Re: [gtk-list] Re: X and idles => incredible slowdowns

[Antonio Campos <acampos extremadura com>]

Paul Barton-Davis wrote:

> >I have tried the enclosed program over Windows 95 (with the GTK Win32
> >port), and Windows behaves very well indeed. No noticeable slow downs
> >here.
>
> AFAIK, Windows 95 uses cooperative multitasking, not preemptive
> multitasking, and the various components of the system that you use
>

Sure?. I'm not so sure about that... I've not tried my test program on WNT,
W2000 (those are true preemptive, aren't they?), but I think the same result
would be obtained, I mean, better responses to user interactions that Linux+X.

> when you are running a GTK Win32 application are written to allow each
> other to take control of the machine at the "right" times.
>
> Linux uses preemptive multitasking, and as Havoc pointed out, 3
> applications competing, rather than cooperating, for 100% of the CPU
> will not work in such a system.
>

But you have to agree with me, that an application being able to take almost
all the control of the X server, IS A VERY BAD THING. It makes posible
malicious applications, X hangs and therefore Linux hangs, etc.

I changed the scheduling policy of the X server process to SCHED_RR or
SCHED_FIFO and everything worked more smoothly. My application wasn't able to
take the control of the X server. I could move my mouse smoothly over the
screen, and the rest of the applications responded to my actions. But problems
arised, like XMMS not being able to play the music smoothly when I opaquely
moved big windows around the screen.

I think this is a serious inconvenience of the X system that should be
corrected by the XFree Team (or at least the XFree Team should know this
issue), because it makes Linux and easy-to-crash system.
I also don't understand that a single client process can send requests to the
server, but the others clients can't mix its requests between the requests of
the others. I don't understand why the server only cares about the process
that most request it.

Anybody knows a mailing-list or a newsgroup where one can complaint the Xfree
team about things like this?

>
> >However, if this is a X/XFree problem, could anybody tell the XFree team
> >about it? (It's a pity that the Xfree team doesn't have a mailing list
> >to talk about these things, or am I wrong?)
>
> It has nothing to do with XFree, and everything to do with the fact
> that Linux and Windows are completely different kinds of operating
> systems. To see why the Windows one can lead to problems (since this
> example shows it in a somewhat glowing light), consider what would
> happen on Windows if an application refused to cooperatively
> multitask ... on Linux, this cannot happen unless you are root and the
> program requests real-time scheduling.
>
> --p
>
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