switching schedulers (Re: SCHED_ULE should not be the default)

[Michel Talon]

Le 16 déc. 2011 à 22:51, Doug Barton a écrit :

> On 12/16/2011 13:40, Michel Talon wrote:
>> Adrian Chadd said:
>> 
>> 
>>> Hi all,
>>> 
>>> Can someone load a kernel module dynamically at boot-time?
>>> 
>>> Ie, instead of compiling it in, can 4bsd/ule be loaded as a KLD at 
>>> boot-time, so the user can just change by rebooting?
>>> 
>>> That may be an acceptable solution for now.
>> 
>> As Luigi explained, the problem is not to have code for both
>> schedulers residing in the kernel, the problem is to migrate
>> processes from one scheduler to the other.
> 
> I think dynamically switching schedulers on a running system and loading
> one or the other at boot time are different problems, are they not?
> 


Of course, you are perfectly right., and i had misunderstood Adrian's post.
But if the problem is only to change scheduler by rebooting,
i think it is no more expensive to compile a kernel with the other scheduler. Or is it that people
never compile kernels nowadays?  The ability to switch scheduler on a running machine
would certainly be a more desirable way to test the best adaptation of the system to the load.

To come back to the problems in question about ULE i must say i don't see obvious 
malfunctions for my own use (i had some problems of this sort long ago, but they
disappeared with more recent FreeBSD).

> 
> Doug
> 
> 

--

Michel Talon
talon at lpthe.jussieu.fr