Re: [MiNT] Issue with Mint 1.19 and Litchi (maybe solved)

[Lonny Pursell <atari@bright.net>]

on 2/6/15, 5:32 AM, Vincent Rivière wrote:

> On 06/02/2015 03:32, Pierre Ton-That wrote:
>> Well, guess what? Fselect(1,...) is used by my internet programs, to
>> wait for the second and next datas. So receiving functions are
>> prematuraly exited.
> 
> Aha :-)
> 
> Regarding to this issue, I have 2 feelings.
> 
> 1) Multitasking programs should not wait for extremely small delays such
> as 1ms. This suggests a very fast infinite loop in the main program,
> which would lead to things like 100% CPU usage when not necessary.
> Usually, this is a symptom of bad design, but of course there can be
> exceptions.
> 
> Normally, multitasking programs should:
> - Either wait for a long delay for something to happen (a few seconds).
> So the kernel can give the CPU to other tasks.
> - Either ask for a status and don't wait at all, carefully avoiding
> infinite loops which could result in 100% CPU.
> 
> 2) In the Fselect() API, 0 means infinite delay. There was no way to ask
> it to return immediately with no delay. On the opposite, in the select()
> UNIX call, 0 means no delay, and that's what programs such as vim expect.
> 
> Alan introduced a new behaviour in Fselect() to fix the slowness of old
> binaries:
> - 0: infinite delay (as usual)
> - 1: NEW: no delay
> - 2 and higher: normal delay
> 
> We assumed that it was safe, because no programs were supposed to
> deliberately call Fselect(1,...). But we were wrong, that change broke
> MyAES and Pierre's software.
> 
> Anyway:
> In recent MiNTLib, the select() UNIX function has be implemented using
> Fpoll() instead Fselect(), so recently recompiled programs such as vim
> have no problem with the old Fselect() implementation. The Fpoll() API
> supports no-delay.
> 
> Finally, I think we should consider to revert the Fselect() change in
> FreeMiNT, since it broke old software, and it is no more useful for new
> binaries...

I have found also Fselect(1,...) in my VNC client.


-- 
Lonny Pursell    http://www.bright.net/~gfabasic/