Using symbolic execution for analyzing scheduler performance?

[Julian Elischer]

On 12/30/11 11:34 PM, arrowdodger wrote:
> On Sat, Dec 31, 2011 at 4:32 AM, Julian Elischer <julian at freebsd.org 
> <mailto:julian at freebsd.org>> wrote:
>
>     On 12/30/11 9:52 AM, arrowdodger wrote:
>
>         - OS kernel calls scheduler functions in some defined order.
>
>
>     The OS doesn't really call the scheduler in that way.
>     all sorts of threads of execution jump into the scheduler from
>     all sorts of places and
>     the internal state of the scheduler changes with these calls.
>      Sometimes those calls
>     never return, and sometimes they return a long time later..  As
>     I said, it's a very
>     complicated interface.
>
>
> Oh, threads. Yes, this imposes unimaginable complexity on what i'm 
> proposing.
>
>
>         What do you think? Does it make any sence, or i should just
>         return under my
>         rock?
>
>
>     no, come out from your rock..  If you are interested in the
>     scheduler,  by all means
>     go and read it and try and understand it, and then come back  to
>     us if you do have  ideas.
>
>
> Yeah, i think it's what i should've done in first place, before 
> dumping by brain to ML.
> Okay, i will try to get an idea of how schedulers work in detail and 
> after that will try to find parts of it, which can be automatically 
> verified.
>
> BTW, is there any documentation on how write schedulers for FreeBSD, 
> or at least, ULE specification?

there is a paper that was presented somewhere on ULE,
but the best source of information is of course the code..
start by reading the 4bsd scheduler.. as it's simpler..

>
>     I don't think your idea is really bad but I think you
>     underestimate the difficulty of the task.
>
>         PS: Sorry for my english, i hope you understood what i've
>         been trying to
>         say.
>
>     your english is fine.. what do you normally speak?
>
>
> Russian.

there are a lot of russian developers so you should be able to find 
someone if you need explanations in Russian..

>
>     (and you are not really 6 years old, are you? :-)
>
>
> Yeah, i've grown up a little, since then.
>
> Thanks for your insight!