Re: TTY task group scheduling

On Fri Nov 19 10, Daniel Nebdal wrote:
> On Fri, Nov 19, 2010 at 12:06 AM, Alexander Kabaev <kabaev_at_gmail.com> wrote:
> > On Thu, 18 Nov 2010 18:56:35 +0000
> > Alexander Best <arundel_at_freebsd.org> wrote:
> >
> >> On Thu Nov 18 10, Matthew D. Fuller wrote:
> >> > On Thu, Nov 18, 2010 at 06:23:24PM +0000 I heard the voice of
> >> > Alexander Best, and lo! it spake thus:
> >> > >
> >> > > judging from the videos the changes are having a huge impact imo.
> >> >
> >> > Well, my (admittedly limited, and certainly anecdotal) experience is
> >> > that Linux's interactive response when under heavy load was always
> >> > much worse than FreeBSD's.  So maybe that's just them catching up to
> >> > where we already are   ;)
> >>
> >> well...i tried playing back a 1080p vide files while doing
> >> `make -j64 buildkernel` and FreeBSD's interactivity seems far from
> >> perfect.
> >
> > One thing that just begs to be asked: since when decoding 1080p became
> > an interactive task?
> >
> 
> Strictly speaking it isn't - but displaying it is a timing-sensitive
> task that isn't CPU- or I/O-bound, and scheduling-wise that probably
> makes it more like the "fast response when woken up" interactive tasks
> than a CPU-bound non-interactive process.
> Decoding it into another file on the disk is in the latter category,
> of course - but I don't think that's what he meant. :)
> 
> More on topic - while this was a tiny patch for Linux, it seems like
> it would take more work for us, since I don't believe either of the
> schedulers handles task groups in the required way. The linux patch
> was just "create task groups automatically", since they already had
> some suitable logic for scheduling based on task groups in their CFS
> scheduler. We would have to (re-)add that first, which is non-trivial.

personally i think freebsd would hugely benefit from a scheduler framework
such as geom/gsched, where it's easy to switch between various algorithms.

that way it be much easier to try out new concepts without having to write a
completely new scheduler.

cheers.
alex

> 
> 
> --
> Daniel Nebdal

-- 
a13x