[ros-kernel] Process scheduler / timer resolution

[Witukind]

On Sat, 13 Mar 2004 03:15:42 +0100
"KJK::Hyperion" <noog at libero.it> wrote:

> At 02.15 13/03/2004, you wrote:
> by "threads" I mean "NPTL", a patch that was developed by IBM and 
> integrated officially in 2.6. I have a hard time swallowing the
> concept that clone tasks are threads

You have a point here. Fine.

> >>>PnP is not a new feature either
> >>suuure. USB hotplugging in 2.4 is a walk in the park</irony>
> >I don't see how USB hotplugging has to do with PnP
> 
> PnP is all about hotplugging - detecting new hardware immediately,
> loading the drivers and, especially, making the devices immediately
> available. Microsoft took it to an insane extreme, applying it to
> buses that don't hotplug at all, like serial and parallel ports,
> leading to "hey dude, where's my modem?" syndrome, but the Windows
> implementation is otherwise sensible

Hum no, the modem problem was because of the ISA bus. If the board had
jumpers to override the PnP and set IRQ, DMA statically it would work
fine. Windows fucks up big time when you try to put together a box with
a bunch of ISA sound blasters.

> >PnP, if my memory is correct is some "annoying feature" in some ISA 
> >extension cards.
> 
> never heard about it. I'm not even sure of what does "ISA" mean

http://www.codepedia.com/1/ISA+BUS
http://www.computerhope.com/jargon/p/pnp.htm
http://www.computerhope.com/help/bus.htm

"In 1993, Intel and  Microsoft introduced a PnP ISA bus that allowed the
computer to automatically detect and setup computer ISA peripherals such as a
modem  or sound card. Using the PnP technology an end-user would have the
capability of connecting a device and not having to configure the device using
jumpers or dipswitches."

"PnP is an ability of a computer to detect and configure a new piece of hardware
automatically, without the requirement of the user to physically configure the
hardware  device with jumpers or dipswitches."

Does that have anything to do with hotplugging? I don't remember NT4 has support
for hotplugging either...

> >But, if you wish to call everything that works when it's plugged PnP,
> >I'll go by that. Linux has had PCI support for times immemorial ;)
> 
> I think hotplugging PCI cards involves burning your power supply

It depends on which hardware. Linux has PCI hotplugging support. There was
never such a thing as "PCI PnP", because of the very nature of PCI itself.
I don't think even XP pro supports PCI hotplugging to this day hehe
So I think comments like these are clearly out of place:

"I officially welcome it in the world of real, modern operating systems"

> >>I'm not fair. I have opinions, and they aren't objective. Backed by
> >facts >yes, objective not necessarily
> >Well usually one tries to have their opinions as much acurate as
> >possible, at least I hope so.
> 
> the only accuracy in opinions is in how they reflect what one thinks
> 
> >Don't know too much about databases. But as long as the job gets
> >done, and efficiently I don't see where is the problem.
> 
> nobody sees the problem until it's solved. Linux has had a scheduler
> that ran in linear time for almost ten years, the whole time hearing
> from zealots how Linux was the bestest thing since sliced bread. Now
> that we have constant time scheduling, we realize Linux *was* the
> best... for running a basement Apache server. The point I'm trying to

still is, and did and still does a much better job than NT as a Samba server
as well.

> make is that the success of a system is completely unrelated to the
> quality of the kernel (which has sad double-edged consequences, for us
> too), and history proved this again and again. Ironically, the Windows
> NT line is a perfect example for this: a great kernel being denied any
> sort of significant innovation (most additions are patches over
> pathological issues found in previous versions, like the global cancel
> spinlock, or the inefficency of event objects as the wait object for
> critical sections) and forced to run some painfully bad user-mode
> code. I would never, ever administer a Windows server. The mess
> they've made (and keep making worse) is just too much for me to handle
> 
> >And NTFS is not so great either,
> 
> care to elaborate?

Well, for one thing, no journalling and it's slow.

> >What are you referring to when you talk of compatibility anyway?
> 
> I didn't talk of compatibility 

Well I was replying to this:
>But I think one of the worst things of Linux is the
>lack of modularity, and the lack of compatibility.