TTY task group scheduling

Andriy Gapon avg at
Fri Nov 19 09:25:34 UTC 2010

on 18/11/2010 20:56 Alexander Best said the following:
> 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.
> it might be possible that linux'es interactivity was worse than freebsd's,
> but still this patch should be evaluated for freebsd. in this particular case
> it seems linux now does better than freebsd.

You do realize that there are many more variables for such a test than just
"1080p video" and "make -j64 buildkernel"?
Let's not forget about hardware, video drivers, player capabilities, exact kind
of the video (you know, 1080p alone doesn't tell much).

Besides, someone might be interested in running -j64 on his 1,2,4-core desktop
system, but it's definitely not me.  I prefer to be reasonable.

I am not saying that our scheduler (ULE) is perfect.
I don't even say that it's better (in whatever comparison system) than Linux
scheduler X.

I say that I wouldn't spend my time improving system behavior in a scenario like
this.  I compile stuff very frequently (kernels, ports, world) while browsing
web, reading email, doing various "desktop stuff", sometimes watching  videos
from the web (like e.g. trailers).  On this machine/hardware I have never
personally felt a need for improvements in the scheduler.  And I run KDE4 with
all bells and whistles enabled.


P.S. I don't discourage anyone from improving our scheduler, I even do encourage

Andriy Gapon

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