[mosh-devel] carpal tunnel, measuring latency, and how to disable prediction testing

[Frederik Eaton]

Hi Keith,

Sorry for being so slow to reply...

--predict=experimental works great. 

I did a latency experiment using the tool you linked and found that
with this option, mosh latency is a little slower than just typing in
a local shell (2.5ms vs 0.5ms) but faster than ssh on a fast
connection (25ms). Without that option, in certain circumstances it is
consistently slower than ssh (40ms): in emacs, the latency is 40ms for
the first character and 2.5ms thereafter; in zsh, if RPS1 is set then
the latency is *always* 40ms, otherwise, only for the first character
(like emacs). With "experimental", always 2.5ms everywhere... I
definitely prefer the experimental option.

My CPU might be 800MHz or 1600MHz, in fact /proc/cpuinfo shows one of
each right now.

Thanks again,

Frederick


On Wed, Jun 24, 2015 at 12:19:33AM -0700, Keith Winstein wrote:
> Frederick:
> 
> Thanks for your kind words about Mosh. For instant predictions (that might
> be wrong and get corrected by the server), please try the
> --predict=experimental option to mosh.
> 
> You can measure the latency with our term-save tool:
> https://github.com/keithw/stm-data/
> 
> Best regards,
> Keith
> 
> On Wed, Jun 24, 2015 at 12:13 AM, Frederik Eaton <frederik at ofb.net> wrote:
> 
> > Dear Mosh Developers,
> >
> > Thank you for a great product. I have thought about the need for
> > something like this for years, and was happy when I discovered 'mosh'
> > (a bit late I know).
> >
> > Your mailing list is not indexed by Google, but I downloaded the
> > archives and found there seems to be no mention of 'carpal tunnel
> > syndrome' or 'tendonitis'. I wanted to say that the reason I think a
> > product like mosh is so valuable, is that according to my own self
> > observation, typing over high-latency connections causes tendonitis. I
> > wonder that no one else has made this connection, perhaps it is my own
> > imagination. (I guess the hypothetical mechanism would be that my
> > brain sends a "work faster" signal whenever a nerve seems to be
> > working slowly, according to the delayed visual feedback, causing some
> > kind of damage to healthy nerves)
> >
> > In any case, whether for health or "minimum annoyance" reasons, I have
> > an interest in eliminating latency as much as possible. I don't care
> > if someone sees part of all of my password, or if control sequences
> > briefly show up on my editor screen. What I want is for immediate
> > visual confirmation when one of my fingers pressed a key. The man page
> > says "The predictive model must prove itself anew on each row of the
> > terminal and after each control character, so mosh avoids echoing
> > passwords or non-echoing editor commands." Is there an easy way to
> > turn this feature off in the source code? Is it a bad idea, for some
> > reason I haven't anticipated?
> >
> > My other (related) question is how to measure the actual latency. I
> > can imagine that someone may have patched xterm to log input and
> > output characters with sufficiently fine-grained timestamps, so that
> > the latency of ssh, mosh, screen, etc. could be calculated, as the
> > user presses random keys. I saw a couple things on your github issue
> > tracker which look like people are measuring these values. I'm curious
> > how to measure them myself. My initial trial of mosh (on an Arch
> > Linux, 800 MHz "Intel(R) Atom(TM) CPU N270" (32-bit)) seems to show a
> > slightly higher latency than simply typing on a local editor, and I'm
> > curious to know if this is real.
> >
> > Thank you again for your dedication and incredibly useful software
> > contribution, and also for reading my questions.
> >
> > Please Cc on replies as I'm not subscribed. Thanks,
> >
> > Frederick Eaton
> > _______________________________________________
> > mosh-devel mailing list
> > mosh-devel at mit.edu
> > http://mailman.mit.edu/mailman/listinfo/mosh-devel
> >