimental command-line option? You might find that
> to be more to your liking.
> 
> We could flush out on certain characters -- that would be reasonable (but
> not currently implemented).
> 
> Cheers,
> Keith
> 
> On Tue, Apr 21, 2015 at 4:49 PM, Robert Redelmeier <redelm at sbcglobal.net>
> wrote:
> 
> > On 0022-0700 Tue 21 Apr, Keith Winstein wrote in part:
> > > Hello Robert, Thanks for your email!
> >
> > And thank you in turn for your prompt and detailed reply.
> >
> > > We do this to a degree,
> > > but with the goal of _reducing_ latency -- please see Figure
> > > 3 of the Mosh paper ( https://mosh.mit.edu/mosh-paper.pdf).
> >
> > Fascinating!  This 8ms is far too fast for human input, could
> > it be something like ACK & echo packet combining, or combining
> > from terminal local [cut'n']paste?
> >
> > > With the constants tuned differently, we end up reducing the
> > > packets sent as you suggest. This is in the "lowbandwidth"
> > > branch in the Git repository.  > > Cheers, > Keith
> >
> > I had a peek, thanks, but could not see how this would work
> > differently from termios.c_cc(VTIME)=5 beyond ^C handling.  I tried
> > this dumb delay, and the added latency on top of a slow connection
> > was very irksome.  But I found I could reduce the irritation greatly
> > by forcing the buffer out early when a command char was received.
> > Could the special handling for ^C be expanded to all ^char plus
> > duplicated chars (many pgms use hjkl for cursor movement)?
> >
> > Latency during straight typing is far less annoying unless chars
> > are lost.  Of course this system generates lots of false flushes.
> > But who cares?  Even `bookkeepers` sent as 4 packets is much better
> > than 11, especially considering the "ACK-echo-ACK" multiplication.
> >
> >
> > > On Mon, Apr 20, 2015 at 6:00 PM, Robert Redelmeier <redelm at sbcglobal.net
> > >
> > > wrote:
> > >
> > > >  First, thanks y'all for your work on mosh!
> > > > Second, a suggestion for your consideration (_NOT_ a vile "feature
> > > > request"):
> > > >
> > > > Have you considered allowing send buffers to fill a bit before
> > > > sending?  Not sending ASAP, but often sending more than one char
> > > > per packet?  Of course this increases latency, but reduces packet
> > > > count _tremendously_ and data usage likewise since the payload is
> > > > tiny compared to overhead (incl ACK)..
> > > >
> > > > Not sure how this would interact with SSP, but I hacked ssh to do
> > > > this 10+ years ago.  To minimize the latency when it would most
> > > > annoy, the buffer was released if a command was received or when
> > > > typing stopped for 300-600ms.  Commands were considered to be any
> > > > control-char or any duplicated char (likely to be cursor movement).
> > > >
> > > > Of course, latency is sometimes noticeable but that is the price
> > > > of reduced transmission data.  Most of the time, I'm typing blind
> > > > anyways -- I'm not going to focus on the screen unless needed.
> > > > Sometimes the reductions were as large as 70%, more often 50%.
> > > >
> > > > -- Robert in Houston
> > > >
> > > >
> > > > _______________________________________________
> > > > mosh-devel mailing list
> > > > mosh-devel at mit.edu
> > > > http://mailman.mit.edu/mailman/listinfo/mosh-devel
> > > >
> >