Re: Cygwin terminal weirdness

[Andrey Repin <anrdaemon at yandex dot ru>]

Greetings, Warren Young!

>> Call "man" on a sufficiently long topic. man bash would be quite sufficient.
>> Or just `less` a long enough text.
>> Hold down "End" key.
>> The screen buffer will jump and tear repeatedly, until you release the key.

> That sounds like a video card performance issue, not a Cygwin, mintty, or less issue.

I can't believe it is a gfx performance issue, as I can't reproduce it with
PuTTY in the same situation.
I.e.
native console/local less = jumping and tearing.
mintty/local less = jumping and tearing.
native console/ssh+less = jumping and tearing.
mintty/ssh+less = jumping and tearing.
putty+less = no jumping, no tearing.

Let's try a different approach. The video id is ne3VmLZmD9g on a well-known
tube hosting service.

> I just tried it here on a VM hosted on a box with an NVIDIA GeForce GTX
> 680MX GPU, and all I saw was normal redrawing, with scarcely any tearing. 
> That chip is about 3 years old, which probably still outperforms any current CPU-integrated GPU.

> There are some small mitigations that might help.

> One would be to convince the maintainers of less to be smarter about
> repainting the whole screen when it isnât necessary.  But given that they
> havenât fixed the horizontal scrolling bug in the ~20 years Iâve been using
> it, I wouldnât hold out hope on that front.

Well, let's say, this is unconvincing.

> Another would be to make mintty double-buffer its screen, if it doesnât
> already.  That wonât help with the clear-screen call less is currently
> making, but it might reduce the tearing effect.

> The same thing is happening with something like âls -lR /â.  The only
> difference is that you can easily see whatâs going on in the âman bashâ
> case, since the content remains static.

> Another way to see it is âvim /etc/sshd_configâ, then hold down Ctrl-L.

I'm not familiar with vi/m, so I'll just trust you on the matter.


-- 
With best regards,
Andrey Repin
Tuesday, September 15, 2015 06:47:19

Sorry for my terrible english...