Re: [PATCH] mm: yield during swap prefetching

[Con Kolivas <kernel@kolivas.org>]

Zan Lynx writes:

> On Wed, 2006-03-08 at 14:05 +1100, Con Kolivas wrote:
> > André Goddard Rosa writes:
> >
> > > [...]
> > >> > > Because being a serious desktop operating system that we are
> > >> > > (bwahahahaha) means the user should not have special privileges to run
> > >> > > something as simple as a game. Games should not need special scheduling
> > >> > > classes. We can always use 'nice' for a compile though. Real time audio
> > >> > > is a completely different world to this.
> > > [...]
> > >> Well as I said in my previous reply, games should _not_ need special
> > >> scheduling classes. They are not written in a real time smart way and they do
> > >> not have any realtime constraints or requirements.
> > >
> > > Sorry Con, but I have to disagree with you on this.
> > >
> > > Games are very complex software, involving heavy use of hardware resources
> > > and they also have a lot of time constraints. So, I think they should
> > > use RT priorities
> > > if it is necessary to get the resources needed in time.
> >
> > Excellent, I've opened the can of worms.
> >
> > Yes, games are a in incredibly complex beast.
> >
> > No they shouldn't need real time scheduling to work well if they are coded
> > properly. However, witness the fact that most of our games are windows
> > ports, therefore being lower quality than the original. Witness also the
> > fact that at last with dual core support, lots and lots (but not all) of
> > windows games on _windows_ are having scheduling trouble and jerky playback,
> > forcing them to crappily force binding to one cpu.
> [snip]
>
> Games where you notice frame-rate chop because the *disk system* is
> using too much CPU are perfect examples of applications that should be
> using real-time.
>
> Multiple CPU cores and multithreading in games is another perfect
> example of programming that *needs* predictable real-time thread
> priorities.  There is no other way to guarantee that physics processing
> takes priority over graphics updates or AI, once each task becomes
> separated from a monolithic main loop and spread over several CPU cores.
>
> Because games often *are* badly written, a user-friendly Linux gaming
> system does need a high-priority real-time task watching for a special
> keystroke, like C-A-Del for example, so that it can kill the other
> real-time tasks and return to the UI shell.
>
> Games and real-time go together like they were made for each other.

I guess every single well working windows game since the dawn of time is
some sort of anomaly then.

Cheers,
Con

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