uh, anybody?
-jf
On Wed, May 6, 2009 at 6:14 PM, Jeffrey 'jf' Lim <jfs.world@gmail.com> wrote:
> hey guys, I'm looking at http://linux-vserver.org/CPU_Scheduler, and
> specifically at the "Fair Share" section
> (http://linux-vserver.org/CPU_Scheduler#Fair_Share), and i'm a bit
> confused.
>
> The way the calculation works, it seems like "1/2" and "1/4" isnt
> exactly right for the wasted cpu time? It looks more like "1/2 over
> (1/2 + 1/4)" vs "1/4 over (1/2 + 1/4)" of the waste cpu time. Is this
> intentional? This is a different concept from the "standard" cpu
> scheduling, which is a "pure fraction of 1" ("hard limit").
>
> A few other questions:
>
> - the most basic one: how do i define guaranteed + fair share
> scheduling for a context? like eg. guarantee of 1/5 for a context, +
> 1/2 for fair scheduling. I'm looking at the flower page, and while I
> know what file to edit for guaranteed cpu, i dont know its format. Is
> it simply '1/5'? How about for fair scheduling? Where do i put this?
>
> - is the fair scheduling ratio "dynamic"? Let's say I have 4 contexts.
> All of them have Rk/Tk 1/4. And let's suppose that right now, 3
> contexts are idle - and only 1 context is busy. So will the wasted cpu
> time all go to this one busy context? (ie. '1/4 over 1/4'). Or is it
> more like '1/4 over (1/4 + 1/4 + 1/4 + 1/4)'?
>
> - how does this whole bucket token thing work? ie. is it a
> "sub-scheduler" within the standard kernel scheduler (kernel schedules
> vserver process, vserver process then schedules context). Or is it an
> entire "takeover/replacement" of the standard kernel scheduler?
>
> - any recommended number for "amount of tokens on start"? Let's say I
> dont want any penalization (and therefore minimum tokens = 0). And I
> want scheduling to be as smooth as possible. Then the recommended
> amount would be either 0, or fill rate? I guess this also means that i
> am asking a question about the scheduling algorithm. Does it mean that
> if a context has let's say 1000 tokens, that the scheduler will let it
> use up all its tokens (if it's that busy!) before moving on to another
> context?
>
> - any recommended number for maximum number of tokens? again, if i
> want smooth scheduling, it looks like putting the fill interval value
> here would be right.
>
> thanks,
> -jf
>
> --
> In the meantime, here is your PSA:
> "It's so hard to write a graphics driver that open-sourcing it would not help."
> -- Andrew Fear, Software Product Manager, NVIDIA Corporation
> http://kerneltrap.org/node/7228
>
Received on Fri May 8 07:21:29 2009